UNIVERSITY  OP  CALIFORNIA 

SCHOOL  OF  PUBLIC  HEALT^ 

35a3  LIFt  SOENCCS  8UlLOIN( 


HYGIENE    AND    PUBLIC    HEALTH 


HYGIENE 


AND 


PUBLIC   HEALTH 


LOUIS  C.  PARKES,  M.D.,  D.P.H.  Univ.  of  Lond. 

CONSULTING  SANITARY  ADVISER  TO  H.M.  OFFICE  OF  WORKS;  LATE  CIVILIAN  SANITARY  MEMBEK 

OF   THE   ADVISORY    BOARD    FOR    ARMY    MEDICAL    SERVICES  ;    MEDICAL   OFFICER   OF 

HEALTH    OF   THE    METROPOLITAN    BOROUGH   OF    CHELSEA  ;    EXAMINER 

IN    PUBLIC   HEALTH   TO  THE   ROYAL  COLLEGES   OF   PHYSICIANS 

AND   SURGEONS,    LONDON  ;    FELLOW    OF   THE   ROYAL 

SANITARY    INSTITUTE 

AND 

HENRY  R.  KENWOOD,  M.B.,  F.R.S.  Edin. 
D.P.H.  Lond. 

CHADWIC^  PROFESSOR  OF  HYGIENE  IN  THE  UNIVERSITY  OF  LONDON  ;    MEDICAL  OFFICER  OF 

HEALTH    AND   PUBLIC   ANALYST    OF   THE    METROPOLITAN     BOROUGH   OF    STOKE 

NF.WIMGTON  AND  MEDICAL  OFFICER  OF  HEALTH    FOR  THE    COUNTY 

OF     BEDFORDSHIRE  ;     EXAMINER    IN    PUBLIC   HEALTH   TO 

THE     ROYAL     COLLEGES     OF      PHYSICIANS     AND 

SURGEONS,  LONDON  ;      FELLOW    OF 

THE      ROVAL      SANITARY 

INSTITUTE 


FIFTH   EDITION,  WITH   ILLUSTRATIONS 


PHILADELPHIA 

BLAKISTON'S    SON    &    CO. 

IOI2    WALNUT    STREET 
I913 


Printed  in  England 


Public  Health  Li"b 


/?/  3 

PUBLIC 
HEALTH 
UBHAftY 


PREFACE 

This,  the  fifth  edition  under  the  conjoint  authorship  of  a 
vv^ork  which  had  previously  run  through  five  editions,  has  been 
carefully  revised,  and  new  matter  has  been  introduced,  where 
necessary,  to  bring  the  work  up  to  date  since  the  last  edition 
was  issued  in  1911.  The  authors  desire  to  acknowledge  their 
indebtedness  to  Dr.  Elizabeth  Eraser's  Manual  of  Immunity  for 
the  article  on  this  subject  in  Chapter  IX. 

L.  C.  P. 

H.  R.  K. 

September.   191 3 


CONTENTS 


CHAPTEK 

I.  Water    ........... 

II.  The  Collection,  Remov.\l,  and  Disposal  of  Excretal  and 
OTHER  Refuse    . 

III.  Air  and  Ventilation    . 

IV.  Warming  and  Lighting 
V.  Soils  and  Building  Sites 

VI.  Climate  and  Meteorology 
VII.  Exercise  and  Clothing 
VIII.  Food,   Beverages,   and  Condiments 

IX.  The  Contagia — Communicable  Diseases  and  their 

VENTION — Hospitals  . 

X.  School  Hygiene    .... 
XT.  Disinfection  .... 

XII.  Statistics        ..... 
XIII.  Sanitary  Law  and  Administration 

Inde.x  ...... 


Pre 


PAGE 
I 


72 
167 

263 
276 
303 
313 

408 

558 
598 

631 
663 

728 


LIST   OF    ILLUSTRATIONS 


r .  Underground  Water  Curves  ...... 

2.  Depression  of  Water  in  Shallow  Well  by  Pumping 

3.  Diagrammatic  Section  through  London  Basin 

4.  Diagrammatic    Representation    of    Strata,    showing    Shallow 

Deep,  and  Artesian  Wells     . 

5.  Suction  Pump    .         .         .  .  .         . 

6.  Single-acting  Suction  and  Force  Pump 

7.  Double-acting  Suction  and  Force  Pump     . 

8.  Centrifugal  Pump       ..... 

9.  Hydraulic  Ram  ..... 

10.  Mercurial  Vapour  Lamp  for  Sterilizing  Water 

1 1 .  Berkefeld  Filter  ..... 

12.  Cesspool  with  House  Drain  Inlet  and  Overflow  to  Filter  Bed 

13.  Privy  constructed  for  Pail  System 

14.  Field's  Annular  Siphon  Flush  Tank  for  Flushing  House  Drains 

15.  Long  Hopper  Water-closet  with  Side-inlet  for  Flushing 

16.  Wash-down  Water-closet 

17.  Wash-out  Water-closet 

1 8.  Century  Siphonic  Closet 

19.  Era  Valve  Closet 

20.  S-trap,  with  Water-seal 

21.  P-trap,  with  Water-seal 

22.  Trough  Water-closet 
2  7,.  New  Form  of  Trough  Closet  or 

24.  Day's  Waste-water  Closet 

25.  Wiped  Soldered  Joint 

26.  Joint  made  with  Copper  Bit  or  Blow- pipe 

27.  Soil  Pipe  and  Ventilator,  with  Anti-siphonage  Pipes  from  the 

Water-closet  Branches  .... 

28.  Section  of  Disconnecting  Chamber 

29.  Flushing  Grease  Gulley      ..... 

30.  Semi-detached  Houses,  Old  and  Modern  Drainage 

31.  Dean's  Silt  Gulley      ...... 

^2.  Diagrammatic  Sketch  of  Various  Provisions  for  Ventilation 

^7,.  Sturtevant  Pneumatic  Dust-collecting  System  . 


Latrine  with  Isolated  Pans 


PAGE 

22 

25 
29 

32 
35 
35 
35 
35 
36 
56 
63 
79 
81 
86 
89 
89 
89 
91 
93 
95 
95 
96 

97 
98 

lOI 
lOI 

103 
108 
113 
114 
119 
222 
233 


LIST    OF    ILLUSTRATIONS 


34.  Plenum  System  ..... 

35.  Rifle-back  Stove  with  Economizer 

36.  Euthermic  Ventilating  Gas  Stove 

37.  Types  of  Radiators  with  Fresh-Air  Inlets 

38.  House  Foundation  with  Damp-proof    Course  in  Wall  and  Dry 

Area     ....... 

39.  Synoptic  Chart  showing  Cyclonic  System 

40.  Synoptic  Chart  showing  Anticyclonic  System 

41.  Fortin's  Standard  Barometer 

42.  Diagram  of  Barometer  Scale  and  Vernier 

43.  Robinson's  Anemometer    . 

44.  Daniell's  Hygrometer 

45.  Regnault's  Hygrometer 

46.  Wet  and  Dry  Bulb  Hygrometer 

47.  Rain  Gauge        .... 

48.  Six's  Thermometer     . 

49.  Solar  Radiation  Thermometer 

50.  Sunshine  Recorder 

5 1 .  Cotton  Fibres 

52.  Linen  Fibres 

53.  Wool  Fibres 

54.  Silk  Fibres 

55.  Hemp  Fibres 

56.  "  Measly  "  Pork,  showing  (diagrammatically)  its  Appearance  to 

the  Naked  Eye    . 

57.  Head  of  Taenia  solium 

58.  Head  of  Taenia  mediocanellata  . 

59.  Brood  Capsule  of  an  Echinococcus 

60.  Trichina  spiralis  encj'sted  in  Muscle 
6j.  One  of  Rainey's  Capsules 

62.  Distoma  hepaticum    . 

63.  Percentage  Composition  of  Solids  of  Human  and  Cow's  Milk 

64.  Aspergillus  Glaucus    . 

65.  Penicillium  Glaucum 

66.  Mucor  Mucedo  . 

67.  Puccinia  Graminis 

68.  Smut  Spores:  Uredo  segetum 

69.  Acarus  farinae     . 

70.  Vibriones  tritici 

7 1 .  Weevil        .... 

72.  Section  ol  Wheat  Grain:  Outer  Coat 

73.  A,  Ear  of  Rye  with  Ergot;  B,  a  Slice  of  Ergot 

Plates  I.  and  II.     Illustrating  Starch  Grains  .  facing 

74.  Coffee:  Cells  of  Testa  and  Cellular  Structure 

75.  Chicory:   Dotted  Ducts  and  Cellular  Structure 


234 
244 
248 
251 

270 
28s 
286 
289 
289 
291 
292 

293 

294 
296 
299 
300 
301 
306 

307 
308 

309 
310 

233 
333 
334 
334 
33  5 
336 
338 
357 
366 
366 
368 
383 
383 
383 
384 
384 
384 
384 
386 
388 
388 


LIST    OF    ILLUSTRATIONS  xi 

Fit;.  I'AfiE 

76.     Tea  Leaf    ...........     389 

"/■J.     Torula  cerevisias:  Yeast  Plant   .  .         .         .         .         .         .391 

78.  Fulham  Small-pox  Hospital.     Special  Area  divided  into  Sec- 

tions, showing  Number  of  Houses  invaded  by  Small-pox   .     430 

79.  Chart   showing    Average    Death-rates    in    different    Infectious 

Diseases  in  Corresponding  Weeks  of  a  Period  of  Years      .     433 

80.  Small-pox  Epidemics,  1S71,  1881  ;  Mortality  per  cent,  in  Fever 

Hospitals  (London)       ........  437 

81.  Musca  domestica  (after  Hewitt)         ......  479 

82.  Diagrammatic  Section  of  a  Fly          ......  479 

83.  Leg  and  Foot  of  a  Fly      ........  479 

84.  Fly  extruding  Bubble  from  Crop       ......  479 

85.  Hospital  Slop-sink  with  Flushing  Rim  and  Bed-pan  and  Slipper 

Douches       .         .         .         .         .         .  .         .         .         -552 

86.  Borough  Hospital,  Croydon.     First-lioor  Plan  .         .         .         -555 

87.  Isolation  Hospital  Block  (as  recommended  by  the  Local  Govern- 

ment Board)         .         .         .         .         .         .         .         .         -555 

88.  Diagrammatic  Representation  of  E-shaped  School   .         .         -558 

89.  The  Staffordshire  Type  of  Elementary  School  .         .         .         -559 

90.  (a)  Disinfecting  Station.     Infected  Side     .....     608 
(fe)  Disinfecting  Station.     Non-infected  Side      ....     609 

9 1 .  Graphic  Expression   of    ■Male   Population :   Number  Living  or 

Lives  at  Risk       .........     654 

92.  A    Sanitary    Cowshed.      Double    Byre    with   Central    Feeding 

Passage        ......  ...     690 


HYGIENE  AND  PUBLIC  HEALTH 


CHAPTER  I 
WATER 

Water  is  a  prime  necessity  of  life.  Without  it,  terrestrial 
animal  and  vegetable  life  must  cease  to  exist.  The  earliest 
settlements  in  all  countries  were,  therefore,  made  in  the  neigh- 
bourhood of  water.  Towns  and  villages  sprang  up  on  the  banks 
of  streams  and  rivers,  on  the  shores  of  lakes  and  in  the  neigh- 
bourhood of  springs ;  or  water  was  obtained  from  the  soil  around 
these  early  settlements  by  shallow  excavations  or  wells.  In 
modern  times,  sites  for  dwelhngs  are  not  necessarily  limited  to 
a  small  area  around  a  natural  source  of  water.  Our  engineering 
knowledge  enables  us,  on  the  one  hand,  to  obtain  water  by 
means  of  wells  and  borings  from  great  depths  beneath  the  surface 
of  the  earth,  and  on  the  other,  to  convey  water  from  a  distance 
by  means  of  conduits  to  the  places  where  it  is  required. 

This  latter  method  was  well  known  to  the  ancient  Romans, 
many  of  whose  aqueducts  and  reservoirs  are,  after  the  lapse  of 
many  centuries,  still  standing  and  serving  their  original  pur- 
pose. In  Rome  the  total  supply  per  head  was  certainly  not 
less  than  300  gallons  daily  for  a  population  of  about  1,000,000 
people,  the  greater  portion  of  this  vast  supply  of  water  being 
required  for  public  baths  and  fountains. 

London  is  an  instance  of  a  settlement  founded  originally  on 
the  banks  of  a  river,  and  subsequently  spreading  away  from 
the  neighbourhood  of  the  river  only  in  those  directions  where 
a  water-bearing  gravel  overlaid  the  impermeable  London  clay. 
The  bed  of  gravel  being  of  but  sHght  thickness — 10  to  30  feet^ 
water  was  easily  reached  by  shallow  excavations  or  wells; 
whilst   at   some  places  springs  flowed  out  where  the  gravel 


2  HYGIENE    AND   PUBLIC   HEALTH 

terminated,  as  at  Bagnigge,  Holj^vell,  and  Clerkenwell.  Eighty 
years  ago,  parts  of  London  where  the  clay  came  to  the  surface, 
and  which  are  now  densely  populated  owing  to  the  introduction 
of  a  public  water  supply,  were  quite  uninhabited. 

Sources  of  Water — Collection  and  Storage. 

The  natural  sources  of  water  are  the  rain  and  snow  which 
fall  on  the  surface  of  the  earth.  When  the  rain  has  reached 
the  surface  of  the  ground,  it  is  disposed  of  in  the  following  wa3's : 
a  portion  (a)  is  evaporated;  another  portion  (b)  flows  off  in 
the  direction  of  the  inclination  of  the  surface;  whilst  a  third 
portion  (c)  sinks  into  or  percolates  through  the  interstices  of 
the  soil. 

The  amount  of  rain  that  evaporates  depends  upon  the  tem- 
perature of  the  air.  The  higher  the  temperature,  the  greater 
the  evaporation.  If  the  inclination  of  the  surface  is  nil,  or 
only  very  slight,  and  the  soil  is  of  some  depth  and  of  a  porous 
nature,  the  larger  portion  sinks  into  the  soil  or  percolates.  If, 
however,  the  inchnation  of  the  surface  is  great  and  the  soil  is 
not  porous,  but  more  or  less  impermeable  to  water,  the  greater 
portion  of  the  imevaporated  rain  flows  down  the  incline.  It  is 
this  portion  which  forms  or  helps  to  swell  the  brooks,  streams, 
and  rivers,  which  are  the  natural  drainage  channels  of  the  locahty. 
In  very  porous  soils,  such  as  pure  sand  or  coarse  gravel,  the 
rain  so  rapidly  sinks  into  the  interstices  of  the  soil  that  the 
evaporation,  even  in  summer,  is  but  shght.  In  nearly  all  other 
soils,  however,  the  amount  of  rain  evaporated  greatly  exceeds 
the  percolation,  even  in  winter. 

The  portion  that  percolates,  after  a  certain  deduction  that 
must  be  made  for  the  moisture  absorbed  by  the  roots  of  vege- 
tables and  grasses  growing  on  the  surface,  and  which  is  subse- 
quently evaporated  from  their  leaves,  helps  to  form  and  renew 
the  underground  sources  of  water.  These  are  made  available 
to  man  by  natural  outlets  as  springs,  or  by  artificial  tappings 
in  their  subterranean  depths  through  wells. 

In  its  passage  through  the  soil,  the  water  absorbs  carbonic 
acid  from  the  ground  air,  which  is  very  much  richer  in  this  gas 
than  ordinary  atmospheric  air.  This  water  holding  carbonic 
acid  gas  in  solution  is  capable  of  dissolving  some  of  the  mineral 
constituents  of  the  rocks  through  which  it  passes. 


WATER  3 

Rainfall. 

The  rain  that  falls  on  the  roofs  of  houses  can  be  collected  and 
made  available  as  a  means  of  water  supply.  To  calculate  the 
amount  of  water  supply  per  head  from  this  source,  we  must 
know  the  amount  of  roof  space  per  individual  (the  slope  of 
the  roof  must  not  be  taken  into  account,  but  merely  the  area 
of  horizontal  surface  covered  by  the  roof),  the  average  amount 
of  yearly  rainfall,  and  the  average  amount  of  evaporation  of 
the  rainfall. 

The  amount  of  yearly  rainfall  varies  considerably  in  different 
parts  of  England.  In  the  Eastern  Counties  the  average  is  less  than 
25  inches  per  annum.  Throughout  the  remainder  of  England 
the  average  is  from  30  to  40  inches  per  annum,  with  very  much 
larger  amounts  in  the  mountainous  and  hilly  districts  of  Devon- 
shire, Wales,  Cumberland  and  Westmorland  (60  to  200  inches  per 
annum).  The  expression  "  an  inch  of  rainfall  "  signifies  that 
one  cubic  inch  of  rain-water  has  fallen  upon  each  square  inch  of 
horizontal  surface.      (For  description  of  rain  gauge  see  Chap.  \  I.) 

During  the  past  15  years  the  least  annual  rainfall, 
measured  at  Greenwich,  has  been  18-85  inches  (1898),  and  the 
greatest  35 '54  inches  (1903).  In  the  latter  year  (1903)  ex- 
ceptionally heavy  falls  of  rain  occurred;  thus  on  July  23,  247 
inches  fell  in  24  hours,  and  on  numerous  occasions  over  an  inch 
fell  in  the  same  period.  During  the  13  years  1890-1902,  the 
annual  rainfall  at  Greenwich  had  been  below  the  average 
(24-53  inches)  in  11  years,  and  only  twice  slightly  exceeded  the 
average,  namely  in  1891  and  in  1894. 

Rain  is  also  sometimes  collected  from  prepared  surfaces  of 
ground,  which,  together  with  the  storage  reservoir  or  tank, 
should  always  be  railed  off  to  keep  Hve  stock  away.  The  surface 
of  a  certain  area  of  land  in  an  exposed  situation  is  rendered 
impermeable  by  a  covering  of  slates,  asphalt,  or  cement,  and 
sloped  towards  an  outlet  pipe  or  pipes  leading  to  a  tank  or 
reservoir.  In  estimating  the  amount  of  water  that  can  be 
obtained  from  such  a  surface  calculations  may  be  facilitated 
by  remembering  that  one  inch  of  rain  delivers  4-673  gallons  on 
every  square  yard,  or  22,617  gallons  (loi  tons)  on  each  acre. 

The  amount  of  evaporation  from  the  surfaces  of  roofs  may  be 
taken  as  averaging  throughout  the  year  20  per  cent,  of  the 
rainfall.     There  is  more  evaporation  from  tiled  than  from  slated 


4  HYGIENE   AND   PUBLIC  HEALTH 

roofs,  and  from  roofs  of  low  than  of  steep  pitch.  The  evapora- 
tion is  greatest  where  the  rainfall  is  least,  and  vice  versa.  If 
the  amount  of  roof  space  per  head  is  60  square  feet,  and  the 
rainfall  30  inches  in  the  year,  deducting  one-fifth  for  evaporation, 
120  cubic  feet  or  748  gallons  is  the  amount  available  for  each 
person  in  a  year,  which  is  equal  to  about  two  gallons  daily. 
This  is  the  amount  available  from  the  rainfall — 30  inches — of 
an  average  year.  It  has  been  found  from  a  great  number  of 
records  of  rainfall  extending  over  a  long  series  of  years  in  different 
places,  that  the  rainfall  in  the  driest  year  is  usually  one-third 
less  than  the  average  fall,  whilst  in  the  wettest  year  it  is  one- 
third  greater  than  the  average.  So  that  in  a  very  dry  year  in 
the  example  given  above,  the  amount  of  water  available  may  be 
only  I J  gallons  daily  per  head,  whilst  in  a  very  wet  year  it  may 
be  2§  gallons. 

Rain,  as  it  leaves  the  clouds,  is  water  pure  and  simple,  free 
from  all  foreign  ingredients.  In  its  passage  through  the  air  to  the 
earth  it  may  collect  various  impurities,  gaseous  and  suspended. 
The  rain  falling  in  towns  is  found  to  have  absorbed  sulphurous 
and  sulphuric  acids,  which  are  always  present  in  the  air  of 
towns  from  combustion  of  coal  and  coal  gas,  and  to  contain 
numerous  sooty  particles. 

It  also  appears  that  the  rain  washes  out  of  the  air  countless 
bacterial  and  fungoid  organisms  and  their  spores.  The  rain 
which  first  falls  after  a  period  of  dry  weather  contains  far  larger 
numbers  of  bacteria  than  that  which  falls  later  in  a  storm; 
200,000  germs  per  Htre  is  not  an  unusual  quantity  under  such 
circumstances.  During  the  warm  months  of  the  year,  the  number 
of  bacteria  in  the  rain  exceed  those  found  in  the  rain  of  winter 
and  early  spring.  The  greater  number  of  the  organisms  in  rain 
are  micrococci.  Besides  bacteria,  pollen  of  grasses  and  flowers, 
microscopic  plants,  such  as  Protococcus  phtvialis  and  spores  of 
fungi,  are  occasionally  found  in  rain,  the  latter  being  on  rare 
occasions  in  sufficient  quantity  to  cause  a  locaUzed  fall  of  what 
is  known  as  "coloured  rain";  but  dust,  possibly  of  volcanic 
origin,  or  derived  from  vast  sand  deserts,  is  sometimes  responsible 
for  falls  of  coloured  rain. 

Rain  is  thus  seen  to  be  a  great  purifier  of  air,  for  it  washes 
out  of  it  gaseous  and  solid  impurities,  organic  and  inorganic. 
For  this  reason  the  rain  which  falls  in  the  impure  smoke  and 
soot-iaden  atmosphere  of  large  towns  is  unfit  to  drink. 


WATER  5 

When  roofs  are  used  as  collecting  surfaces  for  rain-water, 
the  first  portion  of  rain  which  falls  and  descends  from  the  roof 
should  be  rejected,  as  it  is  hable  to  be  much  polluted  with  soot, 
vegetable  matter  (leaves),  and  animal  matter  (excrement  of 
birds,  etc.)  washed  off  from  the  slates  or  tiles.  After  the  first 
washing  the  remainder  of  the  water  may  be  collected  and  stored. 
Robert's  Rain-water  Separator,  which  can  be  fixed  on  the 
downward  course  of  the  rain-water  pipe,  effects  this  purpose 
by  allowing  the  first  portion  of  water  that  passes  through  the 
apparatus  to  run  to  waste.  After  a  certain  time,  a  part  of  the 
apparatus  which  is  balanced  on  a  pivot  cants  over,  owing  to 
its  centre  of  gravity  being  altered  as  one  of  its  compartments 
fills  with  water,  and  the  water  escapes  into  another  pipe,  which 
conducts  it  to  a  storage  cistern.  Rain-water  should  always  be 
stored  in  as  pure  a  condition  as  possible,  otherwise  the  storage 
receptacle  becomes  coated  with  foul  matters,  which  contaminate 
the  water.  The  advantage  of  underground  storage  is  that  the 
water  does  not  get  frozen  in  the  winter  or  unpleasantly  hot  in 
the  summer.  But,  on  the  other  hand,  the  tanks  are  often 
difficult  of  access.  Underground  tanks  must  be  built  of  sound 
masonry  or  brickwork  and  lined  with  hydraulic  cement.  They 
should  rest  upon  a  bed  of  concrete  and  be  covered  over  with 
arches  of  masonry  or  brickwork;  and  if  there  is  a  special  danger 
of  polluting  material  gaining  access  to  the  tank,  they  should 
be  surrounded  with  at  least  a  foot  of  well-puddled  clay. 

Rain-water  is  especially  useful  for  cooking  and  washing  on 
account  of  its  softness — that  is  to  say,  its  freedom  from  the 
salts  of  lime  or  magnesia  in  solution.  When  these  salts  are 
dissolved  in  a  water  they  render  it  hard.  Hardness  is  usually 
reckoned  as  equivalent  to  so  many  grains  of  chalk  (or  carbonate 
of  calcium)  per  gallon  of  water.  A  water  containing  more  than 
10  grains  of  chalk  or  its  equivalent  in  other  salts  (sulphate  of 
lime  or  magnesia,  carbonate  of  magnesia,  etc.)  to  the  gallon 
is  said  to  be  hard.  Hardness  due  to  the  presence  of  carbonate 
of  calcium,  held  in  solution  by  carbonic  acid,  is  said  to  be 
temporary ;  for  when  the  water  boils,  the  carbonic  acid  is 
driven  off,  and  the  chalk,  no  longer  able  to  remain  in  solution, 
is  precipitated. 

It  is  this  deposit  of  chalk  which  causes  the  fur  on  the  bottom 
and  sides  of  boilers  and  kettles.  When  meat  or  vegetables  are 
cooked  by  boiling  in  hard  water,  a  certain  amount  of  the  hard 


b  HYGIENE   AND    PUBLIC   HEALTH 

material  is  deposited  on  their  surfaces,  which  either  hinders  the 
proper  penetration  of  the  heat  into  the  interior,  or  prevents 
solution  of  the  soluble  materials  when  this  is  desired.  The  fur 
lining  is  also  a  non-conducting  material,  and  impedes  the  passage 
of  heat  from  the  fire  to  the  contents  of  the  boiler  or  kettle,  thus 
causing  a  waste  of  fuel.  This  fur  lining  is  one  of  the  causes  of 
the  boiler  explosions  from  which  loss  of  life  not  infrequently 
results.  To  reduce  the  possibility  of  such  explosions  the  follow- 
ing precautions  are  desirable :  — The  boilers  should  be  of  wrought 
iron,  properly  tested;  they  should  be  periodically  inspected  and 
cleaned;  pipes  connected  with  them  should  not  be  carried  up 
external  walls  where  they  may  be  affected  by  frost,  and  the 
cisterns  should  also  be  in  well-protected  positions;  the  safety 
valve  should  be  accessible,  easily  adjusted,  and  sensitive  to 
variations  of  pressure. 

Great  waste  of  soap,  too,  is  caused  by  the  use  of  hard  water 
in  washing.  When  the  water  is  hard,  the  lime  or  magnesia 
combines  with  the  fatty  acid  of  the  soap,  forming  a  curdy  pre- 
cipitate; and  all  the  lime  or  magnesia  of  the  water  must  be  so 
combined  before  a  lather  can  be  formed.  Consequently  a  certain 
amount  of  soap  is  wasted.  One  grain  of  chalk  wastes  about 
eight  grains  of  soap. 

The  hardness  of  rain-water  is  generally  less  than  half  a  degree ; 
that  is  to  say,  there  is  less  than  half  a  grain  of  chalk  or  its  equiva- 
lent salts  to  the  gallon  of  water;  hence  its  value  for  domestic 
purposes.  Rain-water  should  never  be  allowed  to  run  to  waste 
where  the  water  derived  from  other  sources  is  hard.  There  is 
one  great  disadvantage  possessed  by  rain  and  other  soft  waters, 
namely,  their  liabihty  to  dissolve  lead,  iron,  or  zinc  if  left  in 
contact  with  these  metals.  Consequently  cisterns  of  lead,  iron, 
zinc  and  even  galvanized  iron  in  some  cases  should  not  be  used 
to  store  soft  water;  and  such  water  when  collected  from  lead 
roofs  should  not  be  used  for  drinking. 

Upland  Surface  Waters. 

In  hilly  districts,  the  water  which  flows  off  the  hills  in  the 
form  of  rivulets  or  streamlets  can  be  collected  and  stored  by 
building  an  earth  and  masonry  dam  or  barrier  across  the  outlet 
of  the  valley  to  which  the  streams  converge.  By  this  method 
of  collecting  in  "  impounding  reservoirs,"  large  artificial  lakes 
may   be    formed — ca})able   of    holding    a   supply   sufficient    for 


WATER  7 

several  months — at  suitable  elevations  above  the  towns  which 
they  supply  with  water.  A  certain  amount  of  "  compensation  " 
water  (usually  estimated  at  one-third  the  amount  impounded) 
must  be  allowed  to  pass  down  to  any  mill-owners  on  the  streams 
from  which  the  waters  have  been  diverted. 

Large  storage  reservoirs  for  such  waters  are  made  by  exca- 
vating or  embanking  the  soil,  and  then  hning  the  floor  and  sides 
with  concrete  or  well-puddled  clay;  common  mortar  must  not 
be  used,  as  the  water  takes  up  the  lime.  Their  position  should 
be  such  that  a  jet  reaching  20  feet  above  the  highest  house  to 
be  supplied  is  assured  by  gravitation  alone,  otherwise  the  water 
has  to  be  pumped  to  a  higher  elevation.  Means  are  generally 
taken  for  diverting  the  tributary  streams  from  the  storage 
reservoir  when  these  get  foul  in  times  of  flood,  by  means  of  a 
by- wash. 

The  size  of  a  storage  reservoir  for  a  catchment  area  will  depend 
upon  the  numbers  of  the  community  requiring  the  water,  and 
upon  the  mean  rainfall  of  the  district.  Hawksley's  formula  is 
of  value  in  estimating  the  number  of  days'  supply  {x)  which 
must  be  stored  when  a  community  is  dependent  on  a  rain- 
water supply.      In  this  formula  x= ;  where  jy=  the  mean 

rainfall  during  the  three  driest  consecutive  years — which  is 
usually  about  one-fifth  less  than  the  average.  In  this  country 
from  120  to  130  days'  supply  have  to  be  stored. 

The  average  annual  amount  of  evaporation  from  an  exposed 
body  of  water  reduces  the  depth  by  some  30  inches  over  the 
whole  surface;  therefore  there  is  an  advantage  in  diminishing 
the  exposed  area  of  the  water  by  constructing  deep  reservoirs, 
rather  than  shallow  ones. 

The  probable  daily  yield  (in  gallons)  of  a  catchment  area  (x) 
may  be  arrived  at  by  Dr.  Pole's  formula,  in  which 

a;=62  A/'^^Rm  -E 

In  this  formula  A=the  area  of  the  gathering  ground  in  acres; 
Rm  -  the  estimated  average  rainfall  of  the  three  driest  con- 
secutive years;  and  E=the  loss  of  rainfall  by  evaporation, 
percolation,  and  unavoidable  waste.  The  value  of  E  may  be 
as  little  as  10  inches,  and  may  even  exceed  20. 

Peaty  matter  is  very  frequently  present  in  the  upland  surface 


8  HYGIENE   AND   PUBLIC   HEALTH 

waters  of  mountainous  districts,  often  imparting  a  decidedly 
yellow  or  brownish  hue  to  the  water.  It  may  be  removed  by 
filtering  the  water  through  beds  of  fine,  sharp  sand,  as  is  done 
at  Vartry  (Dublin) . 

Under  the  heading  of  Upland  Surface  Waters  may  also  be 
considered  the  waters  derived  from  natural  lakes  in  mountainous 
districts,  of  which  Glasgow  furnishes  a  good  example.  Glasgow 
is  supplied  with  water  from  Loch  Katrine,  34  miles  north  of  the 
City.  This  beautifully  soft  and  pure  lake-water,  which  replaced 
in  1859  the  grossly-polluted  supply  drawn  from  the  Clyde,  has 
been  of  inestimable  advantage  to  Glasgow,  not  only  by  raising 
the  standard  of  health  of  its  inhabitants,  but  also  by  effecting 
an  enormous  saving  in  manufacturing  and  industrial  pursuits, 
from  the  fact  of  the  hardness  being  equivalent  to  only  one  grain 
of  chalk  per  gallon  of  the  water. 

Upland  surface  and  lake  waters,  in  their  comparative  free- 
dom from  mineral  matters,  approach  more  nearly  to  the 
composition  of  rain-water  than  water  derived  from  any  other 
source.  Many  of  the  manufacturing  towns  in  Lancashire  and 
Yorkshire  are  suppHed  with  upland  surface  waters. 

Manchester  has  lately  obtained  a  new  source  of  supply  from 
Thirlmere,  90  miles  from  the  City.  By  the  construction  of  a 
dam,  the  level  of  the  lake  has  been  much  raised,  and  its  storage 
capacity  increased.  Liverpool,  by  immense  engineering  works, 
has  impounded  the  waters  of  the  Vyrnwy,  in  Wales,  by  a  massive 
masonry  wall  built  across  a  narrow  part  of  the  valley,  creating 
an  artificial  reservoir  4I  miles  in  length  and  conveying  the  water 
a  distance  of  68  miles;  and  Birmingham  is  now  supplied  with 
water  from  the  upper  sources  of  the  Wye. 

Occasionally  the  water  of  lakes  and  open  reservoirs  becomes 
contaminated  by  the  growth  and  subsequent  decay  of  algae  and 
other  microscopic  organisms.  In  some  instances  so  abundant 
is  the  growth  of  the  organism  that  the  water  becomes  coloured 
red  or  green-blue,  according  to  the  nature  of  the  organisms, 
and  is  also  turbid  and  evil-smelUng.  Beyond  the  unpleasantness 
arising  from  the  odour  and  turbidity  of  the  water,  and  the 
disturbance  of  the  sand  filter-beds  when  the  reservoir  water  is 
subjected  to  filtration,  it  does  not  appear  that  this  contamination 
induces  any  injurious  effect  upon  the  health  of  the  consumer. 

Reservoirs  that  are  covered  over  and  protected  from  light 
arc  not  nearly  so  subject  to  the  growth  of  algaj. 


WATER  9 

The  quantity  of  water  that  can  be  collected  and  stored  in  an 
impounding  reservoir  amongst  hills  can  be  calculated  with  some 
approach  to  accuracy  if  the  area  of  the  catchment  basin,  the 
average  rainfall,  and  the  average  amount  of  percolation,  evapora- 
tion, and  flow  of  the  rainfall  off  the  surface,  are  known.  Records 
of  the  rainfall,  percolation,  etc.,  extending  over  a  long  series 
of  years  are  necessary  for  this  purpose.  The  loss  from  evapora- 
tion in  open  reservoirs  may  reach  to  J  of  an  inch  per  day  in 
summer,  the  average  throughout  the  year  varying  from  j'.^  to 
,V  of  an  inch  daily.  The  area  of  the  catchment  basin  or  gathering 
ground  can  be  ascertained  from  a  6-inch  ordnance  map.  It 
is  in  many  cases  a  district  enclosed  by  a  ridge  line,  which  is 
continuous  except  where  the  water  finds  exit;  or  if  the  ridge 
line  is  complete  and  the  water  does  not  find  an  exit,  a  lake  or 
natural  reservoir  is  formed.  The  main  ridge  line  may  give  off 
branches,  and  thus  produce  subsidiary  or  secondary  catchment 
basins. 

In  6-inch  ordnance  maps,  contour  lines,  which  are  fines  of 
equal  attitude,  are  drawn  at  every  25  feet  of  elevation.  Ridge 
lines,  or  watershed  lines,  indicate  where  the  ground  is  higher  than 
that  immediately  adjacent  on  each  side,  the  land  sloping  from 
them  on  both  sides.  On  the  ordnance  map  will  also  be  found 
the  Bench  Mark  figures,  which  indicate  in  feet  the  height  of  the 
particular  spot  above  ordnance  datum.  If  the  place  noted  by 
any  of  these  figures  be  visited,  there  will  be  found  a  B.  M.  or 
broad  arrow  marked  on  some  object,  such  as  a  milestone,  church- 
wall,  rock,  etc. 

The  maps  of  the  Ordnance  Survey  of  the  United  Kingdom  are  pubUshed 
in  the  following  scales:  (i)  |^  inch  to  the  mile,  or  o-jj^jo  the  actual  measure- 
ments of  the  ground.  This  map  shows  a  considerable  area  of  country 
in  one  sheet.  (2)  One  inch  to  the  mile,  or  ygijgy  the  actual  measurements 
of  the  ground.  This  is  the  general  road  raap  of  the  country.  The  out- 
line edition  shows  contours  at  100  feet  intervals  up  to  1,000  feet,  and 
above  that  height  at  250  feet  intervals,  and  numerous  spot  levels  along  the 
roads.  (3)  Six  inches  to  the  mile,  or  yo5«o  *^^  actual  measurements  of 
the  ground.  This  map  shows  houses  and  fields  and  boundary  lines. 
Altitudes  are  shown  as  on  the  2 5 -inch  map,  and  contours  are  shown  at 
50  ft.,  100  ft.,  and  at  100  ft.  intervals  up  to  1,000  ft.  above  sea  level. 
(4)  Twenty-five  inches  to  the  mile,  or  tt^^jo  the  actual  measurement?  of  the 
ground.  This  map  shows  the  details  of  buildings,  and  the  boundaries  and 
areas  of  fields,  etc.  It  shows  levels  of  bench  marks  along  the  roads  to  one 
place  of  decimals,  but  docs  not  show  contours.  (5)  Town  maps,  with  the 
exception  of  London,  Dublin,  Belfast,  and  some  smaller  towns,  are  on  the 
scale  of  lo-  56  feet  to  the  mile,  or  ^^ijy  the  actual  measurements  of  the  ground, 
for  all  towns  which  at  the  time  of  the  survey  had  4,000  inhabitants  and 
upwards.     The  scale  is  large  enough  to  show  doorsteps,  the  thickness  of 


10  HYGIENE    AND    PUBLIC   HEALTH 

walls,  and  the  divisions  between  buildings.  It  also  fhows  all  objects  con- 
nected with  water-supply,  lighting,  and  drainage,  such  as  hydrants,  lamp- 
posts, sewer-manholes,  and  gratings.  Levels  arc  shown  along  many  of  the 
streets,  and  bench  marks  showing  to  two  places  of  decimals  the  altitude 
above  mean  sea  level.  Areas  are  not  shown  on  town  plans,  nor  are  con- 
tours. In  London,  Dublin,  and  Belfast  the  scale  adopted  is  5  feet  to  the 
mile,  or  yoVo  ^^^'^  actual  measurements  of  the  ground. 

The  altitudes  on  the  maps  are  those  above  ordnance  datum  or  mean 
sea-level  at  Liverpool,  which  is  0-65  feet  below  the  mean  level  of  the  sea 
round  the  coast.  Trinity  high-water  mark  at  the  entrance  of  the  London 
Docks  is  12-48  feet  above  ordnance  datum.  Surface  levels  are  shown  in 
feet  along  the  roads  on  the  6-inch  maps  thus  +  :  on  lo-feet  town  plans 
one  decimal  is  given.  Altitudes  are  shown  thus  "^B.  M.  S7'4-"  B.  M. 
means  the  Bench  Mark  cut  on  buildings,  walls,  etc.,  and  at  this  spot  the 
Bench  Mark  is  57-4  feet  above  ordnance  datum. 

Waters  collected  from  upland  surfaces  are  liable  to  pollution 
from  shepherds'  huts  and  the  droppings  of  animals  allowed  to 
feed  upon  the  collecting  area.  The  water  collected  upon  these 
areas  ought  always  to  be  carefully  protected  from  such  pollutions. 

Streams  and  Rivers. 

Streams  near  their  sources,  and  passing  through  uncultivated 
land  on  hills  and  moorlands  devoid  of  human  habitations,  are 
good  sources  of  water-supply;  they  form,  in  fact,  those  upland 
surface  waters  which  have  already  been  considered. 

Streams  and  rivers  in  their  course  through  cultivated  valleys, 
with  towns  and  villages  on  their  banks,  furnish  water  which 
must  always  be  regarded  as  undesirable,  and  in  many  cases  as 
dangerous  for  drinking  purposes. 

The  composition  of  river  water,  as  regards  its  mineral  in- 
gredients, is  most  variable.  Fed  from  a  variety  of  sources,  by 
springs  and  streams  in  the  uplands,  by  surface  drainage,  by 
springs  in  their  beds,  and  by  other  streams  and  rivers  through- 
out the  whole  of  their  course,  rivers  are  a  combination  of  spring 
and  surface  waters,  and  present  sometimes  mainly  the  char- 
acteristics of  the  one  and  sometimes  those  of  the  other. 

All  rivers,  as  being  the  natural  drainage  channels  of  the  sur- 
rounding land,  must  be  subject  to  pollutions  of  animal  origin. 
The  surface  and  subsoil  drainage  from  manured  land  under  culti- 
vation, the  sewage  effluents  from  isolated  houses,  the  slop  waters 
and  the  sewage  of  villages  and  sometimes  even  of  towns,  and  the 
waste  products  of  industries  on  their  banks  frequently  flow  into 
the  river.  Towns,  as  a  rule,  draw  their  supply  of  water  from 
a  river  above  the  spot  at  which  the  sewage  of  the  town  is  dis- 
charged.    But  the  intake  of  the  next  lower  town  on  the  banks 


WATEK  II 

of  that  river  must  necessarily  be  from  a  stream  already  polluted 
with  sewage;  and  the  question  arises,  can  a  river  once  polluted 
with  sewage,  and  with  all  the  possibilities  of  specific  disease 
contamination  thereby  introduced,  ever  be  a  safe  source  of 
supply  below  the  point  of  pollution  ? 

When  sewage  or  other  polluting  liquids  are  discharged  into 
rivers,  they  are  more  or  less  diluted  with  the  river  water,  the 
amount  of  dilution  depending  on  the  comparative  volumes  of 
sewage  and  river  water  which  are  thus  mixed  together.  If  the 
river  into  which  the  sewage  is  discharged  consists  of  clean  and 
hitherto  unpolluted  water,  the  oxygen  dissolved  in  it  will,  to 
a  certain  extent,  oxidize  the  organic  matters  of  the  sewage, 
this  destruction  being  very  largely  effected  through  the  agency 
of  aerobic  or  oxygen-requiring  bacteria.  If,  too,  the  dilution  of 
the  sewage  with  clean  water  is  considerable,  plant  life  is  not 
interfered  with  but  continues  to  give  off  oxygen,  reoxygenating 
the  water,  and  enabling  the  process  of  purification  by  oxidation 
to  continue.  No  doubt,  also,  as  the  oxygen  dissolved  in  the 
water  is  used  up,  fresh  oxygen  is  absorbed  from  the  air.  Besides 
water  plants,  minute  animals  (infusoria,  anguillulidae  or  water 
worms,  entomostraca  or  water  fleas,  etc.)  aid  the  process  of 
purification  by  feeding  on  the  organic  impurities  of  sewage. 
These  organisms  are  found  in  countless  numbers  in  the  polluted 
reaches  of  rivers.  Fish,  too,  if  the  pollution  is  not  sufficiently 
great  to  cause  serious  diminution  of  dissolved  oxygen  in  the 
water,  feed  on  some  of  the  elements  of  sewage,  and  aid  in  the 
process  of  purification;  and  when  the  current  is  sluggish,  or 
in  the  deep  and  quiet  pools  of  a  rapid  stream,  the  suspended 
matters  of  the  sewage  will  be  largely  deposited. 

Delepine  has  shown  that  this  sedimentation,  which  occurs 
when  the  flow  is  sluggish,  is  a  very  important  factor  in  promoting 
bacterial  purification  in  river  water. 

The  result  of  all  these  processes  is  that,  under  certain  con- 
ditions and  within  certain  limits,  streams  and  rivers  which 
have  been  polluted  are  capable  of  undergoing  a  certain  amount 
of  self-purification  by  natural  means.  The  Rivers  Pollution 
Commissioners  (Sixth  Report)  came  to  the  conclusion,  as  the 
result  of  their  experiments,  that  "  the  oxidation  of  the  organic 
matter  in  sewage  proceeds  with  extreme  slowness,  even  when 
the  sewage  is  mixed  with  a  large  volume  of  unpolluted  water, 
and  that  it  is  impossible  to  say  how  far  such  water  must  flow 


12  HYGIENE   AND    PUBLIC   HEALTH 

before  the  sewage  matter  becomes  thoroughly  oxidized.  It 
will  be  safe  to  infer,  however,  from  the  above  results,  that  there 
is  no  river  in  the  United  Kingdom  long  enough  to  effect  the 
destruction  of  sewage  by  oxidation." 

The  truth  of  the  matter  then  appears  to  be,  that  under  favour- 
able conditions,  when  the  dilution  of  the  sewage  with  clean 
water  is  very  considerable  and  the  oxidation  and  purification 
exerted  by  aquatic  animal  and  vegetable  life  can  have  free 
play,  a  stream  or  river,  especially  if  it  undergoes  agitation  and 
exposure  to  the  air  by  flowing  over  rapids  or  by  falling  over 
weirs,  is  capable  of  being  so  far  purified  that,  although  it  may 
never  quite  regain  its  original  purity,  it  becomes  at  least  very 
much  improved. 

The  oxidation  of  the  organic  matters  in  sewage  is  not,  how- 
ever, the  only  process  with  which  the  self-purification  of  rivers  is 
concerned.  Of  more  importance  is  the  destruction  or  elimination 
of  the  bacterial  organisms  introduced  into  the  water  by  the 
polluting  agents,  more  especially  of  those  of  "  intestinal  type," 
e.g..  Bacillus  coli,  Bacillus  enteritidis  sporogenes,  Bacillus  enteri- 
tidis  (Gaertner),  and  streptococci,  with  which  are  occasionally 
associated  the  Bacillus  typhosus  and  other  pathogenic  organisms. 
It  is  probable  that  organisms  of  this  type  may  persist  in  a 
polluted  water  which  has  freed  itself  from  all  other  evidence 
of  sewage  contamination,  and  be  present  in  such  numbers  as 
to  indicate  recent  contamination  with  animal  matter  with  all 
its  attendant  dangers.  There  is  evidence  that  organisms  of 
the  intestinal  type,  after  obtaining  admission  to  water,  undergo 
after  a  time  changes  of  a  degenerative  nature,  probably  accom- 
panied by  loss  of  virulence,  so  that  they  no  longer  comply  with 
all  the  tests  characteristic  of  the  types  they  represent. 

When  the  river  into  which  sewage  is  discharged  is  already  much 
polluted,  or  if  the  dilution  is  not  sufficiently  great,  oxidation  and 
purification  are  brought  to  a  standstill.  The  dissolved  oxygen 
is  then  greatly  diminished  in  amount;  many  forms  of  animal 
and  vegetable  aquatic  Ufe  are  injuriously  affected  or  destroyed; 
decomposition  or  fermentation  of  organic  matters  is  started, 
with  the  production  of  foul  gases;  the  bed  of  the  river  becomes 
silted  up  with  decaying  matters,  which,  buoyed  up  by  gases, 
occasionally  rise  to  the  surface  and  sink  again,  and  a  most  serious 
nuisance  results.  The  process  is  one  eventually  tending  to 
purification  by  resolution  of  complex  organic  bodies  into  their 


WATER  13 

simpler  elements,  but  in  the  meantime  the  effects  of  the  process 
are  most  offensive. 

A  considerable  rise  of  temperature  will  produce  a  like  result 
on  rivers  which  are  having  their  purifying  powers  tested  to  the 
height  of  their  capacity.  Purification  goes  on  so  long  as  the 
weather  is  cool,  but  with  a  rise  in  temperature,  certain  forms 
of  bacterial  growth  are  stimulated  and  decomposition  sets  in, 
replacing  the  oxidizing  processes. 

Sewage  in  drinking  water  is  chiefly  dangerous  from  the  fact 
of  its  being  liable  to  contain  the  specific  poisons  of  disease. 
Cholera  and  enteric  fever,  diarrhoea  and  dysentery,  we  know 
to  be  sometimes  spread  by  means  of  infected  and  polluted 
water. 

A  considerable  mass  of  evidence,  based  largely  on  1  h  oratory 
experiments,  was  submitted  to  the  Royal  Commission  on  Metro- 
politan Water  Supply  (1893),  as  to  the  behaviour  in  water  of 
the  bacilli  of  typhoid  fever  and  cholera.  The  statements  of 
the  bacteriological  witnesses  before  the  Commission,  therefore, 
represent  knowledge  obtained  under  artificial  conditions  of 
disease  organisms  cultivated  under  such  conditions,  and  are 
consequently  only  inferentially  apphcable  to  similar  microbes 
in  a  state  of  nature  and  subjected  to  a  natural,  as  opposed  to 
an  artificial,  environment. 

With  this  reservation,  the  general  results  of  the  bacteriological 
evidence  may  be  summed  up  as  follows:  The  bacilli  of  typhoid 
fever  and  cholera  tend  to  lose  their  vitality,  and  ultimately  to 
disappear,  when  placed  in  water.  In  water  which  is  sterile,  or 
devoid  of  other  organisms,  these  bacilli  may  retain  some  kind  of 
vitality  for  several  weeks  or  months  if  the  water  contains  organic 
pabulum.  But  in  water  containing  actively  growing  non- 
pathogenic organisms,  such  as  ordinary  river  water,  the  destruc- 
tion of  the  pathogenic  organisms  is  effected  much  more  rapi  ly. 
This  statement  helps  to  throw  fight  on  certain  outbreaks  of 
enteric  fever  due  to  specific  contamination  of  deep  well-water. 
Pure  deep  well-waters  contain  relatively  few  bacteria;  conse- 
quently the  typhoid  bacillus  when  introduced  into  such  a  water 
(as  occurred  in  the  Caterham  outbreak)  may  possibly  retain  its 
vitality  and  virulence  sufficiently  long  to  render  large  volumes 
of  water  infective.  It  appears  possible,  also,  that  under  such 
conditions,  deep  underground,  with  an  absence  of  light,  the 
typhoid  bacillus  for  a  space  of  two  or  three  days  might  increase 


14  HYGIENE   AND   PUBLIC   HEALTH 

in  numbers,  thus  enabling  a  relatively  small  amount  of  polluting 
ingredient  to  contaminate  large  volumes  of  water. 

The  process  of  sedimentation  which  occurs  in  the  deep  and 
sluggish  reaches  of  a  river  tends  to  the  eUmination  of  bacteria, 
the  suspended  matters  in  their  subsidence  entangling  them 
and  carrying  them  down.  The  effect  of  aeration  and  of  flow 
are  less  apparent  quel  bacterial  destruction;  whilst  as  regards 
the  undoubted  powerful  germicidal  action  of  bright  sunlight, 
in  the  case  of  a  river  like  the  Thames,  with  an  average  depth 
of  over  six  feet,  it  is  doubtful  what  effect  the  water  has  in  cutting 
off  the  actinic  light,  and,  therefore,  what  is  the  precise  germi- 
cidal action  of  sunUght  or  daylight  at  different  depths  from  the 
surface,  and  under  different  conditions  of  clearness  or  turbidity 
of  the  water. 

Dr.  Houston  has  shown  that  if  sufficient  storage  capacity  is 
provided  in  the  reservoirs  for  the  crude  river  (Thames)  water 
from  the  intakes,  it  is  possible  to  eliminate  from  the  water  all 
but  a  very  small  percentage  of  disease-producing  organisms.  In 
eighteen  experiments  with  unfiltered  water,  infected  with  enor- 
mous numbers  of  the  bacilli  of  enteric  fever,  it  was  found  that 
over  99  per  cent,  of  these  organisms  died  as  the  result  of  simple 
storage  of  the  water  for  four  weeks.  The  final  and  complete 
disappearance  of  typhoid  bacilli  from  an  artificially  infected 
raw  river  water  may  not  take  place  until  nine  weeks  after 
inoculation. 

The  process  of  storage  and  purification  of  Thames  water 
pursued  by  the  Metropolitan  Water  Board,  on  the  efficiency  of 
which  the  health  and  freedom  from  disease  of  so  large  a  popula- 
tion depends,  is  as  follows: — 

The  water  taken  from  the  river  is  passed  into  a  storage  reser- 
voir, capable  of  holding  several  days'  supply.  It  is  important 
that  the  capacity  of  this  reservoir  should  be  sufficiently  great, 
both  to  obviate  the  necessity  of  drawing  water  from  the  river 
when  it  is  in  flood  (and  therefore  very  turbid),  and  to  allow  time 
for  the  clarification  of  the  water  by  the  deposition  of  suspended 
matter.  From  the  storage  reservoirs  the  water  is  conducted  to 
the  surface  of  the  filter  beds,  which  consist  of  layers  of  fine  sand 
(average  thickness  3  feet)  lying  upon  layers  of  gravel,  fine  above 
but  coarse  below,  and  of  a  total  depth  varying  from  3  to  8  feet. 
The  average  fiJtering  area  per  million  gallons  of  daily  supply  is 
079  acre.     In  the  coarse  gravel  or  rough  stones  are  the  open 


WATER  15 

mouths  of  the  outlet  pipes,  which  convey  the  filtered  water  from 
the  filter  beds  to  a  central  ftltered-watcr  well,  from  whence  it  is 
pumped  through  iron  mains  to  the  Metropolis,  or  to  a  high-level 
reservoir  near  London.  Vents  run  up  from  the  deeper  layers 
of  the  filters  to  above  the  water  level  to  permit  of  the  escape  of 
displaced  air  when  the  bed  is  being  filled  with  water.  The  large 
reservoirs  for  the  storage  of  filtered  water  in  or  near  towns  should 
be  covered;  they  are  not  infrequently  made  to  feed  supplemen- 
tary reservoirs,  especially  where  the  demand  in  one  part  of  the 
district  greatly  exceeds  the  average  for  the  district  generally. 

The  depth  of  water  on  the  filter  beds  is  never  more  than 
2  feet,  the  average  rate  of  filtration  per  square  foot  of  filter  bed 
being  i|  gallons  per  hour,  or  1,568,160  gallons  per  acre  in 
24  hours.  The  upper  layers  of  fine  sand  must  be  occasionally 
renewed,  as  they  become  choked  with  sediment.  The  old  sand 
is  washed  with  water  jetted  from  a  hose  under  high  pressure, 
before  being  used  again  in  the  filter  beds. 

Houston  has  shown  that  in  fresh,  healthy,  human  f?eces 
85  per  cent,  of  the  organisms  known  as  Bacilli  coli  communis  are 
typical  B.  coli,  answering  to  all  the  known  tests  for  this  organism, 
the  remaining  15  per  cent,  being  atypical,  in  the  sense  that 
they  do  not  respond  to  all  the  tests.  In  sewage  and  sewage 
effluents  the  percentage  of  typical  B.  coli  is  slightly  reduced, 
and  in  sewage  polluted  waters  there  is  a  further  reduction. 
In  filtered  waters  derived  from  polluted  sources,  such  as  the 
water  of  the  Thames  at  Hampton,  the  percentage  of  typical 
bacilli  is  reduced  as  low  as  38  after  storage  and  sand  filtration, 
such  as  is  practised  by  the  Metropolitan  Water  Board,  in  addi- 
tion to  the  98  per  cent,  reduction  in  total  number  of  organisms 
as  compared  with  the  unfiltered  crude  river  water.  Dr.  Houston 
is  of  opinion  that  the  smaller  proportion  of  typical  B.  coli  in 
the  stored  and  filtered  water  is  evidence  of  elimination  from  the 
water  of  bacilli  which  are  specially  characteristic  of  faecal  matter; 
and  therefore  of  purification  by  change  of  type  of  baciUi,  apart 
from  reduction  in  numbers.  The  elimination  of  the  typical 
bacilli  is  relative  and  not  absolute,  as  30  per  cent,  of  the  samples 
of  filtered  water  analyzed  contained  typical  B.  coli  either  in 
100  c.c.  (15  per  cent.),  10  c.c.  (11  per  cent.),  or  i  c.c.  (4  per 
cent.)  of  the  water.  In  the  latter  case  only,  however  (jB.  coli 
present  in  i  c.c),  would  the  water  be  considered  decidedly 
unsatisfactory. 


l6  HYGIENE   AND    PUBLIC   HEALTH 

Thus  it  appears  that  even  river  water  which  has  received 
some  sewage  contamination  may  be  made  reasonably  safe  for 
drinking  purposes  by  storage  followed  by  sand  filtration  ;  but 
every  care  must  be  exercised  to  insure  the  continuous  working 
efficiency  of  each  filter  in  use,  and  to  guard  against  subsequent 
contamination  of  the  water. 

Sand  acts  almost  entirely  as  a  mechanical  filter,  but  a  small 
amount  of  purification  by  oxidation  takes  place.  This  purifi- 
cation results  mainly  from  the  condensation  of  oxygen,  which 
takes  place  upon  the  upper  surface  of  the  sand.  Dr.  Percy 
Frankland  has  shown  that  the  micro-organisms  (harmless)  present 
in  unfiltered  Thames  water  at  Hampton  are  reduced  in  number  on 
the  average  97 7  per  cent,  by  the  sedimentation  and  filtration  which 
the  water  undergoes  at  the  hands  of  the  Water  Board,  and  that 
this  reduction  is  largest  in  the  case  of  those  installations  which  have 
the  largest  storage  capacity  for  unfiltered  water,  and  the  slowest 
rate  of  filtration,  these  being  factors  of  much  influence  on  the 
chemical,  as  well  as  on  the  biological,  characteristics  of  the  water. 

All  the  witnesses  before  the  Royal  Commission  on  the  Metro- 
pohtan  Water  Supply  (1893)  were  agreed  that  the  efficiency  of 
the  sand  filter  beds  in  intercepting  bacteria  is  due  to  the  forma- 
tion of  a  superficial  gelatinous  deposit  on  the  top  of  the  sand. 
Green  and  blue  algge  interweave  their  filaments  into  one  felted 
sheet;  diatoms,  with  their  siliceous  frustules  and  gelatinous 
envelopes,  fill  up  the  meshes;  zooglea  adhere  to  every  particle; 
and  innumerable  bacteria  dot  the  whole  mass  (Thresh).  The 
bacteria  become  attached  to  and  entangled  in  the  colloidal  mass, 
and  are  consequently  prevented  from  passing  down  into  the 
deeper  beds  of  sand  and  gravel.  This  filtration  has  been  likened 
to  the  dialysis  through  a  fine  jelly,  which  is  capable  of  inter- 
cepting the  very  smallest  bacteria,  if  there  is  no  rupture  or  loss 
of  continuity  in  the  material.  This  gelatinous  film  which  forms  on 
the  top  layer  of  sand  consists  therefore  very  largely  of  intercepted 
organic  matter  and  bacteria.  It  appears  to  be  sufficientl}^  well 
formed  to  be  effective  in  intercepting  bacteria  within  two  or 
three  days  after  the  filter-bed  has  been  in  use,  subsequent  to 
renewal  of  the  top  layer  of  sand.  It  follows,  therefore,  that 
the  filter-bed  does  not  attain  its  normal  efficiency  in  the  inter- 
ception of  bacteria  until  it  has  been  in  use  at  least  two  days 
after  the  periodical  renewal.  On  the  other  hand,  there  is  no 
evidence  of  the  efficiency  of  the  sand  filter-beds,  qua  bacterial 


WATER  17 

interception,  being  reduced  by  prolonged  use,  even  for  so  ex- 
tended a  period  as  sixty-eight  days.  It  would  seem  that  the 
organisms  tend  to  grow  down  deeper  and  deeper  into  the  beds, 
and  might  possibly  in  time  grow  quite  through  the  interstices 
of  the  filter,  and  so  reappear  in  the  filtered  water.  But  owing 
to  the  thickness  of  sand  this  process  must  occupy  a  very  long 
time.  The  reason  why  the  top  layers  of  sand  should  be  removed 
and  renewed  periodically  is  to  prevent  other  filter-beds  being 
overtaxed,  because  the  filtration  becomes  slow  in  old  beds, 
owing  to  the  thickness  of  the  gelatinous  coating,  and  consequent 
clogging  of  the  top  layers.  If  certain  filter-beds  are  working 
too  slowly,  others  have  to  be  pressed,  possibly  resulting  in 
inefficient  filtration,  in  order  to  make  up  the  volume  of  filtered 
water  necessary  for  the  daily  supply. 

The  result  of  the  Massachusetts  experiments  on  the  purifica- 
tion of  water  by  filtration  may  be  briefly  summarized  as 
follows: — 

(fl)  By  reducing  the  rapidity  of  filtration,  and  employing  the 
finer  sands,  increased  efficiency  is  obtained. 

{b)  With  moderate  rapidity  of  filtration  (2,000,000  gallons 
per  acre  per  diem)  i  foot  of  sand  appears  to  be  as  effective 
as  5. 

(c)  The  scraping  off  of  the  upper  layer  of  clogged  sand  enables 
more  organisms  to  pass  through  the  filter;  and  it  is  not,  as  a 
rule,  until  three  days  after  scraping  that  the  filters  regain  their 
highest  efficiency. 

{d)  Fifty-five  per  cent,  of  the  organisms  removed  were  found 
in  the  upper  ^  inch  of  sand,  and  80  per  cent,  in  the  upper  inch. 

{e)  Much  less  water  at  32°  F.  passes  through  a  filter  than  when 
the  water  is  at  70°  F.,  owing  to  the  increased  viscosity  of  the 
colder  water. 

(/)  Shallow  filters  require  more  frequent  scraping  than  the 
deeper  ones,  due  to  the  greater  head  available  in  the  deeper 
filters. 

(^)  Filters  used  continuously  require  less  frequent  scraping 
than  when  used  intermittently. 

The  connection  between  the  cholera  outbreak  in  Hamburg 
in  1892  and  its  water  supply,  and  the  value  of  sand  filtration 
are  clearty  demonstrated  by  the  following  facts: — Hamburg, 
Altona,  and  Wandsbeck  are  three  towns  which  are  contiguous 
to  each  other,  and  really  form  a  single  community,  not  differing 


l8  HYGIENE  AND   PUBLIC  HEALTH 

from  each  other  except  in  so  far  that  each  has  a  separate  and 
different  kind  of  water  supply.  Wandsbeck  obtained  filtered 
water  from  a  lake  which  is  hardly  at  all  exposed  to  contamination 
with  faecal  matter;  Hamburg  obtained  its  water  unfiltered  from 
the  tidal  Elbe  above  the  town ;  whilst  Altona  drew  its  water  from 
the  Elbe,  but  below  Hamburg,  after  the  river  had  received  the 
sewage  of  800,000  people.  The  water  so  taken,  however,  was 
subjected  to  careful  sand  filtration,  before  being  supplied  to 
the  people  of  Altona.  Whereas  Hamburg  in  1892  was  severely 
visited  by  cholera,  nearly  17,000  attacks  and  8,600  deaths 
occurring  in  the  autumn  of  1892,  Wandsbeck  and  Altona  were 
nearly  free  from  the  disease.  About  500  cases  of  cholera 
occurred  in  Altona,  but  at  least  400  of  these  were  infected  in 
Hamburg,  The  water  supplied  to  Hamburg  was  taken  from 
the  Elbe  above  the  sewage  outfalls  into  the  river,  but  was 
nevertheless  contaminated  at  times  by  the  tidal  action  carrying 
sewage  back  above  the  outfalls.  This  water,  supplied  in  an 
unfiltered  condition  to  the  population,  was  the  cause  of  the 
cholera  epidemic.  Careful  sand  filtration  of  the  Elbe  water,  in 
a  much  more  grossly  sewage-polluted  condition,  saved  Altona 
from  the  disastrous  epidemic  which  raged  in  Hamburg. 

Professor  Koch  laid  stress  upon  the  following  three  points  as 
to  the  efficacy  of  sand  filtration:  (i)  That  a  proper  thin  layer 
of  mud  or  slime  should  be  formed  on  the  top  of  the  filter-bed; 
that  it  should  not  be  disturbed  during  the  process  of  filtration, 
and  that  when  the  deposit  becomes  too  thick  and  impermeable 
it  should  be  removed;  (2)  that  the  thickness  of  sand  should 
never  be  less  than  30  cm.  (ii-8  inches);  (3)  that  the  downward 
movement  of  the  water  through  the  sand  layer  must  not  exceed 
100  mm.  (3-94  inches)  in  the  hour,  or  a  Httle  over  2,000,000 
gallons  per  acre  per  diem.  He  recommends  that,  after  a  filter 
has  been  scraped,  the  slimy  deposit  should  first  be  allowed  to 
form  before  the  water  is  conducted  to  the  filtered-water  well  or 
reservoir;  that  each  separate  filter  should  be  bacteriologically 
investigated  daily,  and  water  containing  more  than  100  germs, 
capable  of  development  in  a  cubic  centimetre,  should  not  be 
allowed  to  reach  the  pure  water  reservoir.  The  majority  of  the 
bacteria  in  adequately  filtered  water  are  attributable  to  post- 
filtration  sources,  the  filter-beds  below  the  slime  layer,  the 
channels,  collecting  drains,  culverts,  and  wells  being,  of  course, 
not  sterile.     The  shghtest  disturbance,  however,  in  the  process 


WATER  ig 

of  filtration,  as,  for  instance,  the  quickening  of  the  pace  of  filtra- 
tion to  over  100  mm.  per  hour,  or  the  disturbance  of  the  slimy 
covering,  as  in  periods  of  frost  or  immediately  after  a  filter  is 
cleaned,  tends  to  create  an  immediate  increase  of  germs  in  the 
filtered  water. 

The  mechanical  filtration  of  water  under  pressure  provides 
a  rapid  means  of  filtering  large  volumes  of  water.  In  the 
pressure  filter  the  water  is  forced  under  pressure  through 
several  feet  of  fine  sand  or  quartz,  the  cleaning  of  the  filters 
being  effected  by  means  of  a  reversed  current  of  water.  Other 
materials  are  sometimes  used,  such  as  a  black,  porous,  magnetic 
oxide  of  iron,  called  Polarite.  These  filters  can  be  used  with 
or  without  coagulant,  but  in  the  former  case  a  satisfactory 
bacterial  standard  of  purity  cannot  be  obtained.  The  coagu- 
lant most  commonly  used  is  the  sulphate  of  alumina,  from 
I  to  2  grains  per  gallon;  and  the  object  of  its  employment  is  to 
form  a  gelatinous  cover  on  the  surface  of  the  mechanical  filter 
which  will  take  the  place  of  the  bacterial  scum  which  forms  on 
ordinary  sand  filters.  These  filters,  employed  in  conjunction 
with  a  coagulant,  are  very  serviceable  when  deahng  with  raw 
river  waters. 

The  conclusion  that  we  may  come  to,  then,  in  the  case  of  the 
London  water  supply  from  the  Thames,  is,  that  as  long  as  it  is 
efficiently  filtered  and  not  taken  from  the  river  when  in  flood,  it 
is  fairly  pure  and  reasonably  wholesome ;  but  that  the  Thames  is 
not  really  a  safe  source  of  supply,  for  should  the  filtering  arrange- 
ments break  down  at  a  period  of  epidemic  prevalence  in  the 
upper  reaches  of  the  river,  disease  would  in  all  probability  arise 
amongst  the  consumers  of  the  water  in  London.  The  sapie  may 
be  said  of  any  other  polluted  river  used  as  a  source  of  drinking 
water;  and  all  attempts  to  purify  by  filtration  organically 
polluted  water,  whether  it  be  on  a  public  or  a  domestic  scale, 
ought  to  be  deprecated. 

The  yield  of  a  small  stream,  or  water-course,  may  be  approxi- 
mately ascertained  by  observing  the  average  width  and  depth 
of  the  stream  over  a  portion  of  the  channel  where  it  is  fairly 
uniform.  The  yield  is  found  by  multiplying  the  area  thus 
obtained  by  four-fifths  of  the  surface  velocity  in  this  portion  of 
the  channel.  Current  meters  may  also  be  employed;  or,  if 
the  whole  stream  is  dammed  up  and  made  to  pass  through  a 
trough  of  known  area  and  length,  through  a  sluice  of  known 


20  HYGIENE   AND   PUBLIC    HEALTH 

size,  or  over  a  weir  in  which  a  rectangular  notch  of  known  area 
is  cut,  the  discharge  of  water  can  be  very  accurately  estimated. 
It  is  only  necessary  to  multiply  the  sectional  area  (in  square  feet) 
of  the  trough  or  sluice  by  the  velocity  of  the  water  (also  in  feet), 
to  ascertain  the  number  of  cubic  feet  of  water  being  discharged. 
When  water  is  taken  from  the  head  of  a  stream  for  municipal 
purposes,  a  "  compensation  reservoir "  is  often  provided  to 
impound  storm  waters,  which  can  be  led  into  the  river  for  trade 
purposes  to  augment  the  dry- weather  flow. 

Sometimes  river  water  is  obtained  from  deep  trenches  dug  in 
the  proximity  of  a  river,  and  it  is  assumed  that  the  water  under- 
goes purification  in  its  passage  through  the  soil.  Although  more 
or  less  ground  water  is  generally  collected  in  these  trenches,  water 
of  great  purity  has  often  thereby  been  obtained. 

Springs. 

The  advantages  of  underground  water  supplies  over  surface- 
collected  supplies  are  that  large  reservoirs  are  not  required, 
less  land  is  wanted,  filtration  is  unnecessary,  and  there  is  less 
liability  to  pollution.  In  some  springs,  derived  from  under- 
ground waters  at  great  depths  below  the  surface  of  the  earth, 
the  mineral  constituents  of  the  water  are  so  excessive  in  amount 
as  to  render  it  quite  unfit  for  drinking,  but  valuable  for  medicinal 
purposes.  There  can  be  little  doubt  that  the  water  forming 
these  springs  is,  in  many  cases,  forced  out  of  the  earth  by  the 
pressure  of  confined  gases;  but  the  origin  of  most  of  the  springs 
which  afford  a  pure  and  wholesome  water  for  ordinary  use  is 
explained  in  a  different  manner. 

The  rain  which  percolates  the  porous  strata  (sand,  gravel, 
fissured  chalk,  sandstone,  etc.),  at  the  surface  of  the  earth,  sinks 
through  these  strata  by  the  force  of  gravity  until  it  reaches — 
as  it  usually  does  at  a  greater  or  less  depth — an  impermeable 
stratum.  This  underground  water  does  not  always  stand  at 
the  same  level.  It  is  constantly  rising  and  sinking,  and  in  most 
years  these  variations  of  level  are  fairly  regular,  both  as  to 
amount  and  as  to  the  season  of  the  year  at  which  they  occur. 
The  highest  level  is  usually  reached  in  this  country  in  February 
or  March,  whilst  the  lowest  occurs  in  October  or  November. 
The  cause  of  these  variations  must  be  looked  for  in  the  cir- 
cumstances attending  the  rainfall. 

In  districts  having  an  average  rainfall  (25  to  30  inches  per 


WATER  21 

cinnum),  tlie  amounts  of  rain  that  fall  in  summer  and  in  winter 
are  very  nearly  equal.  But  in  the  summer  months  (April  to 
September)  the  amount  of  rain  that  percolates  is  generally  very 
small;  it  is  only  one-seventh  of  the  summer  rainfall  in  chalky  soil. 
Nearly  all  the  rain  that  falls  in  an  average  summer  is  evaporated 
from  the  surface  of  the  soil  or  from  the  leaves  of  plants.  The 
consequence  is  that  the  underground  water  is  not  replenished 
from  the  surface,  and  its  level  sinks.  In  the  winter  months 
(October  to  March)  considerably  more  than  half  the  rainfall 
percolates  in  most  chalky  soils,  the  remainder  being  lost  by 
evaporation.  The  underground  water  begins  to  rise  usually  in 
November,  if  percolation  has  commenced  in  October,  and  con- 
tinues to  rise  until  it  attains  its  maximum  in  March. 

Occasionally  it  happens,  as  in  1879  and  in  1903  when  the 
summers  were  very  wet,  that  the  underground  water  rises  during 
the  summer  months.     But  such  years  are  exceptional. 

The  underground  water  is  not  only  constantly  changing  its 
level,  but  it  is  also  always  moving  slowly  towards  its  natural 
outlet.  The  water  tends  to  find  its  own  level  according  to  the 
laws  of  gravitation ;  not  rapidly,  but  slowly,  owing  to  the  friction 
and  capillarity  which  obstruct  its  passage  through  the  interstices 
of  the  rocks  or  soil.  The  outlet  may  be  into  the  sea  or  into  a 
river,  or  by  springs. 

It  has  been  found  by  observation  on  shallow  wells  that  the 
underground  water  has  a  curved  surface  from  its  highest  level 
to  its  outlet.  The  curve  lises  steeply  from  the  outlet,  but 
gradually  becomes  more  nearly  horizontal  as  the  distance  from 
the  outlet  increases  (fig.  i).  The  variations  in  level  between  high 
and  low  underground  water  are  small  near  the  outlet,  whilst 
they  gradually  increase  as  the  distance  from  the  outlet  increases. 
When  the  level  of  the  underground  water  is  highest,  the  fall 
to  the  outlet  is  greatest,  and,  consequently,  the  volume  of  water 
discharged  at  the  outlet  is  at  its  maximum. 

Springs  are  usually  divided  into  "  main  or  deep  "  and  "  land  " 
springs.  Land  springs  are  formed  by  the  "  cropping  out  "  on 
the  surface  of  the  earth  of  the  impermeable  stratum  which  holds 
the  underground  water  up,  i.e.  prevents  it  from  sinking  further 
into  the  earth. 

Such  springs  are  the  outlets  of  limited  collections  of  under- 
ground water,  formed  in  superficial  beds  of  sand  or  gravel  over- 
lying an  impermeable  stratum.     They  are  often  intermittent. 


22  HYGIENE    AND    PUBLIC   HEALTH 

ceasing  altogether  to  flow  during  the  summer,  when  the  under- 
ground water  is  exhausted,  and  beginning  again  in  the  autumn, 
very  soon  after  percolation  commences.  Intermittent  springs 
are  also  formed  where  a  valley  cuts  across  the  highest  levels 
of  a  large  volume  of  underground  water,  so  that  the  spring  flows 
only  for  a  short  period  of  every  year — usually  in  February  or 
March — when  the  highest  water  line  of  the  underground  water 
is  tapped  by  the  depression  of  the  valley  (fig.  i) . 

Main  springs  are  the  deep-seated  springs  issuing  through  a 
fault  or  fissure  from  regular  geological  formations,  such  as  chalk, 
oolite,  sandstone.  They  are  usually  perennial,  flowing  all  the 
year  round,  but  often  exhibit  well  marked  seasonal  variations, 
their  volume  increasing  in  winter,  when  the  underground  water 
level  stands  highest  {see  fig.  i). 

Springs  afford  good  sources  of  water  supply  for  small  com- 
munities, such  as  villages.     Main  springs  are  better  than  land 


Fig.  I. — Underground  Water  Curves. 

A,  high  level;  B,  low  level;  C,  intermittent  land  spring;  D,  constant  land 
spring  at  sea  level. 

springs,  both  because,  as  before  stated,  they  yield  water  through- 
out the  entire  year,  and  because  they  are  less  liable  to  accidental 
pollutions,  the  great  thickness  of  strata  through  which  the  water 
percolates  from  the  surface  effectually  dealing  with  any  organic 
impurities  it  may  contain.  Such  spring  water  is  usually  clear 
and  sparkUng,  well  aerated,  and  of  nearly  constant  temperature 
throughout  the  year.  It  generally  contains  more  or  less  of  the 
salts  producing  hardness,  and  is,  therefore,  though  palatable  and 
wholesome  for  drinking,  less  well  suited  for  washing,  cooking, 
and  manufacturing  purposes  than  the  softer  waters. 

To  guard  against  pollution,  the  surface  of  the  soil  around 
the  point  of  delivery  of  the  spring  should  be  walled  in,  and  the 
water  conducted  to  the  surface  by  a  short  pipe.  In  some  cases 
it  may  be  necessary  to  collect  the  water  issuing  from  a  spring, 
and  to  store  it  in  a  reservoir  before  distribution  to  the  houses 
of  the  consumers. 

The  yield  of  a  spring  may  be  estimated  by  observing  how  long 


WATER  23 

it  takes  to  fill  a  vessel  of  known  capacity.  It  is  well  to  know 
the  average  flow  throughout  the  year. 

In  chalk  and  sandstone  districts  springs  generally  occur  at 
points  much  below  the  level  of  the  surrounding  country,  as  these 
permeable'  rocks  themselves  form  vast  reservoirs.  In  the  oolite, 
owing  to  the  frequent  alternation  of  porous  and  retentive  strata, 
springs  are  common.  In  limestone  regions  main  springs  are  often 
fed  by  subterranean  reservoirs  caused  by  the  solution  of  the 
limestone  by  water  charged  with  CO.^.  The  most  constant  and 
abundant  springs  in  this  country  are  generally  in  the  chalk, 
oolite,  new  red  sandstone,  the  millstone  grits,  and  mountain 
limestones;  and  the  most  invariably  good  water  is  obtained 
from  the  lower  chalk  immediately  above  the  greensand. 

Springs  may  be  made  to  supply  water  to  houses  situated  above 
the  level  of  their  delivery  if  the  flow  is  sufficient  to  work  a  ram, 
turbine,  or  other  similar  form  of  pumping  engine,  so  that  the 
water  can  be  pumped  up  to  the  cistern  or  reservoir.  Sometimes 
the  spring  water  issuing  from  a  great  depth  is  warm  or  even 
hot.  This  is  due  to  the  fact  that,  below  the  level  at  which  varia- 
tions due  to  atmospheric  alternations  of  temperature  cease  to  be 
recognizable,  the  temperature  of  the  earth  increases  with  its 
depth,  and  the  water  temperature  rises  about  1°  F.  for  every 
50  to  60  feet  of  depth,  on  an  average. 

Wells. 

It  is  usually  said  that  there  are  thiee  kinds  of  wells,  shallow, 
deep,  and  artesian  ;  but  the  last  is  merely  a  variety  of  a  deep  well. 

Shallow  wells  are  those  which  are  sunk  into  superficial  porous 
beds  of  sand  or  gravel  overlying  an  impermeable  stratum  of  clay 
or  other  dense  rock.  They  tap  the  underground  water  held  up 
by  an  impermeable  stratum,  and  yield  a  water  identical  in 
composition  with  that  flowing  from  the  land  springs  in  the 
neighbourhood. "  The  depth  of  the  well  must,  of  course,  vary 
with  the  vertical  distance  of  the  impermeable  stratum  from  the 
surface  of  the  earth;  as  a  rule,  this  distance  is  not  great,  and, 
in  fact,  it  is  often  said  that  shallow  wells  are  those  which  are 
less  than  50  feet  deep;  but  it  is  better  to  keep  to  the  definition 
here  given. 

The  rural  population  of  this  country  derives  its  water  almost 
exclusively  from  shallow  wells.  Formerly  shallow  wells  were 
also  the  usual  sources  of  supply  in  towns;  but  these,  in  nearly 


24  HYGIENE   AND    PUBLIC   HEALTH 

all  instances,  have  now  been  abolished  in  favour  of  a  public 
supply  from  better  sources.  The  Rivers  Pollution  Commissioners 
(Sixth  Report)  stated  that  in  their  experience  shallow  wells  were 
almost  always  horribly  polluted  by  sewage  and  bj^  animal  matters 
of  the  most  disgusting  origin. 

Where  the  level  of  the  underground  water  is  but  a  few  feet 
from  the  surface,  it  is  obvious  that  the  surface  water,  which 
may  contain  impurities,  has  but  little  chance  of  being  purified 
in  its  passage  through  the  soil  to  the  well.  But  the  grosser 
pollutions  that  shallow  well  waters  suffer  from,  come,  not  from 
the  surface,  but  from  leaking  drains  and  cesspools  in  the  vicinity. 

Cesspools  are  but  rarely  made  watertight,  as  they  would 
then  require  to  be  frequently  emptied.  When  sunk  in  a  porous 
soil  and  merely  lined  with  bricks  without  mortar  or  cement, 
the  contents  soak  away,  and  the  cesspool  can  be  closed  over 
and  need  not  be  opened  for  many  years.  The  hquid  sewage 
percolates  through  the  soil  and  joins  the  underground  water 
below.  As  the  underground  water  is — as  before  explained — 
slowly  but  steadily  moving  along  in  the  direction  of  its  natural 
outlet,  the  position  of  the  well  in  regard  to  the  cesspool  is  all- 
important.  Should  the  well  be  above  the  cesspool,  the  under- 
ground water  flowing  from  the  well  to  the  cesspool,  the  risk  of 
pollution  is  greatly  diminished,  so  long  as  but  Httle  water  is 
drawn  from  the  well.  If  the  well  is  below  the  cesspool,  and  in 
the  line  of  flow  of  the  underground  water,  it  must  infallibly  be 
polluted  with  the  cesspool  soakage.  The  direction  of  flow  of  the 
underground  water  can  usually  be  determined  from  the  contour 
of  the  surrounding  country;  and  this  evidence  can  be  confirmed 
by  observations  on  the  height  of  the  underground  water  at 
different  places,  as  determined  by  the  height  of  the  water  above 
ordnance  datum  in  different  wells  or  trial  holes;  for  the  level 
of  the  underground  water  falls  as  it  approaches  its  outlet  in 
springs,  lakes,  streams,  or  rivers,  giving  rise  to  a  curve  which 
has  been  already  considered  {see  p.  21). 

When,  however,  the  amount  of  water  abstracted  is  sufficientl}^ 
great  to  cause  a  considerable  depression  of  the  water  in  the 
well,  the  well  then  drains  an  area  all  round  it  in  the  form  of  a 
circle;  and  in  such  a  case  it  would  not  matter  what  position 
the  well  had  to  the  cesspool  if  the  cesspool  was  included  within 
the  area  drained  by  the  well,  for  pollution  must  inevitably  occur. 
The   distance  within  which  a  well  draws  water  to  itself,  when 


WATER 


25 


its  own  water-level  has  been  depressed  by  pumping,  depends  on 
the  amount  of  the  depression  and  on  the  nature  of  the  soil. 

The  surface  of  the  underground  water  in  the  area  of  the  circle 
drained  by  a  well  depressed  by  pumping  has  the  form  of  a  cur- 
vilinear cone,  with  steep  gradient  near  the  well,  but  becoming 
more  nearly  horizontal  as  the  distance  from  the  well  increases 

(fig-  2). 

We  have  thus  seen  that  the  conditions  which  favour  the  con- 
tamination of  a  shallow  well  from  cesspools  or  other  forms  of 
pollution  are:  (i)  Its  position  as  to  cesspools  or  other  sources 
of  pollution,  with  regard  to  the  flow  of  underground  water; 
(2)  the  amount  of  depression  of  water-level  in  the  well  which 
may  be  produced  at  any  time  by  pumping;  (3)  the  nature  of 
the  soil  in  which  the  well  is  sunk,  as  regards  porosity  and  the 

B 


Fig.  2. — Depression  of  Water  in  Shallow  Well  by  Pumping. 
A ,  well ;  B,  cesspool ;  C,  underground  water  cvurve.      (After  Field  and  Peggs.) 

easy  passage  of  water.  It  is  quite  possible,  if  these  conditions 
are  attended  to,  to  sink  a  well  that  shall  be  uncontaminable 
in  or  near  a  village,  in  which  the  shallow  wells  are  generally 
polluted  with  cesspool  soakage. 

The  well  must  be  sunk  in  such  a  position  as  regards  possible 
sources  of  pollution  that  the  undergound  water  flows  from  the 
well  to  the  sources  of  pollution.  The  distance  of  the  well  from 
such  possible  polluting  sources  should  be  from  100  to  160  times 
the  depression  of  the  water  in  the  well  that  is  ever  likely  to  be 
produced  by  pumping,  this  distance  varying  with  the  nature 
of  the  soil.  The  mouth  of  the  well  should  be  closed  over, 
and  the  water  raised  by  an  iron  pump;  draw  wells,  where 
the  water  is  raised  by  a  windlass,  chain,  and  bucket  through 
an   open   mouth,   are  liable  to  accidental   contamination   from 


26  HYGIENE   AND   PUBLIC    HEALTH 

refuse  being  thrown  in,  or  animals  falling  in.  To  prevent 
contamination  from  impure  surface  washings,  the  mouth  of  the 
well  should  be  protected  by  a  coping  carried  up  to  about  a  foot 
above  the  surface  of  the  ground,  and  the  drainage  water  from 
the  pump  should  be  conducted  away  to  a  safe  distance. 

It  is  very  desirable  to  make  the  walls  of  a  shallow  well  im- 
pervious. When  the  porous  stratum  in  which  the  well  is  sunk 
is  of  considerable  depth,  the  sides  of  the  well  for  about  20  feet 
should  be  imperviously  steined  with  brickwork  set  in  and 
lined  with  hydraulic  cement;  or  cast  or  wrought  iron  cylinders 
may  be  employed  for  Hning  the  upper  portion.  If  this  is  done, 
water  percolating  from  the  surface  must  pass  through  about 
20  feet  of  soil  before  entering  the  well,  and,  in  its  passage  through 
the  soil,  the  organic  impurities  in  the  water  will  be,  to  a  certain 
extent,  removed.  The  less  the  fluctuation  in  level  of  the  subsoil 
water,  the  more  likely  is  the  supply  to  be  permanent,  and  the  less 
the  liability  to  contamination. 

It  is  a  noteworthy  circumstance  in  regard  to  the  grossly 
polluted  waters  of  many  shallow  wells,  that  they  are,  as  a  rule, 
clear,  sparkling,  and  very  palatable.  The  organic  filth  from 
cesspools  and  drains,  in  its  passage  through  even  a  few  feet 
of  porous  soil,  is  filtered  and  deprived  of  suspended  matters, 
but  does  not  lose  its  dangerous  properties.  The  shallow  well 
into  which  the  filth  percolates  is  found  to  furnish  a  water  loaded 
with  ammonia  and  chlorides — evidences  of  sewage  (urine)  con- 
tamination— with  organic  matter  in  solution,  and  with  nitrates 
and  nitrites,  the  oxidized  residues  of  organic  matters  ;  but  yet, 
from  its  containing  abundance  of  carbonic  acid  gas,  the  water 
is  sparkling  and  palatable.  Such  wells,  however,  after  a 
heavy  rainfall,  are  sometimes  liable  to  furnish  a  turbid  and 
foul-smelling  water  which  nobody  would  think  of  drinking. 
The  heavy  rain  washes  foul  substances  in  the  soil,  derived  bj^ 
soakage  from  manure-heaps,  middens,  privies,  leaky  drains,  or 
cesspools,  direct  into  the  well,  no  time  being  allowed  for  that 
filtering  and  partial  purification  which  does  so  much  to  give  the 
well  water  at  ordinary  times  its  pure  and  deceptive  appearance. 

Where  suspicion  is  entertained  that  a  well  water  is  polluted, 
the  method  by  which  the  polluting  material  reaches  the  well 
may  sometimes  be  ascertained  by  the  use  of  solutions,  which 
either  by  reason  of  their  colour,  taste,  or  chemical  properties, 
can  be  easily  identified,  even  when  largely  diluted.     For  this 


WATER  27 

purpose  strong  solutions  of  common  salt,  lithia  salts,  an  alkaline 
solution  of  fluorescein,  paraffin  oil,  or  an  emulsion  of  Bacillus 
prodigiosus  have  been  employed.  When  introduced  into  the 
drain,  cesspool,  or  other  supposed  source  of  the  mischief,  such 
solutions  will  within  a  few  days,  if  the  supposition  is  correct,  be 
found  in  the  well  water.  For  most  purposes  fluorescein,  along  . 
with  a  similar  quantity  of  sodic  hydrate,  is  preferable  to  the  other 
substances,  as  it  is  very  soluble,  has  great  colorific  power,  is 
easily  identified,  and  is  harmless  in  small  traces.  One  grain 
imparts  a  visible  green  fluorescence  to  over  500  gallons  of  water. 
Emulsions  of  Bacillits  prodigiosus  are  of  use  where  leakage  into 
a  well  from  the  surrounding  soil  is  suspected,  and  it  is  desired 
to  ascertain  if  the  filtering  power  of  the  soil  is  sufficient  to 
arrest  the  passage  of  bacterial  organisms  contained  in  sewage 
or  other  polluting  liquids. 

In  making  an  examination  of  a  well,  the  cover  should  be 
taken  off,  and  the  sides  of  the  well  should  be  carefull}^  examined 
for  evidence  of  liquids  finding  their  way  through  the  brickwork, 
or  for  the  discoloration  of  the  sides  due  to  past  leakages.  The 
position  of  the  pump  and  the  rising  main  should  be  noted,  and 
the  point  at  which  the  latter  leaves  the  well  should  be  examined. 
The  depth  of  the  water  in  the  well,  the  distance  of  the  water-level 
from  the  ground  surface,  and  the  depression  of  water-level 
caused  by  pumping  should  be  ascertained,  also  the  time  that 
elapses  before  the  original  water-level  is  restored  after  pumping 
ceases.  The  surroundings  of  the  well  should  be  noted,  the 
distances  from  possible  sources  of  pollution,  and  the  porous  or 
impervious  nature  of  the  soil  and  subsoil.  The  condition  of 
the  ground  around  the  well,  and  the  method  of  disposal  of  the 
waste  water  from  the  pump  should  also  receive  attention.  If 
samples  of  the  water  are  taken,  it  is  often  desirable  that  a  sample 
should  be  taken  from  near  the  surface  of  the  water,  as  well 
as  from  near  the  bottom,  as  polluting  materials  may  be  very  un- 
equally distributed  in  stagnant  water,  undisturbed  by  any  currents. 

Polluted  shallow  well  waters  are  usually  hard,  and  therefore 
unsuited  for  domestic  purposes.  The  hardness  is  sometimes 
due  to  the  polluting  liquids  which  find  their  way  into  the  well, 
but  httle  being  caused  by  the  mineral  salts  present  in  the  strata 
through  which  the  well  is  sunk.  Another  source  of  pollution  of 
shallow  wells  is  the  vicinity  of  gravej^ards,  especially  when  the 
subsoil  water  is  liable  to  rise  up  to  the  level  of  the  coffins. 


28  HYGIENE  AND  PUBLIC  HEALTH 

Tube  wells  are  contrivances  for  obtaining  water  from  super- 
ficial porous  strata  by  means  of  borings.  They  were  largely 
used  during  the  Abyssinian  campaign,  where  the  occupation 
of  any  piece  of  ground  was  necessarily  temporary,  the  tube 
being  quickly  sunk  and  as  quickly  withdrawn.  An  iron  tube 
.  with  a  steel  nozzle  and  perforations  at  its  lower  end  for  the 
passage  of  water  is  driven  into  the  ground  by  a  driving  weight 
or  "monkey";  before  it  has  altogether  disappeared  into  the 
ground  another  length  of  tube  is  screwed  on,  and  this  is  then 
driven  in.  Successive  lengths  of  tube  are  attached  until  a  depth 
of  20  to  28  feet  is  reached,  when  a  hand  -  pump  is  screwed 
on  the  top  and  the  water  pumped  out.  Difficulty  is  often 
experienced  from  sand  blocking  the  lower  part  of  the  tube  and 
the  perforations.  The  sand  must  be  dislodged  by  a  clearing 
tool,  or  pumped  out  until  a  space  free  from  sand  is  formed 
around  the  nozzle,  and  the  water  issues  clear  and  bright.  These 
tube  wells  are  most  suitable  where  the  distance  of  the  water 
from  the  surface  of  the  ground  is  not  more  than  a  few  feet,  and 
it  is  sometimes  advantageous  to  drive  one  from  the  bottom 
of  an  ordinary  well  to  increase  its  yield.  They  can  be  used  in 
gravel,  coarse  sand,  or  chalk,  but  their  use  in  clay  soils,  marls, 
or  fine  sand  is  not  satisfactory. 

Deep  wells  are  those  which  are  sunk  to  considerable  depths 
in  search  of  water  through  regular  geological  strata  such  as 
chalk,  oohte,  and  sandstone.  Those  also  are  known  as  deep 
wells  which  pass  through  a  superficial  porous  bed  and  an  under- 
lying impermeable  stratum  to  reach  water-bearing  strata  below, 
though  often  at  no  great  distance  from  the  surface.  In  sinking 
a  deep  well,  as  soon  as  the  water-bearing  strata  are  reached  the 
water  often  rises  rapidly,  and  may  even  overflow  at  the  surface. 

If  the  sides  of  a  deep  well  of  this  nature  are  properly  steined 
with  brickwork  set  in  cement  as  far  down  as  the  impermeable 
stratum,  surface  waters  and  underground  water  resting  on  this 
stratum  are  entirely  excluded,  and  the  v  ell  is  freed  from  those 
sources  of  pollution  which  so  often  contaminate  shallow-well 
waters.  In  hard  chalk,  new  red  sandstone,  oolite,  and  hmestone, 
the  wells  require  no  lining,  but  in  clays,  marls,  and  in  all  free 
and  broken  strata  they  should  be  steined. 

The  water  collected  from  deep  wells  has  usually  travelled  a 
long  distance  since  it  fell  as  rain  on  the  surface  of  the  earth; 
for  the  outcrop  of  the  water-bearing  strata  on  the  surface,  which 


WATER 


29 


are  the  catchment  areas  for  the  rain,  may  be  many  miles  from 
the  spot  at  which  the  well  is  sunk,  as  is  the  case  with  the  deep 
wells  in  the  chalk  sunk  into  the  London  basin. 

The  London  basin  is  interesting  as  an  example  of  a  geological 
formation  with  water-bearing  strata  in  different  rocks  at  varying 
depths  from  the  earth's  surface     ^  "  "" 

(fig.  3).  Most  superficially  are  the 
subterranean  waters  in  the  beds 
of  gravel  or  alluvium  of  but  slight 
thickness  (10  to  30  feet)  upheld 
by  the  London  clay.  These 
waters  supplied  the  shallow  wells 
which  formerly  formed  so  large 
a  part  of  the  water  supply  of 
London.  After  boring  through 
the  London  clay  (100  to  400 
feet  in  the  neighbourhood  of 
London)  water  is  again  reached 
— or  was  before  these  strata 
were  exhausted — in  the  Lower 
London  Tertianes,  beds  of  sand, 
gravel,  and  clay  of  variable 
thickness  (20  to  100  feet),  with 
limited  outcrops  beyond  the 
edge  of  the  London  clay,  and 
more  or  less  surrounding  it  as 
they  rise  from  the  margin  of  the 
basin.  Having  such  a  limited 
outcrop  exposed  to  rainfall,  the 
water  which  accumulated  in  the 
deep  strata  of  these  beds  under 
the  London  clay  was  soon  ex- 
hausted, when  numerous  wells 
were  sunk  into  them. 

Beneath  the  Lower  London 
Tertiaries  comes  the  chalk,  with 
its  outcrop  in  the  chalk  hills  and  downs,  north,  south,  and  west 
of  the  Thames  basin  and  many  miles  from  its  centre.  The  outcrop 
forms  a  very  extensive  catchment  area  for  rain,  which,  perco- 
lating through  the  joints  and  fissures  of  the  chalk,  gives  rise 

to   vast  reservoirs  of  subterranean  water  in  the   underground 


30  HYGIENE    AND    PUBLIC   HEALTH 

extension  of  this  rock  beneath  the  tertiary  beds  of  the  London 
basin.  As  the  London  basin  is  hohowed  into  the  form  of  a 
shallow  trough,  the  sides  of  the  trough  being  the  outcrop  of  the 
chalk  in  hills  and  downs,  it  follows  that  the  water  in  the  chalk 
is  also  trough-shaped,  and  that  when  wells  or  borings  are  sunk 
into  it  near  the  centre  of  the  London  basin,  the  water  tends  to 
rise  in  the  boring,  and  may  even  overflow  at  the  surface,  forming 
true  Artesian  wells.  In  consequence  of  the  number  of  borings 
drawing  water  from  the  chalk  near  London,  the  water-level  has 
been  lowered;  and  borings  have  now  to  be  made  deeper  than 
formerly.  Owing  to  the  joints  and  fissures  in  the  chalk  allowing 
a  free  passage  for  water,  the  distance  which  a  well  or  boring 
drains,  when  its  water-level  is  depressed  by  pumping,  is  very 
great;  and  thus  borings  at  considerable  distances  from  one 
another  are  mutually  affected  by  continued  pumping  in  any  one 
of  them.  If  a  boring  in  the  chalk  should  not  happen  to  open  up 
any  fissures  or  cracks,  it  may  supply  but  a  limited  quantity  of 
water,  or  none  at  all. 

Beneath  the  chalk  is  the  upper  greensand  in  thin  beds  (lo  to 
30  feet),  with  a  very  limited  outcrop  around  the  edge  of  the 
chalk;  and  beneath  this  again  is  the  gault,  a  bluish  clay  with 
an  average  thickness  of  130  to  200  feet.  Under  the  gault  lies 
the  lower  greensand  in  very  thin  beds,  often  completely  thinned 
out,  and  therefore  absent.  Although  the  greensands  are  rocks 
permeable  to  water,  neither  the  upper  nor  lower  beds  have  yielded 
water  in  any  quantity  to  deep  borings  in  the  neighbourhood  of 
London.  Their  outcrop  is  very  limited,  with  but  a  small  ex- 
posure of  catchment  area  for  rain ;  and  these  formations  appear 
also  to  thin  out  considerably  in  their  underground  extensions 
towards  the  centre  of  the  basin.  Near  their  outcrops  in  many 
places  the  greensands  furnish  abundant  supplies  of  water,  which 
are,  however,  very  frequently  due  to  percolation  from  the  over- 
lying chalk. 

Several  borings  made  in  or  near  London  have  passed  through 
all  the  strata  above  mentioned  into  the  primary  rocks  beneath. 
In  making  these  borings  it  is  usual  to  excavate  a  wide  well-hole 
for  some  depth,  from  the  bottom  of  which  a  bore  tube  of  small 
diameter  (6  to  15  inches)  is  sunk.  The  water  should  rise  through 
the  bore  tube  in  sufficient  volume  to  form  a  reservoir  in  the 
lower  part  of  the  well-hole,  from  which  it  can  be  pimiped  to  the 
surface  from  considerable  depths.    Boring  tools  of  large  diameter 


WATER  31 

have  been  recently  introduced,  and  these  are  found  less  costly, 
whilst  the  borings  are  more  easily  made.  At  some  new  works 
in  the  chalk  at  Southampton,  the  bore  tubes  are  6  feet  in 
diameter.  It  has  been  in  many  cases  found  that  the  driving 
of  headings  ("  galleries  ")  and  adits  horizontally  below  the  water- 
level  is  more  effective  in  increasing  the  yield  of  wells  than 
deepening  them,  as  the  area  of  collection  of  water  is  thereby 
increased,  and  there  is  a  greater  likelihood  of  striking  the  fissures 
through  which  the  largest  volumes  of  water  are  moving. 

Artesian  wells,  so  called  from  the  province  of  Artois  in  France, 
where  they  have  long  been  in  use,  are  formed  when  a  boring 
taps  a  subterranean  reservoir  confined  in  a  permeable  stratum 
by  impermeable  strata  above  and  below,  the  permeable  stratum 
having  its  outcrops  on  the  surface  at  considerably  higher  levels 
than  the  surface  of  the  ground  where  the  boring  is  sunk.  The 
subterranean  reservoir  is  consequently  basin-shaped;  and  the 
water,  when  tapped  at  the  lower  part  of  the  basin,  strives  to 
regain  its  level  by  flowing  up  the  boring  and  spouting  out  at  its 
mouth.  The  waters  which  feed  these  wells  often  come  from  a 
great  distance,  the  outcrops  of  the  permeable  strata  on  each  side 
of  the  basin  being  sometimes  60  or  70  miles  from  the  well  in 
a  straight  line.  The  best  Artesian  wells  are  found  in  the 
chalk. 

The  water  supplied  by  deep  wells  is  generally  remarkably 
free  from  organic  impurities,  even  when  sunk  in  the  midst  of 
large  cities.  Nitrogen,  as  nitrates  and  nitrites,  is  usually  present 
in  deep  well  waters;  the  other  mineral  constituents  of  the  well 
water  depend  chiefly  on  the  strata  through  which  the  water  has 
percolated,  and  on  the  solubility  of  the  component  elements  of 
these  strata  by  water  charged  with  carbonic  acid. 

In  the  near  neighbourhood  of  the  sea  there  is  a  danger  of  the 
infiltration  of  sea  water  into  deep  wells,  especially  when  sunk  in 
chalk  formations.  Such  infiltration  is  recognized  by  an  increase 
in  the  amount  of  chlorine  in  the  well  water,  and  is  probably  due 
in  some  cases  to  excessive  pumping  causing  considerable  depres- 
sion in  the  water-level  of  the  well.  It  has  happened  that  the 
brackishness  so  caused  has  rendered  a  town  water  supply  quite 
unusable  for  domestic  purposes,  and  has  given  rise  to  diarrhoea 
and  other  evidence  of  gastro-intestinal  disturbance  among  some 
of  those  drinking  it. 

The  yield  of  water  from  a  well  can  only  be  ascertained  by 


32 


HYGIENE    AND   PUBLIC   HEALTH 


De6[^  Well 

Shallow  Weill 

Artesian  Well 


pumping  down  to  a  certain  level,  and  observing  the  length  of 
time  required  for  the  water  to  regain  its  original  level.  In  this 
country  the  largest  supplies  of  deep  well  water  are  obtained 
from  the  chalk,  the  oolite,  and  the  new  red  sandstone. 


WATER  33 

Although  deep  wells,  when  protected  from  surface  drainage  in 
their  upper  parts,  are  but  rarely  polluted,  even  when  situated 
in  the  centre  of  towns,  it  does  occasionally  happen  that  liquid 
soakage  from  sewers  or  cesspools  finds  its  way  into  fissures^  in 
chalk  or  sandstone,  which  conduct  it  to  the  water  of  the  well, 
unfiltered  and  therefore  unpurified,  and  pregnant  with  danger  to 
the  consumers.  Deep  wells  in  Liverpool  and  other  places  have 
been  closed  for  this  reason. 

Systematic  investigations  in  order  to  gauge  the  extent  of  the 
pollution  of  village  water  supplies  are  desirable;  indeed,  they 
are  demanded  under  the  provisions  of  the  Public  Health  (Water) 
Act,  1878.  In  some  cases,  where  these  have  been  made,  practi- 
cally every  well  water  in  a  village  has  been  shown  to  be  danger- 
ously contaminated. 

When  it  happens  that  villages  are  sufficiently  convenient  to 
an  existing  water  main  which  is  taking  water  to  some  larger 
community,  a  public  supply  may  sometimes  be  obtained  from 
that  source  at  a  reasonable  cost.  Then,  again,  where  larger 
villages  cluster  conveniently,  a  combined  water  supply  may  be 
provided  at  a  less  cost  than  a  separate  supply  to  each  village 
would  incur. 

The  provision  of  a  public  village  supply  may  be  made  as  cheap 
as  possible  by  simply  carrying  a  main  from  the  storage  reservoir 
through  the  village,  and  providing  a  few  pillar  taps  in  selected 
positions.  To  meet  the  special  circumstances  of  the  smaller 
villages  scattered  at  considerable  distances  from  each  other, 
the  existing  polluted  wells  should  be  closed,  and,  where 
practicable,  one  or  more  deep  wells,  or  even  one  or  more 
new  shallow  wells  (where  the  yield  is  satisfactory)  specially 
constructed,  (concrete  tubes  are  cheap  and  satisfactory),  and 
placed  in  selected  positions,  should  be  provided  for  the  use  of 
the  villagers. 

The  following  facts  will  be  found  of  value  in  seeking  for  water. 
In  comparatively  flat  districts,  trials  should  be  made  by  Norton's 
tube  wells  at  the  lowest  sites  on  the  survey.  The  part  most 
covered  by  herbage  is  probably  the  site  where  the  water  reaches 
nearest  to  the  surface.  The  same  fact  is  sometimes  denoted  by 
localized  early  morning  mists  or  swarms  of  insects.    The  nearer 

'  Faults,  fissiires,  joints  or  dislocations,  are  defects  which  are  due  to 
the  excessive  strain  of  contraction  when  drying  or  to  movements  of  the 
earth's  crust. 

3 


34  HYGIENE    AND    PUBLIC   HEALTH 

the  sea,  the  more  likely  is  water  to  be  found,  but  if  too  near  the 
sea  the  water  may  be  brackish. 

In  hilly  country  a  search  should  be  made  in  the  deepest  valleys, 
especially  the  side  of  the  valley  towards  the  highest  hill,  and  at 
the  junction  of  two  long  valleys.  If  there  is  any  evidence  of 
an  original  watercourse  at  this  point,  water  is  often  found  at  no 
great  depth.  A  knowledge  of  the  dip-^  of  the  strata  in  the 
district,  and  the  situation  and  area  of  their  outcrop,  is  of  the 
greatest  value  in  such  an  investigation. 

Pumps. 

Suction  Pump. — Fig.  5  shows  a  section  of  a  common  suction  pump, 
which  works  by  the  exhaustion  of  air  inside  a  cyhnder,  by  means  of  the 
upward  stroke  of  a  piston ;  the  atmospheric  pressure  on  the  surface  of  the 
water  forcing  the  water  up  through  the  suction  pipe  into  the  cylinder. 
The  downward  stroke  of  the  piston  forces  the  water  through  the  piston 
valve,  and  the  next  upward  stroke  delivers  it  through  the  spout  of  the 
pump.  Where  water  has  to  be  delivered  at  a  height  above  the  pump,  the 
spout  is  replaced  by  a  pipe  (the  rising  main)  with  a  valve  at  the  point  of 
attachment  to  the  cylinder,  which  permits  water  to  enter  the  rising  main, 
but  prevents  its  reflux  into  the  cylinder.  In  this  class  of  pump  the  lift 
of  water  is  effected  by  the  upward  stroke  of  the  piston,  and  the  delivery 
is  in  consequence  intermittent.  At  each  up-stroke  of  the  piston  the  suction 
or  clack  valve  C  is  opened  and  the  piston  valve  B  is  closed ;  at  each 
down-stroke  the  action  of  the  valves  is  reversed.  The  height  of  the  clack 
valve  C  above  the  lowest  level  of  the  water  to  be  raised  must  not  be  more 
than  25  feet.  Although  theoretically  atmospheric  pressure  is  capable  of 
supporting  a  column  of  water  33'9  feet  in  height,  practically  the  most 
perfect  vacuum  obtainable  in  a  suction  pump  is  only  equivalent  to  25  feet 
of  head,  and  these  pumps  work  best  with  heights  of  less  than  1 5  feet. 

Force  Pumps. — Sections  of  force  pumps  are  shown  in  figs.  6-7.  These 
pumps  are  used  where  water  has  to  be  raised  to  a  height  exceeding  25  feet, 
as  from  deep  wells.  In  each  case  the  water  is  raised  by  suction  into  the 
pump,  but  whilst  in  the  single  acting  pump  (fig.  6)  the  delivery  is  inter- 
mittent, in  the  double-acting  pump  (fig.  7)  the  flow  of  water  is  continuous. 

Semi-rotary  Pumps. — These  are  suction  and  lift  pumps,  in  which  the 
water  is  raised  by  the  suction  induced  in  a  small  disc-shaped  cylinder  by 
means  of  metal  valves  rotating  in  a  half-circle  at  a  considerable  speed. 
These  pumps  are  small,  occupy  little  space,  and  are  easily  worked  bj'  a 
lever  with  vertical  action. 

Centrifugal  Pumps. — These  are  used  (see  fig.  8)  where  large  quantities 
of  water  or  sewage  have  to  be  raised  through  a  moderate  lift,  not  exceeding 
25  feet.  The  apparatus  is  simple  and  compact,  consisting  of  revolving 
fans,  which  by  their  rapid  revolution  cause  a  vacuum,  and  draw  water 
through  a  suction  pipe  into  the  centre  of  the  rotary  wheel.  The  centri- 
fugal action  set  up  by  the  fans  causes  the  water  to  be  ejected  through  the 
dcliverv  pipe.  The  wheel  is  made  to  revolve  by  belting  passing  round 
the  fly-wheel  of  a  steam,  gas,  or  oil  engine. 

1  The  term  "  dip  "  refers  to  the  inclination  of  the  strata  to  the  horizon  : 
an  originally  horizontal  deposit  dips  from  movements  of  the  earth's  crust. 
A  "  strike  "  is  a  line  drawn  at  right  angles  to  the  direction  of  the  dip. 


WATI-R 


35 


--^ 


Fig.  S- — Suction  Pump. 

A,  piston ;  B,  piston  valve ; 
C,  suction  or  clack 
valve;  D,  suction  pipe; 
E,  water;  F,  spout. 


Fig.    6.  —  Single  -  Acting 
Suction  and  Force  Pump. 

V,  V>,  valves. 


Fig.  7.  —  DouBLE- 
Acting  Suction 
AND  Force  Pump.     M 

V,  VI,  V2,  V3,  valves. 


Fig.  8. — Centrifugal 
Pump. 


36 


HYGIENE    AND    PUBLIC   HEALTH 


Chain  Pumps. — In  this  pump,  water  is  raised  by  means  of  a  series  of  small 
buckets  attached  at  equal  distances  to  an  endless  chain,  which  passes  round 
a  vertical  wheel  above  and  dips  into  the  water  below.  Instead  of  the 
buckets,  the  endless  chain  may  be  enclosed  in  a  tube,  and  carry  a  number 
of  equidistant  diaphragms  provided  with  leather  washers  just  large  enough 
to  work  up  and  down  inside  the  tube.  The  vertical  wheel  is  made  to  revolve, 
and  the  little  buckets,  or  the  diaphragms,  in  their  ascent  lift  the  water,  and 
discharge  it  into  a  spout  at  the  top  of  the  apparatus.  These  pumps  are 
especially  suitable  for  raising  sewage  or  other  water  containing  suspended 
matter,  which  is  apt  to  clog  and  derange  the  action  of  ordinary  pump 
valves. 

Pulsometers. — These  are  mostly  used  for  temporary  pumping  purposes. 
The  pump  consists  of  two  vessels  with  a  ball  valve  at  the  top,  steam  from  a 
boiler  being  admitted  alternately  into  each  vessel.  The  steam  forces  the 
water  out  of  the  vessel  into  the  rising  main  or  delivery  pipe ;  and  the 
condensation  of  the  steam,  by  contact  with  the  cold  sides  of  the  vessel, 
causes  a  vacuum,  the  pump  thus  having  a  suction  effect  on  the  water  over 
which  it  is  suspended,  which  rises  through  a  suction  tube  and  suction 
valve  into  the  pulsometer.  Thus  alternate  condensation  and  discharge 
takes  place  in  each  of  the  two  vessels  composing  the  pulsometer,  and  there 
is  a  continuous  discharge  of  water  so  long  as  steam  is  supplied. 

Water-wheels. — By  the  use  of  water-wheels  the  motive  power  of  a  running 
stream  can  be  utilized  in  raising  water  to  a  height.  Vertical  water-wheels 
are  of  three  kinds:  (i)  Overshot,  when  the  water  is  delivered  on  the  top  of 
the  wheel ;  (2)  Breast,  when  the  water  is  delivered  near  the  centre  of  the 
wheel ;  and  (3)  Undershot,  when  the  wheel  is  driven  from  the  bottom  by 
the  impact  of  a  strong  current.  For  overshot  and  breast  wheels  the 
stream  must  be  dammed,  as  seen  in  the  common  mill  dam  and  wheel.  By 
suitable  gearing  the  circular  motion  of  the  wheel  is  transformed  into  the 
reciprocating  motion  of  the  piston  rod  of  the  pump  used  to  lift  the  water 
of  the  well  or  reservoir. 

Hydraulic  Ram. — When  water  flowing  rapidly  in  a  pipe  is  suddenly 
checked,  there  is  an  increase  of  pressure  on  the  interior  of  the  pipe.  This 
increase  of  pressure  is  known  as  ramming,  and  is  used  to  force  a  certain 
proportion  of  the  water  flowing  down  the  pipe  to  a  height  above  the  point 
at  which  ramming  takes  place.  The  apparatus  is  shown  diagrammatically 
in  fig.  9.      Water   descends  with  considerable  velocity  down  the  supply 


Fig.  9. — Hydraulic  Ram. 

V,  self-acting  pulsating  discharge  valve;  A,  air  vessel;  O,  ball  valve; 
S,  supply  pipe;  E,  delivery  pipe. 


pipe  S  from  a  stream  or  reservoir,  and  runs  to  waste  through  an  opening 
at  V,  which  is  guarded  by  a  valve.  But  the  momentum  of  the  water  in  its 
flow  is  sufficient  to  overcome  the  weight  of  the  valve,  which  is  raised  and 
closes  the  orifice.  The  flow  of  water  thus  momentarily  checked  causes 
an  increase  of  internal  pressure  in  the  apparatus,  and  the  ball  valve  O 
is  opened,  allowing  water  to  pass  into  the  air-chamber  A,  where  the  cushion 


WATER  37 

of  compressed  air  drives  the  water  steadily  up  the  pipe  IL  to  the  storage 
tank.  As  soon  as  the  pressure  is  reduced  by  the  opening  of  the  ball  valve  O 
the  discharge  valve  falls,  and  water  again  escapes  at  V,  until  the  velocity 
of  flow  reaches  the  point  at  which  the  discharge  valve  is  again  raised,  and 
the  cycle  oi  events  is  reproduced.  A  fall  of  lu  feet  from  a  stream  or 
reservoir  to  the  ram  is  sufficient  to  raise  water  to  a  height  150  feet  above 
the  ram. 

Composition  of  Water  from  Various  Sources. 

The  nature  and  amount  of  the  organic  pollution  to  which 
water  from  various  sources  is  liable,  is  such  a  variable  quantity 
that  it  is  useless  and  misleading  to  attempt  any  classification 
under  this  head ;  for  it  is  local  circumstances  that  will  determine 
whether  a  shallow  well  water  is  polluted  or  a  deep  well  water 
is  pure.  Generally  speaking,  however,  the  purest  waters  are 
derived  from  deep  springs  and  wells  and  upland  surfaces,  while 
the  waters  from  the  subsoil,  from  cultivated  surfaces,  and  from 
rivers  are  especially  liable  to  be  organically  polluted.  But  the 
character  of  the  soil  and  subsoil  from  which  the  water  is  collected 
influences  its  composition  to  an  extent  which,  though  variable, 
may  be  approximately  defined  by  chemical  analysis. 

I.  Surface  Waters. — Those  waters  collected  from  the  hard  sur- 
faces of  the  practically  impervious  rocks  which  support  little 
animal  or  vegetable  life  are  very  pure.  They  commonly  contain 
less  than  10  parts  of  total  solids,  5  of  total  hardness,  i  of  chlorine, 
and  o-i  of  nitrogen  as  nitrates,  in  100,000  parts  of  water.  The 
mineral  solids  consist  mainly  of  sodium  carbonate  and  chloride, 
and  a  trace  of  lime  or  magnesia.  The  variable  amount  of  organic 
matter,  which  is  often  exclusively  of  vegetable  origin  (peat),  yields 
practically  no  free  ammonia;  but  the  organic  ammonia  figure 
and  that  of  the  oxygen  absorbed  by  organic  matter  may  be  high, 
in  which  case  the  water  is  often  highly-coloured  and  acid  in 
reaction.  Such  characters  are  presented  by  the  waters  collected 
from  the  surfaces  of  the  igneous  metamorphic  (quartz,  mica, 
granite,  etc.),  Cambrian,  Silurian,  and  Devonian  rocks. 

The  waters  from  the  surface  of  the  non-calcareous  carboniferous 
rocks  (Yoredale  rocks,  millstone  grits,  and  coal  measures)  are 
very  similar;  but  those  which  have  flowed  over  the  surface  of 
the  calcareous  carboniferous  rocks  —  the  mountain  limestone 
and  limestone  shales — differ  from  the  former  in  possessing  a 
moderate  degree  of  hardness,  higher  total  solids,  and  a  neutral 
or  faintly  alkaline  reaction.  The  mineral,  solids  consist  chiefly 
of  sulphate  and  carbonate  of  calcium  and  magnesium. 


38  HYGIENE    AND   PUBLIC   HEALTH 

Surface  waters  from  the  lias,  new  red  sandstone,  magnesian 
limestone,  and  oolite  may  vary  considerably  in  their  composition. 
The  total  solids  are  generally  between  lo  and  20  parts  per  100,000, 
the  total  hardness  between  10  and  15  parts,  the  chlorine  is  below 
2  parts  per  100,000,  and  the  nitrogen  as  nitrates  below  0-2  of  a 
part. 

Clay  waters  are,  as  a  rule,  opaque,  from  a  variable  quantity 
of  suspended  matter,  but  generally  there  are  few  dissolved 
solids,  and  the  water  is  fairly  soft.  They  vary,  however,  greatly 
in  their  composition.  The  waters  collected  from  cultivated  land 
present  great  variations  in  composition,  and  the  total  hardness 
may  range  from  5  to  20  parts  per  100,000,  according  as  to 
whether  the  soil  is  non-calcareous  or  calcareous.  Alluvium 
is  generally  a  mixture  of  sand,  clay,  and  organic  matter;  and 
waters  from  such  a  source  generally  contain  high  mineral  solids 
(50  to  100  parts),  consisting  of  calcium  and  magnesium  salts, 
sodium  chloride,  iron,  and  silica,  and  also  excess  of  organic 
matters. 

2.  Waters  from  a  Depth. — Those  collected  from  the  chalk 
are  generally  clear,  bright,  and  well  charged  with  carbonic  acid. 
The  total  solids  are  generally  from  25  to  50  parts  per  100,000, 
and  the  total  hardness  from  15  to  30  parts;  the  hardness  is 
mostly  temporary,  and  calcium  carbonate  may  vary  from  10  to 
30  parts.  The  chlorine  is  commonly  from  2  to  3  parts,  but  it 
may  reach  a  higher  figure  in  some  pure  chalk  waters.  The 
nitrogen  as  nitrates  is  below  0-5  part  per  100,000,  and  is  com- 
monly about  0-3.  Sulphates  are  present  in  small  quantity,  and 
there  is  often  a  trace  of  phosphates  and  of  iron.  Although  the 
carbonic  acid  present  is  often  sufficient  to  turn  blue  litmus  red, 
when  this  is  driven  off  an  alkaline  reaction  is  invariably  obtained. 

Some  waters  derived  from  the  chalk  are  very  soft  and  contain 
sodium  carbonate.  They  are  only  found  where  the  chalk  lies 
buried  beneath  a  thick  mass  of  London  clay  (Thresh). 

Waters  from  the  oolite  present  characters  very  similar  to  those 
from  the  chalk. 

Those  derived  from  limestone  and  magnesian  limestone 
formations  only  differ  from  the  chalk  waters  in  generally  con- 
taining more  total  solids,  far  more  calcium  or  magnesium  sulphate 
(which  may  reach  nearly  20  parts  per  100,000),  and  less  calcium 
or  magnesium  carbonate,  and  by  consequence  the  hardness  is 
generally  higher  and  to  a  greater  degree  permanent. 


WATER  39 

In  dolomite  districts  the  mineral  solids  contain  much  mag- 
nesium carbonate  and  sulphate,  and  a  large  proportion  of  the 
total  hardness  is  permanent,  dolomite  being  a  double  carbonate 
of  lime  and  magnesia. 

The  greensands  are  porous  strata  containing  a  reducing  salt 
of  iron,  which  by  reducing  oxidized  nitrogen  to  ammonia  often 
furnishes  to  the  water  a  very  high  figure  of  free  ammonia.  The 
total  solids  vary  considerably,  but  they  sometimes  approach 
100  parts  per  100,000  where  the  water  is  collected  at  great 
depths  from  greensand  underlying  the  chalk;  the  chlorine  may 
reach  a  figure  of  from  4  to  14  parts ;  the  total  hardness  (much  of 
which  is  permanent)  is  very  variable — from  a  low  to  a  high 
figure;  and  the  nitrogen  as  nitrates  is  generally  from  about  0-3 
to  0-6  part  per  100,000. 

Waters  from  red  sandstone  strata  vary  considerably  in  their 
composition,  according  as  the  deposit  is  pure  or  impure,  soft 
or  hard.  The  total  solids  and  total  hardness  are  both  some- 
times high,  and  the  former  may  reach  100  parts  per  100,000; 
the  latter  is  mainly  of  a  permanent  nature,  but  the  water  may 
sometimes  be  soft  and  possess  a  total  hardness  figure  not  exceed- 
ing 10  parts  per  100,000.  The  chlorine  may  vary  from  2  to  6 
parts  per  100,000;  and  traces  of  phosphates  are  always  to  be 
detected  in  the  mineral  solids,  which  mainly  consist  of  sodium 
chloride,  carbonate  and  sulphate,  calcium  and  magnesium 
carbonates  and  sulphates,  and  a  trace  of  iron. 

Waters  from  selenitic  deposits  are  often  harmful  to  drink, 
on  account  of  the  large  proportion  of  calcium  sulphate  (10  to 
30,  or  more,  parts  per  100,000),  which  is  taken  up  from  the 
deposit — this  consisting  of  calcium  sulphate  in  clear  crystals. 

Waters  collected  from  loose  sands  are  of  variable  composition. 
Some  are  soft,  with  total  solids  of  from  only  6  to  12  parts  per 
100,000,  and  others  are  rather  hard  (permanent)  with  mineral 
solids  amounting  to  even  100  parts  per  100,000.  The  chlorine 
figure  is  generally  rather  high,  and  may  amount  to  a  high  figure 
in  some  cases.  The  mineral  solids  consist  of  sodium  chloride, 
carbonate  and  sulphate,  calcium  and  magnesium  salts,  and  traces 
of  iron  and  silica.  Those  from  gravel  are  generally  soft,  but  some 
are  hard,  with  high  total  solids. 

Waters  coming  from  a  depth  in  the  lias  clays  have  generally 
very  high  mineral  solids  (often  consisting  largely  of  calcium  and 
magnesium  sulphate).    There  is,  as  a  rule,  considerable  opacity, 


40 


HYGIENE    AND   PUBLIC   HEALTH 


and  the  physical  characters  generally  are  not  favourable  to  the 
water.  The  hardness,  which  is  almost  entirely  permanent,  is 
generally  over  20,  and  the  mineral  solids  may  reach  300  parts 
per  100,000. 

Quantity. 

The  water  supplied  to  a  community  must  be  good  in  quality 
and  abundant  in  quantity.  Impure  waters  are  liable  to  cause 
injury  to  the  health  of  those  who  drink  them;  whilst  deficiency 
of  water  means  want  of  cleanliness,  with  its  ensuing  discomforts 
and  dangers. 

Water  is  required  for  the  following  purposes,  the  under- 
mentioned quantities  representing  average  requirements: — 


Household 


/■Fluids  as  drink 
Cooking 

Personal  ablution 
Utensil  and  house  washing 
Clothes  washing  (laundry) 
.  Water  closets 
Trade  and  Manufacturing 

(Cleansing  streets     . 
Public  baths  and  fountains 
Flushing  and  cleansing  sewers 
Extinguishing  fires 


Total 


Gallons  per 
head  daily. 

0-33 

075 
5-00 
3-00 
3-00 
5-00 

S'oo 


5-00 


27-08 


The  quantities  of  water  given  above  as  required  for  the  house- 
hold are  those  which  are  necessary  to  maintain  a  good  condition 
of  cleanliness.  The  5  gallons  for  personal  ablutions  would  allow 
a  daily  sponge  bath  for  each  person.  If  each  person  has  also 
a  weekly  general  bath  of  from  30  to  40  gallons,  5  gallons  extra 
per  head  daily  must  be  added. 

In  towns,  5  gallons  per  head  daily  is  found  to  be  ordinarily 
sufficient  for  municipal  purposes;  and  the  same  amount  is 
required,  on  the  average,  for  manufacturing  and  trade  purposes. 
Water  is  also  required  for  animals  ■ —  drinking,  washing,  and 
cleansing  of  stables.  About  16  gallons  daily  for  each  horse, 
and  10  gallons  for  every  cow,  are  average  requirements. 

On  the  whole,  it  may  be  said  that  not  less  than  30  gallons 
per  head  of  the  population  should  be  supplied  to  every  town 
daily.  There  will  always  be  some  waste  in  households  from 
leaky  taps  and  fittings,  and  this  must  be  provided  for.  The 
greater  part  of  the  waste,  however,  very  often  takes  place  from 


WATER  41 

the  mains,  before  the  water  reaches  the  consumer.  In  some  towns 
it  has  been  found  that  as  much  as  one-half  or  two-thirds  of  the 
total  water  supply  has  leaked  out  of  the  mains  into  the  soil. 
The  supplies  per  head  in  the  various  towns  in  this  country  vary 
greatly. 

The  amount  of  water  actually  utilized  in  the  houses  of  a  town 
varies  enormously.  In  the  houses  of  the  poor  it  may  be  only 
2  or  3  gallons  per  head  daily;  whereas  it  should  amount  to 
at  least  15.  The  adult  human  being  consumes  daily  about 
2 1  pints  of  water  as  drink,  and  about  another  2  pints  in  his 
solid  food. 

Distribution. 

The  system  adopted  by  the  ancient  Romans  for  conducting 
the  water  collected  at  the  gathering  grounds  into  their  cities 
was  the  construction  of  masonry  aqueducts  built  on  arches, 
with  a  gentle  incline  to  allow  of  a  steady  flow  of  water  from  its 
source  to  its  outflow  in  the  city.  The  aqueducts  usually  crossed 
the  valleys  on  raised  arches,  but  the  Romans  also  knew  how  to 
construct  inverted  siphons  of  lead  piping  for  the  passage  of  the 
water  across  valleys.  The  remains  of  the  reservoirs  with  which 
the  inverted  siphons  were  connected  on  either  side  of  a  valley 
are  still  to  be  seen  in  the  neighbourhood  of  Lyons. 

The  water  supplied  by  public  companies  to  towns  in  this 
country  is  now  usually  distributed  from  their  reservoirs  through 
iron  pipes  laid  underground.  These  cast-iron  mains  are  subject 
to  much  rusting  and  corrosion,  especially  when  the  water  is  soft. 
Many  of  these  pipes  have  been  found  much  weakened  by  corro- 
sion at  some  places,  and  nearly  blocked  with  accumulated  rust 
at  others,  the  water  also  having  deteriorated  in  quality.  It 
is  now  usual  to  coat  these  pipes  with  some  material  which  is 
unacted  on  by  water,  such  as  Angus  Smith's  solution,^  or  with 
a  vitreous  glaze.  The  magnetic  oxide  of  iron  produced  on  the 
surface  of  the  metal  by  Barff's  process  is  also  occasionally  used. 
In  this  process  the  iron  pipes  are  heated  to  a  white  heat,  and 
then  exposed  to  superheated  steam  for  several  hours.  The 
practice  of  caulking  the  joints  of  iron  pipes  with  tow  or  gaskin 
next  the  interior  of  the  pipe,  and  then  running  the  joint  with 
molten  lead,  was  strongly  condemned  by  the  Rivers  Pollution 

1  Angus  Smith's  process  consists  in  heating  the  pipes  to  a  high  tempera- 
ture and  then  dipping  them  into  a  hot  varnish  consisting  of  coal-tar  pitch 
resin,  and  linseed  oil. 


42  HYGIENE    AND    PUBLIC   HEALTH 

Commissioners,  as  the  water  absorbs  impurities  from  the  tow 
and  hemp.  They  recommended  that  the  pipes  should  have 
turned  and  bored  joints,  or,  in  the  case  of  mains  large  enough 
for  a  man  to  enter,  that  the  inside  of  the  joint  should  be  pointed 
with  Portland  cement.  The  mains  should  have  scouring  valves 
at  their  dead  ends,  and  should  be  placed  at  a  minimum  depth 
of  3  feet,  so  as  to  be  protected  from  frost  and  sun.  All  the  service 
pipes  of  the  house  must  also  be  protected  from  extremes  of 
temperature,  but  they  should  always  be  left  accessible;  and  if 
concealment  is  necessary,  it  should  only  be  by  a  removable 
wooden  casing.  On  freezing,  water  expands,  and  the  pipe  may 
burst;  but  as  the  fracture  is  not  discovered  until  the  thaw  sets 
in,  there  is  a  popular  impression  that  the  thaw  is  the  cause  of 
the  pipe  bursting. 

An  enormous  amount  of  leakage  formerly  took  place  from 
water  mains  in  many  towns,  from  sHght  settling  of  the  ground 
after  laying,  or  from  the  vibration  of  heavy  traffic  causing 
fracture  of  the  pipes  and  joints.  It  has  been  estimated  that 
in  London  at  one  time  15  gallons  out  of  the  35  supplied  per 
head  daily  ran  to  waste  in  the  soil.  The  loss  is  especially  great 
where  the  supply  is  constant  and  the  mains  always  kept  under 
pressure.  If  the  spots  at  which  leakage  occurs  could  be  known, 
the  pipes  could  be  easily  taken  up  and  repaired,  but  the  difficulty 
is  to  find  where  the  leaks  are.  This  difficulty  has  been  over- 
come by  Mr.  Deacon,  who  has  invented  a  meter  which  can  be 
used  as  a  waste  detecter.  One  of  these  meters  is  placed  on  each 
district  main;  it  registers  the  flow  of  water  by  day  and  night 
and  therefore  the  waste,  for  the  water  flowing  through  the  main 
during  the  dead  of  night  is  not  used  by  the  consumers,  but  is 
running  to  waste.  Having  localized  the  waste  to  the  district 
supplied  by  a  district  main,  the  exact  spots  where  the  leakages 
are  taking  place  can  be  determined  by  the  vibrations  thereby 
produced  in  the  nearest  house  communication  pipes,  which  can 
be  distinctly  heard  on  applying  a  stethoscope  to  the  pipe.  By 
this  system,  to  take  one  example  only,  the  Lambeth  Water 
Company  reduced  its  consumption  from  34  gallons  per  head 
per  day  to  20  gallons,  the  quantity  available  to  the  consumer 
remaining  the  same. 

The  temperature  of  the  water  in  the  underground  mains 
of  a  town  varies  considerably  with  the  season  of  the  year.  In 
Chelsea,  where  the  temperature  of  the  water  in  the  mains  was 


WATER  43 

tested  daily  for  some  years,  a  minimum  temperature  of  from 
37°  F.  to  40°  F.  is  usually  recorded  in  January  or  February, 
whilst  a  maximum  of  from  68°  F.  to  74°  F.  is  usually  attained 
in  July  or  August.  The  water  temperature  follows  the  mean  air 
temperature,  but  the  changes  are  of  course  far  less  in  volume, 
and  are  effected  more  gradually.  It  would  seem  probable  that 
the  temperature  of  the  water  in  cisterns  exposed  to  the  sun  and 
atmosphere  is  likely  to  be  considerably  in  excess  of  that  drawn 
from  the  mains  during  the  warm  months  of  the  year,  so  that 
temperatures  of  80°  F.  are  probably  not  unusual  under  such 
conditions. 

The  house  communication  pipes  in  nearly  all  towns  are  of 
lead  connected  with  the  main  by  a  brass  screwed  ferrule.  Lead 
house  service  pipes  are  employed,  because  the  ductile  metal  can 
be  easily  bent  as  occasion  may  require  in  carrying  the  pipes 
through  a  house,  and  they  are  easily  jointed  and  rustless.  If 
wrought-iron  pipes  are  used,  double  screw  joints  should  be 
provided  at  convenient  points  to  admit  of  the  clearing  away  of 
the  rust,  which  often  chokes  an  unprotected  iron  service  pipe. 
Lead  pipes  may  be  acted  on  by  water,  especially  soft  water 
with  an  acid  reaction,  and  in  this  way  there  may  be  danger  to 
the  consumers.  Such  has  not  been  found  generally  to  be  the 
case,  for  although  new  lead  pipes  are  undoubtedly  acted  on  by 
soft  water,  an  oxide  of  lead  being  formed  which  rapidly  dis- 
solves again  in  the  presence  of  faint  acidity,  the  action  is  often 
very  slight.  The  Loch  Katrine  water  acts  most  powerfully  on 
lead,  and  yet  no  symptoms  of  lead-poisoning  have  ever  been 
observed  amongst  the  population  of  Glasgow.  It  is  now  recog- 
nized that  the  degree  of  plumbo-solvency  of  a  water  is  chiefly 
determined  by  the  amount  of  its  acidity,  and  that  this  acidity 
is  mainly  due  to  acid-producing  bacteria  in  peat.  A  distinction 
must  be  made  between  plumbo-solvency  and  the  "  erosion  "  of 
lead  surfaces  which  sometimes  takes  place;  the  latter  depends 
on  the  presence  of  dissolved  oxygen,  and  shows  itself  by  the 
formation  of  a  relatively  insoluble  powder  (the  oxy-hydrate  of 
lead),  which  may  tend  to  fall  away  from  the  surface,  and  so 
permit  of  progressive  action. 

The  hard  waters,  which  contain  salts  of  lime  and  magnesia, 
either  have  very  little  solvent  action  on  lead,  or  they  quickly 
coat  the  metal  with  the  basic  carbonate  or  sulphate  of  lead, 
which    prevent    further    action.     The    soft,    highly   oxygenated 


44  HYGIENE   AND   PUBLIC  HEALTH 

waters  containing  organic  matters,  peaty  acids,  nitrites,  nitrates, 
and  chlorides,  are  those  which  have  the  most  powerful  action  on 
lead,  the  oxide  of  lead  which  forms  upon  the  surface  of  the 
metal  being  constantly  dissolved  and  carried  away  in  the  water. 
Where  lead-poisoning  is  feared,  a  block-tin  pipe  or  a  cast  or 
wrought-iron  pipe  protected  by  a  coating  of  Angus  Smith's 
solution  should  be  substituted  for  the  lead  pipe.  Block-tin  pipes 
enclosed  in  lead  pipes  are  occasionally  used;  it  is  important 
that  there  should  be  no  crack  or  fracture  of  the  tin  lining, 
otherwise  galvanic  action  will  be  set  up  when  the  pipe  is  full 
of  water  and  large  quantities  of  lead  will  be  dissolved.  Great 
care,  moreover,  is  necessary  in  making  the  joints  on  this  kind 
of  piping,  as  the  heat  necessary  for  making  a  joint  in  the  lead 
pipe  is  liable  to  melt  the  tin.  To  obviate  this  a  layer  of  asbestos 
is  sometimes  introduced  between  the  lead  and  tin,  this  serving 
to  keep  the  metals  apart.  Polluted  shallow  well  waters  have 
sometimes  been  known  to  have  a  very  powerful  and  persistent 
solvent  action  on  lead,  probably  from  their  containing  excess 
of  carbonic  acid,  which  tends  to  dissolve  the  coating  of  carbonate 
of  lead  formed  in  the  pipe  or  cistern. 

It  has  been  suggested  that  the  varying  powers  of  corroding 
lead,  exhibited  by  soft  waters  of  apparently  identical  chemical 
composition,  are  influenced  by  the  presence  or  absence  of  silica 
in  the  water.  When  silica  is  present,  even  in  the  proportion 
of  only  half  a  grain  per  gallon,  the  action  on  lead  is  said  to  be 
very  slight.  There  must  be  no  excess  of  alkali  in  the  water,  or 
this  inhibitive  action  of  silica  is  not  displayed.  By  passing 
distilled  waters  and  other  soft  waters  known  to  have  a  corrosive 
action  on  lead  through  a  filter  formed  of  layers  of  sand,  and 
broken  limestone,  enough  silica  is  taken  up  to  reduce  the  lead- 
corrosive  power  very  considerably.  Recent  experiment,  how- 
ever, seems  to  show  that  the  alkaline  carbonate,  which  may  be 
taken  up  from  the  limestone,  may  be  an  even  more  important 
factor  than  the  silica.  The  waters  of  several  large  towns,  which 
have  a  considerable  effect  on  new  lead,  have  been  rendered  nearly 
inactive  by  neutralizing  the  acid  present  by  a  solution  of  sodium 
carbonate  or  by  slaked  lime.  The  solvent  properties  of  these 
waters  are  believed  to  be  mainly  due  to  the  presence  of  peaty 
acids  (humic,  ulmic,  etc.),  and  if  the  acidity  is  thus  neutralized 
the  plumbo-solvent  action  of  the  water  is  much  reduced.  After 
the   prolonged   drought   of   1887,   the   waters   in   the   Sheffield 


WATER  45 

reservoirs  ran  very  low,  the  peaty  acids — derived  from  the 
gathering-grounds — were  not  diluted  to  the  usual  extent,  and  a 
severe  outbreak  of  lead-poisoning  occurred  in  the  town.  In  rare 
cases  the  acidity  which  gives  the  water  its  lead-dissolving  powers 
may  be  due  to  the  presence  of  free  sulphuric  acid  formed  by 
oxidation  of  iron  pyrites,  when  the  water  drains  off  rocks  rich  in 
that  substance.  It  was  suggested  by  Power,  in  a  report  to  the 
Local  Government  Board,  that  the  biological  characteristics  of 
a  water — the  presence  or  absence  of  bacterial  organisms — may 
exercise  an  influence  over  its  "  plumbo-solvent  "  properties; 
but  this  is  probably  true  only  in  so  far  as  the  production  of 
acidity  in  peaty  matter  is  the  result  of  micro-organic  life. 

Having  regard  to  the  importance  of  acidity  as  affecting 
plumbo-solvency,  on  some  gathering-grounds  measures  are  taken 
to  divert  the  most  acid  feeders  of  the  general  upland  surface 
supply,  and  so  avoid  the  inclusion  of  the  more  plumbo-solvent 
waters  in  the  general  supply.  There  is  also  some  evidence  to 
show  that  leaden  pipes  are  much  more  rapidly  corroded  when 
the  mains  are  intermittently  charged,  than  when  kept  under 
constant  high  pressure. 

Water  companies  supply  Vv^ater  to  their  customers  either  on 
the  constant  or  the  intermittent  system.  Under  the  former,  the 
aim  is  to  keep  the  mains  constantly  charged  with  water  under 
pressure,  so  that  the  house  pipes  being  also  always  charged,  no 
storage  of  water  on  the  premises  of  the  consumer  is  required. 
The  only  cisterns  which  should  be  required  in  a  house  supplied 
with  a  constant  service  of  water  are  small  cisterns  or  water- waste 
preventers  for  flushing  water-closets,  and  a  small  cistern  to 
supply  water  to  the  kitchen  boiler.  Under  the  intermittent 
system,  the  flow  of  water  in  the  mains  is  stopped,  except  for  a 
short  period  of  every  day,  by  the  turncock.  The  house  pipes 
are  only  charged  when  the  water  is  flowing  in  the  main,  and 
consequently  water  must  be  stored  for  use  on  the  premises  when 
the  pipes  are  empty. 

The  great  fault  of  the  intermittent  service  is  that  water  must 
be  stored  on  the  premises  of  the  consumer.  Water  stored  in 
small  receptacles,  even  under  the  most  favourable  circumstances, 
deteriorates;  it  loses  its  aerated  character,  may  become  flat  and 
insipid,  and  collects  impurities  from  the  air.  In  the  houses  of 
the  poor,  water  is  often  stored  in  the  most  filthy  receptacles — 
wooden  butts  and  tubs,  rotten  and  decayed  within,  or  cisterns 


46  HYGIENE    AND    PUBLIC   HEALTH 

exposed  to  the  air,  which  are  the  receptacles  of  all  sorts  of  filth 
and  rubbish.  The  situations  in  which  cisterns  are  often  found 
on  such  property  are  the  immediate  vicinity  of  the  w.c,  and 
beneath  landing  floors,  staircases,  or  even  bedroom  floors.  Even 
in  the  better-class  houses  cisterns  are  sometimes  placed  in  the 
most  improper  places,  as  under  stairs  or  floors,  where  dust  and 
dirt  fall  into  them,  or  inside  water-closets,  where  the  air  is  at 
times  charged  with  foul  gases. 

Another  disadvantage  of  the  intermittent  service  is  that  the 
capacity  of  the  cistern  is  often  utterly  inadequate — especially 
in  tenement  houses,  occupied  by  numerous  poor  families — for 
the  wants  of  the  people  who  depend  upon  it  as  their  only  source 
of  supply.  Moreover,  the  intermittent  charging  favours  corrosion 
of  the  service  pipes. 

The  same  cistern  is  far  too  frequently  used  to  flush  water- 
closets  as  well  as  to  supply  the  drinking  water,  which  may  become 
polluted  in  this  way  {see  Chapter  II). 

Another  method  by  which  drinking  water  in  cisterns  becomes 
liable  to  pollution,  is  the  practice  —  now,  fortunately,  but 
seldom  seen — of  connecting  the  "  standing  waste,"  or  overflow 
pipe  of  a  cistern  with  a  drain  or  soil  pipe  of  the  house,  or  with 
a  D  trap  under  a  water-closet  {see  Chapter  II).  The  overflow 
pipe  from  the  cistern  should  discharge  in  the  open  air  as  a  warning 
pipe — at  some  point  where  it  is  not  exposed  to  polluted  air. 

Besides  the  danger  of  pollution  of  water  in  cisterns  by  sewer 
air,  dust,  soot,  and  accidental  contaminations  such  as  dead 
mice,  birds,  or  cockroaches,  the  material  of  which  the  cistern 
is  composed  is  an  important  factor  as  regards  the  purity  of  the 
water  stored  in  it.  Iron  cisterns  rust  and  discolour  the  water; 
zinc  is  occasionally  dissolved  in  small  quantities  by  water; 
lead  is  dissolved  at  first  when  the  cistern  is  new,  but  rapidly 
becomes  coated  with  carbonate  or  sulphate  of  lead  when  the 
water  is  hard.  The  deposit  forms  a  lining  which  protects  the 
surface  of  the  metal  from  further  action,  and  it  is  for  this  reason 
that  the  inside  of  a  leaden  cistern  should  never  be  scraped  when 
tlie  cistern  is  being  cleaned  out.  A  lead  cistern  may  be  pro- 
tected against  the  action  of  soft  water  by  coating  it  with  lime 
from  time  to  time.  Galvanized  iron  is  largely  used  for  cisterns; 
it  is  light,  cheap,  and  durable,  and  generally  perfectly  safe,  but 
has  been  known  to  give  up  a  trace  of  zinc  to  the  water.  In 
galvanizing  iron,  the  metal  is  first  washed  in  a  weak  solution  of 


WATER  47 

vitriol  and  cleansed  and  dried;  it  is  then  placed  in  a  vessel 
containing  molten  zinc,  which  adheres  to  it  and  forms  a  coating. 
Wrought-iron  cisterns  covered  with  a  vitreous  enamel  may 
also  be  safely  used.  Slate,  though  heavy,  is  a  good  material 
for  cisterns,  but  the  cemented  joints  of  the  five  slabs  must  not 
be  repaired  with  rod  lead  when  they  leak,  as  they  often  do ;  for 
both  white  lead  (a  mixture  of  carbonate  and  oxide)  and  red 
lead  (an  oxide)  are  soluble  in  water.  Glazed  or  vitrified  stone- 
ware and  fireclay  cisterns,  though  heavy,  are  very  valuable, 
as  they  give  up  nothing  to  water,  and  no  joints  are  necessary. 
In  selecting  them,  however,  care  should  be  taken  that  the 
enamelling  or  glazing  is  not  rough  or  fractured.  Enamelled  iron, 
glass  lined  iron,  and  tinned  copper  cisterns  have  been  made. 
Water  should  never  be  left  in  contact  with  wood,  as  wood, 
when  constantly  wet,  rapidly  rots,  and  forms  a  breeding  place 
for  minute  worms  and  other  animal  organisms  and  fungi. 

To  indicate  briefly  the  conditions  under  which  water  may  be 
safely  stored  in  houses: — {a)  The  cistern  should  be  of  stone- 
ware, slate,  or  galvanized  iron;  (6)  it  should  be  placed  in  a  light 
and  well  ventilated  position,  and  should  be  properly  covered; 
(c)  it  must  not  be  used  to  flush  water-closets,  but  may  supply 
the  "  intercepting  "  or  waste-preventing  cisterns  which  should 
be  used  for  this  purpose;  [d)  the  overflow  pipe  must  be  carried 
out  into  the  open  air  to  terminate  as  a  warning  pipe;  {e)  the 
cistern  should  be  cleaned  out  at  least  once  in  every  three  months, 
and  should  be  reasonably  accessible  for  this  purpose. 

Cisterns  are  occasionally  used  to  supply  water-closets  which 
have  regulator  valves  on  the  supply  pipes  near  to  the  closet 
basin.  Although  there  is  but  little  danger  by  this  arrangement 
of  foul  air  finding  its  way  into  the  drinking  water  of  the  cistern, 
as  the  supply  pipe  is  always  full  of  water  unless  the  cistern  is 
empty,  still,  it  is  better  to  break  the  connection  altogether 
between  drinking  water  cisterns  and  water-closets. 

The  advantages  of  an  intermittent  over  a  constant  service 
are  that  there  is  less  waste  inside  houses,  and  that  the  service 
of  pipes,  taps  and  fittings,  need  not  be  so  strong  as  for  a  con- 
stant service.  This  latter  point  has  been  disputed,  as  regards  the 
pipes,  on  the  ground  that  there  is  a  greater  strain  on  the  pipes 
where  the  water  is  suddenly  turned  on  or  off  with  a  common 
stop-cock,  than  where  it  is  slowly  turned  on  or  off  by  the  screw- 
down  tap  used  with  a  constant  service ;  but  it  must  be  remem- 


48  HYGIENE    AND    PUBLIC   HEALTH 

bered  that  with  a  constant  service  the  water  in  the  house  pipes 
is  under  a  much  higher  pressure  than  where  the  pipes  are  con- 
nected with  a  cistern  in  the  house.  There  is  less  danger,  also, 
with  an  intermittent  service,  of  the  higher  parts  of  the  town 
being  without  water  on  account  of  great  waste  in  the  low-lying 
parts,  as  sometimes  occurs  with  a  constant  service. 

A  merit  often  claimed  for  the  constant  service  is  that  no  storage 
is  required  on  the  premises  of  the  consumer.  The  water  drawn 
from  the  taps  on  the  house  pipes  is  clear,  cool,  and  sparkling, 
in  the  same  condition  as  it  leaves  the  street  mains,  and  the 
supply  is — or  should  be — abundant  and  never-failing.  But  ex- 
perience has  shown  that  it  is  generally  desirable  to  retain  or 
provide  some  means  of  storing  water  on  the  premises,  to  meet 
requirements  when  the  supply  is  cut  off  on  account  of  repairs  to 
the  main  or  by  frost. 

In  houses  supplied  by  a  constant  service  it  is  a  good  plan  to 
obtain  a  direct  supply  for  drinking  purposes  from  a  draw-off 
tap  fixed  on  the  service  pipe  on  its  way  to  the  cistern,  when  the 
latter  is  retained  as  a  means  of  storage. 

It  has  been  suggested  that  the  shape  of  the  cistern  in  common 
use  should  be  modified  to  that  of  a  cylinder,  ending  below  in 
an  inverted  cone,  with  a  draw-off  pipe  at  its  bottom  to  admit 
of  the  flushing  away  of  any  deposit  which  accumulates;  the 
service  pipe  from  the  cistern  to  be  soldered  into  the  side  like 
the  present  overflow  pipe,  but  of  course  lower  down,  and  the 
lid  to  be  tightly  fitting. 

In  actual  practice  in  many  cases,  the  advantages  of  a  constant 
service  have  been  somewhat  mitigated  by  errors  on  the  part  of 
both  consumers  and  water  companies.  Unless  constant  inspec- 
tion is  exercised  and  the  taps  and  fittings  in  houses  frequently 
supervised,  there  is  great  waste.  This  occurs  especially  in  cases 
where  an  intermittent  service  has  been  changed  to  a  constant 
service,  and  the  old  pipes  and  fittings  have  been  retained.  Not 
only  this,  but  where  water-closets  are  flushed  by  a  pipe  and  tap 
direct  from  the  house  main,  without  the  intervention  of  a  cistern 
or  water-waste  preventer— a  not  unusual  occurrence  in  poor 
neighbourhoods — there  is  great  danger  of  foul  air,  or  even  liquid 
filth,  being  sucked  up  into  the  empty  pipe  when  the  tap  is  left 
unscrewed,  and  so  finding  its  way  into  the  water  main  of  a 
district.  The  suction  is  due  to  a  partial  vacuum  being  created 
in  the  water  mains  when  the  water  is  turned  off,  owing  to  the 


WATER  49 

water  finding  its  way  through  leaky  joints  into  the  soil,  or  Irom 
the  mains  being  emptied  by  taps  on  house  pipes  at  a  lower 
level.  Sueli  occurrenees  are  believed  to  have  given  rise  to  out- 
breaks of  enteric  fever  at  Croydon,  Cambridge  (Caius  College), 
Sherborne,  and  other  places.  They  demonstrate  the  absolute 
necessity  of  breaking  the  connection  between  water-closets  and 
water  mains  by  the  interposition  of  a  small  cistern  or  water  waste- 
preventer. 

In  some  cases  of  constant  service,  water  companies  try  to 
economize  by  insisting  on  the  insertion  of  a  throttle  of  very 
small  diameter  (i  to  y,,  inch)  into  the  house  communication  pipe, 
with  the  result  that  water  merely  dribbles  out  of  the  house 
taps  when  they  are  full  on.  In  any  case,  screw-down  taps  must 
be  substituted  for  common  taps,  and  a  screw-cock  must  be 
placed  on  the  house  pipe,  where  it  enters  the  premises,  to  shut 
off  the  water  in  case  of  a  pipe  bursting.  A  drip-tap  should 
also  be  placed  on  a  pipe  at  the  lowest  part  of  the  system,  by 
which  it  may  be  emptied  during  frost.  All  the  leaden  service 
pipes  of  a  house  should  be  strong  (12  pounds  per  lineal  yard 
for  i-inch  pipes,  and  6  pounds  per  lineal  yard  for  |-inch  pipes), 
in  order  to  withstand  the  constant  pressure  to  which  they  are 
subjected.  If  pressure  is  maintained  in  the  mains  by  pumping, 
and  not  by  storage  in  a  high-level  reservoir,  greater  power 
must  be  used  in  the  morning  of  every  day,  this  being  the  time 
when  the  largest  quantities  of  water  are  drawn  for  domestic  use. 
The  waste  of  water  can  be  overcome  by  the  use  of  Deacon's 
waste-water  meter  on  the  district  mains,  and  by  frequent  super- 
vision of  house  taps  and  fittings.  The  supply  of  water  by  meter 
would  tend  greatly  to  check  waste,  but  is  not  advisable  in  the 
case  of  poor  populations,  as  the  inevitable  stinting  of  water  that 
would  follow  would  have  great  sanitary  disadvantages.  For 
trade  purposes  it  is  the  most  just  and  reasonable  method. 
Water  meters  are  either  "  positive,"  and  indicate  the  amount 
of  water  supplied  by  the  number  of  times  a  cylinder  of  known 
capacity  is  filled,  as  shown  on  a  dial;  or  they  are  "  inferential," 
when  the  amount  of  water  which  has  passed  through  them  is 
inferred  from  the  velocity  of  the  flow,  as  registered  on  a  dial. 

There  is  one  danger  to  which  water  mains  are  subject,  which 
has  not  yet  been  alluded  to.  If  water  mains  and  sewers  or 
house  drains  are  laid  in  the  same  trench,  there  is  a  possibility 
of  foul  matters,  which  have  escaped  into  the  soil  from  leaky 
drains  or  sewers,  being  sucked  into  the  water  mains,  if  these 

4 


50  HYGIENE   AND    PUBLIC    HEALTH 

are  in  any  way  defective,  during  intermissions  in  the  service. 
Such  intermissions  arc  the  daily  occurrences  of  an  intermittent 
service,  and  are  olten  unavoidable  with  a  constant  service  for 
executing  necessary  repairs  to  the  pipes.  In  a  similar  manner, 
too,  water  mains  may  suck  in  from  the  surrounding  soil  coal 
gas  which  has  escaped  from  leaky  gas  pipes  and  mains.  It  is 
not  only,  however,  during  intermissions  in  the  service  that 
such  accidents  may  occur,  for  experiments  prove  that  there  is 
a  partial  vacuum  inside  water  pipes  in  the  immediate  neighbour- 
hood of  defective  joints,  whenever  the  water  is  flowing  in  the  pipes. 
The  water  and  sewerage  sj^stems  must  be  kept  as  far  apart  as 
possible.  Rats  have  been  known  to  burrow  from  a  drain  or  sewer 
to  an  underground  water  supply  in  search  of  water,  lead  water 
pipes  being  frequently  found  gnawed,  and  sometimes  perforated. 
With  a  constant  service  the  mains  are  always  charged  in  case 
of  fire;  with  an  intermittent  service  much  valuable  time  is 
often  lost  in  finding  the  turncock. 

Purification  of  Water. 

It  is  highly  desirable  that  the  water  supply  of  a  community 
should,  as  far  as  possible,  be  kept  free  from  all  foreign  and 
polluting  ingredients.  Nearly  all  waters  derived  from  natural 
sources  contain  such  ingredients,  and  the  various  processes  of 
purification  aim  at  their  elimination.  The  foreign  ingredients 
may  be  divided  broadly  into  mineral  and  organic  matters.  The 
removal  of  the  salts  producing  hardness  and  the  production  of 
softer  water  is  eminently  desirable  for  economic  purposes,  and 
occasionally  to  improve  the  potability  and  wholesomeness  of 
the  water  when  the  salts  are  in  great  excess.  The  removal  of 
the  organic  matters,  suspended  or  dissolved  in  water,  is  another 
and  still  more  important  object  in  any  process  aiming  at  com- 
plete purification.  We  shall  now  proceed,  first,  to  the  con- 
sideration of  those  processes  which  are,  or  could  be,  undertaken 
on  a  large  scale  for  the  purification  of  water  before  its  distribution 
to  the  consumers;  and,  secondly,  to  such  processes  of  domestic 
purification  as  may  be  undertaken  on  his  own  premises  by  the 
consumer. 

What  should  be  aimed  at,  however,  is  to  procure  at  its  source 
a  water  sufficiently  good  to  require  no  artificial  purification; 
but  failing  this,  the  water  should  be  efficiently  purified  before 
its  distribution  to  the  consumers.  It  is  certainly  not  wise  to 
leave  the  purification  to  individual  initiative. 


WATER  51 

Purification  on  a  Large  Scale. — There  are  several  processes 
(Clark's,  Porter-Clark's,  Maignen's,  Howatson's,  etc.)  which  aim 
at  the  removal  of  the  mineral  matters  (the  salts  of  lime  and 
magnesia)  from  a  water.  The  fundamental  basis  of  them  all  is 
the  addition  of  hme  water.  When  a  certain  quantity  of  lime 
water  is  thoroughly  mixed  with  a  hard  water,  it  combines 
with  the  carbonic  acid  holding  the  chalk  in  solution,  with  the 
result  that  the  new  carbonate  thus  formed  is  precipitated, 
together  with  the  original  chalk.  In  this  way  chalk  well  waters 
of  20°  of  hardness,  and  Thames  water  (16°),  may  be  reduced 
to  4°  or  5°.  The  hardness  thus  got  rid  of  is  due  to  the  pre- 
cipitation of  chalk,  and  chalk  alone;  it  is  temporary  hardness, 
and  the  same  effect  would  be  produced  on  the  water  by  sufficient 
boiling. 

The  working  of  the  process  (Clark's)  may  be  described  shortly 
as  follows: — One  ounce  of  quicklime  to  every  700  gallons  of 
water  is  used  for  each  degree  of  temporary  hardness.  The  lime 
in  the  form  of  quicklime  is  first  slaked  with  water  in  a  tank, 
into  which  the  water  to  be  softened  is  gradually  allowed  to  flow ; 
thorough  mixing  must  be  insured  by  wooden  paddles  or  other 
mechanical  means.  The  water  becomes  milky  in  appearance 
from  precipitation  of  the  chalk,  and  must  then  be  allowed  to 
settle  for  twelve  hours,  the  supernatant  clear  water  being 
subsequently  drawn  off.  Besides  chalk,  a  certain  amount  of 
colouring  and  organic  matters  are  removed  from  the  water  by 
this  process.  It  is  important  that  uncombined  lime  should 
not  pass  out  with  the  purified  water,  as  would  be  the  case  if 
lime  were  added  in  excess  of  that  required  to  combine  with 
all  the  carbonic  acid  holding  the  chalk  in  solution.  To  detect 
uncombined  lime,  it  is  only  necessary  to  add  a  few  drops  of  a 
solution  of  nitrate  of  silver  to  the  treated  water  in  a  shallow 
white  dish,  when  a  brownish  colour  is  produced  if  uncombined 
lime  is  present,  but  only  a  white  precipitate  of  chloride  of  silver 
if  there  is  none  present. 

Lime  is  also  used  as  the  precipitating  agent  in  Porter-Clark's 
process;  but  the  suspended  particles  of  chalk  are  removed,  not 
by  settlement,  but  by  filtration  through  a  series  of  Unen  cloths 
in  a  filter  press  under  high  pressure.  The  plant  includes  two 
vertical  cylinders  and  a  filter  press.  In  the  first  cylinder  there 
is  a  continuous  preparation  of  lime  water,  which  is  mixed  in 
the  second  cyhnder  with  the  hard  water.  The  precipitant 
formed   is   then   separated   by  the  press.     The  process  is  expe- 


52  HYGIENE  AND  PUBLIC  HEALTH 

ditious,  and  very  effective  in  removing  lime  and  suspended 
matters  from  the  water.  It  is  one  of  the  best  means  of  softening 
water  on  a  large  scale. 

In  Atkins's  process,  which  is  somewhat  similar,  arrangements 
are  made  for  cleansing  the  cloth  filters  by  means  of  revolving 
brushes  which  play  on  the  surface  of  the  discs. 

The  Stanhope  Water  Softener  aims  at  reducing  both  the 
temporary  and  permanent  hardness,  hme  and  soda  being  used. 
The  caustic  soda  somewhat  reduces  the  permanent  hardness 
by  converting  some  of  the  calcic  or  magnesic  sulphates  into 
sulphate  of  soda.  Clarification  is  effected  b}^  subsidence  in  high 
tanks  containing  numerous  funnel-like  shelves,  one  above  the 
other,  which  collect  the  deposit  and  direct  it  to  the  bottom  of 
a  tank. 

Howatson's  process  is  very  similar.  In  this  process  the 
deposit  is  removed  by  opening  valves  in  the  hopper  bottoms  of 
the  tanks. 

In  the  Maignen  Automatic  Softener  a  small  motor  is  worked 
by  the  water,  and  this  regulates  the  amount  of  anticalcaire, 
which  mixes  with  the  water  in  a  small  tank.  Sedimentation 
takes  place  in  a  second  small  tank,  in  which  provision  is  made 
for  flushing  out  the  deposited  chalk ;  and  finally  the  water  passes 
through  a  filtre  rapide  into  a  storage  tank.  The  precipitating 
agent,  anticalcaire,  contains  hme,  sodium  carbonate,  and  alum. 
A  small  plant  suitable  for  use  in  a  dwelling  house  is  also  made. 

The  Lawrence  process  of  softening  and  sterilizing  water  is 
ingenious  and  effective.  In  this  apparatus  the  water  is  boiled, 
and  therefore  softened  and  sterilized;  the  steam  is  condensed  by 
the  cold  water  entering  the  boiler,  which  takes  up  the  heat  from 
the  steam,  and  thereby  an  important  economy  is  effected  in  the 
heat  required. 

The  process  of  filtration  through  sand  or  gravel  on  a  large  scale, 
as  carried  out  by  the  Metropolitan  Water  Board,  has  already 
been  described  {see  p.  14).  Suspended  matters,  both  mineral 
and  organic,  are  very  effectually  removed  by  sand  filtration. 

Spongy  iron,  which  is  porous  metallic  iron,  obtained  by  roasting 
haematite  iron  ore,  has  a  very  similar  action  on  dissolved  organic 
matters  in  water  to  that  exerted  by  magnetic  carbide  of  iron ; 
and,  like  magnetic  carbide  also,  it  yields  nothing  to  water  except 
a  little  iron,  which  may  be  removed  by  subsequent  filtration 
through  sand.  Spongy  iron  retains  its  properties  for  a  long 
period,  but  requires  periodical  renewal,  especially  when  used, 


WATER  53 

as  it  generally  is,  as  a  mechanical  filter  for  separating  suspended 
matters  from  water,  as  well  as  a  chemical  purifier.  Spongy  iron 
separates  lead  from  water,  but  has  no  effect  on  other  mineral 
matters. 

The  property  possessed  by  spongy  iron  and  the  magnetic 
carbide  and  oxide  of  iron  of  yielding  nothing  to  water — no 
phosphates  or  other  germ  nutrients — is  a  valuable  one;  for  the 
water  after  filtration  can  be  stored  for  a  time  without  any  great 
deterioration  from  growth  of  microscopic  organisms.  The 
especial  fitness  of  the  magnetic  carbide  of  iron  or  of  polarite  for 
filtering  a  town  water  supply  on  a  large  scale  lies  in  the  fact 
that,  when  once  the  beds  of  these  materials  are  in  situ,  they  need 
not  be  disturbed  or  renewed,  and  thus  an  enormous  amount  of 
labour  and  expense  is  avoided.  The  aeration  by  intermittent 
filtration,  which  is  essential  for  magnetic  carbide  of  iron  if  it  is 
to  retain  its  oxidizing  properties,  must  not  be  practised  with 
spongy  iron,  as  the  latter  cakes  on  exposure  to  the  air. 

At  Antwerp  and  other  places  on  the  Continent  scrap  iron 
(Anderson's  process)  is  now  being  used  for  filtering  water  on  a 
large  scale.  The  scraps  of  iron  are  placed  in  a  cylinder,  which 
is  caused  to  revolve  on  its  long  axis.  The  inner  circumference 
of  the  cylinder  is  provided  with  short  curved  shelves  reaching 
from  end  to  end,  which,  when  the  cylinder  is  revolving,  serve  to 
direct  a  shower  of  iron  through  the  water  as  it  passes  through 
the  apparatus.  The  water  is  then  exposed  to  the  air  by  flowing 
along  a  trough,  so  as  to  cause  a  precipitate  (as  ferric  oxide)  of 
the  iron  taken  up  in  the  revolving  cylinder,  and  this  precipitate 
as  it  settles  carries  down  organic  matter  with  it.  The  precipitate 
is  subsequently  removed  by  filtration  through  sand. 

The  Sterilization  of  Water  on  a  Large  Scale. — There  are  three 
processes,  now  actually  available,  by  which  water  can  be 
sterilized  on  a  large  scale,  namely  (i)  chlorination,  (2)  ozonization, 
and  (3)  the  action  of  ultra-violet  rays. 

(i)  Chlorination. — A  water  of  fair  chemical  purity  and  free  from 
suspended  matter  can  be  sterilized  effectually — certainly  as 
regards  B.  coli  and  other  organisms  of  intestinal  type — by  the 
addition  of  a  solution  of  hypochlorite  of  calcium,  sodium,  or 
magnesium,  so  that  there  is  present  finally  in  the  water  i  to 
2  parts  per  million  of  available  chlorine.  The  chlorine  should 
be  allowed  to  act  on  the  microbes  present  in  the  water  for  about 
half  an  hour.  The  carbonic  acid  naturally  present  in  the  water 
liberates  hypochlorous  acid  from  the  hypochlorite  of  calcium,  etc. 


54  HYGIENE    AND    PUBLIC    HEALTH 

The  chlorination  of  water  has  been  found  very  effective  in 
controlHng  epidemics  of  enteric  fever,  as  at  Lincoln  in  1905,  where 
the  town  water  suppl}^  was  polluted.  Not  only  is  the  water 
supply  steriUzed,  but  the  water  mains  and  pipes  through  which 
polluted  water  has  passed  are  rendered  non-infective  by  this 
process.  In  such  a  method,  however,  not  only  are  comparatively 
large  amounts  of  chlorine  added  to  the  water  (i  in  50,000  at 
Lincoln),  but  the  chlorine  is  still  present  in  the  water  as  supplied 
to  the  consumer,  giving  the  water  a  very  disagreeable  taste  and 
flavour. 

In  a  permanent  chlorination  installation  it  is  necessary  to 
remove  the  residual  chlorine  before  the  water  enters  the  mains 
to  supply  the  consumers.  This  can  be  done  by  means  of 
bisulphite  of  soda,  but  is  now  more  effectually  accomplished  by 
passing  the  sterilized  water  through  filters  containing  vegetable 
charcoal,  which  absorb  the  residual  chlorine,  and  remove  all 
odour  and  taste  from  the  chlorinated  water. 

The  chlorination  process  is  very  much  less  costlj'  than  treat- 
ment by  sand  filters,  and,  if  properly  carried  out,  offers  a  surer 
guarantee  of  the  removal  of  all  deleterious  organisms  than  any 
system  of  sand  filtration,  unless  the  water  has  been  previously 
stored  for  three  or  four  weeks  in  storage  reservoirs  and  thoroughly 
sedimented.  It  is  especially  applicable  in  the  case  of  river 
waters,  which  are  liable  at  times  to  sewage  contamination.  If 
the  water  is  at  all  turbid,  it  should  be  clarified  by  filtration 
through  small  beds  of  sand  or  polarite  prior  to  chlorination. 

The  mixing  of  the  hypochlorite  solution  with  the  water  is 
best  effected  in  a  hopper  tank  of  known  capacity,  the  hypochlorite 
in  measured  volume  being  placed  in  the  tank  prior  to  the  entrance 
of  the  water.  The  inward  rush  of  the  water  effectually  mixes 
the  hypochlorite  solution  with  the  water  to  be  acted  upon,  and, 
after  standing  at  rest  for  half  an  hour,  the  sterilized  water  is 
evacuated  from  the  tank  and  filtered  through  a  layer  of  granite 
chips,  and  then  through  charcoal  for  the  removal  of  any  free 
chlorine.  B.  coli  should  invariably  be  absent  from  the  water 
so  treated  in  100  c.c. 

The  chlorination  process  has  already  been  adopted  largely 
in  the  United  States  for  town  supplies,  and  is  now  coming  into 
use  in  this  country. 

(2)  Ozonization. — This  process  has  been  tried  on  the  Continent 
with  success,  but  has  not  been  much  taken  up  in  this  country. 
The  electrical  installation  for  the  generation  of  ozone  gas  in 


WATER  55 

quantities  sufficient  to  sterilize  large  volumes  of  water  is  both 
expensive  and  complicated,  and  the  treated  water  has  a  dis- 
agreeable taste  until  it  has  been  allowed  to  stand  for  a  con- 
siderable time. 

Ozonized  air  is  produced  by  ozonizers — appliances  in  which 
silent  electrical  discharges  are  made  to  pass  through  a  space 
V.v  inch  wide  between  glass  and  aluminium  cylinders  (Siemens 
de  Frise  type).  Air  enters  at  the  bottom  of  the  ozonizers, 
traverses  the  space  where  the  silent  discharges  are  occurring, 
and  issues  at  the  top  charged  with  ozone.  This  ozonized  air 
is  introduced  into  the  water  to  be  treated  through  an  injector 
into  a  pipe  conveying  the  water,  and  the  mixed  air  and  water 
then  pass  into  the  bottom  of  a  tall  cylinder  or  sterilizing  tower, 
divided  at  regular  intervals  by  horizontal  diaphragms  consisting 
of  perforated  celluloid  trays,  whereby  the  ascending  currents 
of  gas  and  water  are  intimately  mixed.  The  volume  of  ozonized 
air  should  be  about  40  per  cent,  of  the  volume  of  water  to  be 
treated.  The  water  issues  at  the  top  of  the  sterilizing  tower, 
and  is  received  into  an  open  enamelled  iron  collecting  tank.  In 
the  De  Frise  process,  of  which  the  above  is  a  description,  at  the 
St.  Maur  Municipal  Waterworks,  Paris,  oxides  of  nitrogen,  peroxide 
of  hydrogen,  and  chlorine  were  not  found  in  the  treated  water  by 
Rideal  {Journal  of  the  Royal  Sanitary  Institute,  January,  1909) . 

Some  of  the  ozone  in  the  water  attacks  and  destroys  organic 
matter,  and  some  passes  again  into  the  air  at  the  top  of  the 
sterilizing  tower,  and  can  be  here  recovered  and  returned  to  the 
ozonizers.  Some  remains  in  the  water,  but  disappears  in  the 
course  of  an  hour  or  two.  Ozonization  destroys  all  but  the 
more  resistant  spore  forms  of  water  bacteria  present.  B.  colt 
and  alhed  intestinal  organisms  are  entirely  eliminated.  Unless 
the  water  is  of  distinctly  good  quality  chemically,  a  previous 
filtration  is  necessary,  otherwise  all  the  ozone  may  be  used  up 
in  oxidizing  organic  matter,  and  the  germicidal  action  is  rendered 
ineffective. 

(3)  The  Ultra-Violet  Rays. — Experiments  conducted  by  Miguel 
showed  that  in  clear  and  bright  water  B.  coli  is  killed  in  from 
15  to  20  seconds  by  exposure  to  the  ultra-violet  rays  proceeding 
from  a  mercury  vapour  lamp.  B.  typhosus  is  killed  in  from 
10  to  20  seconds,  and  the  Cholera  vibrio  in  from  10  to  15  seconds. 
The  water  must  be  bright  and  clear,  without  trace  of  suspended 
matter,  and  the  thickness  of  the  film  of  water  penetrated  by  the 
light  must  be  small. 


56 


HYGIENE    AND    PUBLIC   HEALTH 


The  mercury  arc  vapour  lamp  used  in  this  installation  is 
enclosed  in  a  tube  of  fused  rock  crystal  or  transparent  quartz, 
which  permits  the  passage  of  the  ultra-violet  rays  of  the  source 
of  illumination,  glass  being  a  complete  absorber  of  these  rays. 
The  mercury  is  vaporized  by  the  passage  of  an  electric  current. 
The  lamp  is  placed  in  a  special  cast-iron  chamber,  divided  into 
compartments  by  diaphragms,  which  cause  the  water  to  be  treated 
to  pass  in  close  contact  with  the  quartz  tube.  The  time  of 
exposure  to  the  light  should  be  sufficient  to  destroy  all  organisms 
of  intestinal   type.     An   automatic   deviating  valve  should  be 


Fig.  io. — Mercurial  Vapour  Lamp  for  Sterilizing  Water. 

E,  Sterilizing  chamber,  with  baffles  for  directing  the  flow  of  water ;  L,  lamp- 
box  fitted  with  three  windows  of  cut  rock  crystal;  O,  wing-nuts  for 
securing  box;  R,  supply  valve  to  apparatus;  V,  deviation  valve  con- 
nected with  solenoid  (5),  which  is  energized  by  the  current  to  the 
lamp.  Should  the  current  be  cut  off,  the  valve  opens,  and  the  water 
ceases  to  pass  to  the  sterilizing  chamber. 

fitted  to  the  apparatus,  to  insure  that  no  water  passes  through 
the  sterilizing  chamber  when  the  lamp  is  not  in  operation. 

The  process  has  the  advantage  over  chlorine  and  ozone  that 
nothing  of  a  chemical  nature  is  added  to  the  water,  and  that 
sterilization  is  insured  if  the  bacterial  contents  of  the  water 
are  known,  and  the  time  of  exposure  to  the  rays  thereby  adjusted. 
On  the  other  hand,  turbidity  of  the  water,  or  the  presence  of 
colloidal  matter,  seriously  interfere  with  sterilization,  as  the 
microbes  are  sheltered  from  the  action  of  the  rays  by  such 
material;  and,  in  addition,  the  deposit  of  a  brownish  sediment 
from  the  water  on  the  transparent  quartz  tube,  which  occurs 
sooner  or  later  with  all  waters,  diminishes  in  corresponding 
degree  the  effectiveness  of  the  rays;  whilst  the  liability  to  cracking 
of  the  quartz,  owing  to  the  high  temperature  of  the  lamp,  and 


WATER  57 

the  coldness  of  the  water  passing  over  it,  adds  considerably  to 
the  cost  of  upkeep  of  the  installation. 

In  recent  installations,  the  apparatus  has  been  so  constructed 
as  to  provide  that  the  water,  while  passing  as  close  as  possible 
to  the  lamp,  shall  be  separated  from  it  by  an  air  space.  The 
amount  of  ultra-violet  ray  radiation  in  this  improved  apparatus 
is  ten  times  as  great  as  in  a  lamp  immersed  in  water. 

The  Purification  of  the  Water  of  Swimming  Baths. — The  water 
of  swimming  baths,  which  are  frequented  daily  by  many  bathers, 
becomes  highly  charged  with  bacterial  organisms  derived  from 
the  bodies  of  the  bathers.  Organisms  are  present  which  are 
derived  from  the  mouth,  nose,  and  throat,  and  also  from  the 
intestinal  and  urinary  tracts.  When  highly  diluted  and  inter- 
mixed with  large  volumes  of  clean  water,  these  possibly  harmful 
organisms,  even  when  swallowed  by  bathers,  are  probably  too 
few  in  number  to  originate  disease.  Still,  infection  may  at  times 
occur,  when  the  bath  has  been  used  by  persons  in  an  infective 
condition;  and  it  is  important  that  swimming  should  at  all 
times  be  carried  on  under  conditions  as  Httle  likely  to  favour 
the  transmission  of  infection  as  possible. 

The  simplest  method  of  putting  this  in  practice  is  to  change 
the  water  frequently — daily,  if  possible;  but  this  usually  involves 
a  heavy  cost.  Continuous  aeration  and  filtration  plants  for 
swimming  baths  have  been  devised,  by  which  the  used  water 
can  be  submitted  to  a  certain  amount  of  purification,  and  so 
prevent  the  necessity  for  constant  change  of  water. 

A  Committee  of  the  Royal  Sanitary  Institute  (February,  1913) 
investigated  this  matter,  and  reported  that  such  plants  are 
effective  to  a  certain  extent  in  preventing  the  higher  grades  of 
bacterial  pollution,  and  in  maintaining  the  water  fairly  clear 
and  free  from  odour.  The  water  is  not,  however,  sterilized, 
nor  is  it  kept  free  from  the  slimy  matters  which  tend  to  accu- 
mulate on  the  walls  and  floors  of  the  bath.  On  the  other  hand, 
by  the  addition  of  "  electrolytic  fluid  "  (a  very  weak  solution  of 
hypochlorite  of  magnesium,  prepared  by  the  electrolysis  of 
water  containing  certain  definite  proportions  of  sodium  and 
magnesium  chloride)  to  the  bath  water  in  amount  sufficient  to 
give  one  part  of  free  chlorine  to  every  one  or  two  million  parts 
of  water,  not  only  is  the  water  sterilized,  but  it  is  kept  sweet 
and  free  from  odour,  and  there  is  no  tendency  to  the  deposition 
of  slimy  sediments.  Chlorinated  disinfectants,  containing  definite 
proportions  of  free  or  available  chlorine,  may  be  used  instead  of 


58  HYGIENE    AND    PUBLIC   HEALTH 

"  electrolytic  fluid,"  which  involves  the  installation  of  a  generating 
plant. 

Domestic  Purification.  —  Distillation  effects  a  more  complete 
purification  of  water  than  any  other  method  which  is  practised. 
If  the  first  portions  of  the  distillate,  containing  volatile  sub- 
stances present  in  the  water  to  be  distilled,  are  rejected,  a  water 
free  from  all  foreign  ingredients  is  obtained.  Its  aeration,  how- 
ever, is  deficient ;  but  this  aerated  quality  can  easily  be  furnished 
by  allowing  the  water  to  flow  out  of  fine  holes  in  the  bottom  of  a 
receptacle  and  to  pass  through  the  air  in  finely  divided  streams. 
The  distillation  of  sea  water  is  now  largely  carried  out  on  board 
the  ships  of  H.M.  Navy  and  in  the  large  steamships  of  the  mer- 
cantile marine.  As  long  as  there  is  fuel  on  board,  a  most  whole- 
some water  can  be  obtained.  Distilled  water  acts  very  readily  on 
metals  such  as  copper,  zinc,  iron,  and  lead;  so  it  is  important 
that  the  several  parts  of  the  distillation  or  condensing  apparatus 
should  not  expose  these  metals  to  the  action  of  the  water.  Silver- 
lined  or  block-tin  vessels  and  pipes  may  be  used.  There  are  now 
several  makes  of  small  domestic  stills  upon  the  market. 

By  boiling  water,  carbonic  acid  is  driven  off  with  other  volatile 
gases  dissolved  in  the  water,  and  chalk  (temporary  hardness)  is 
deposited  at  the  bottom  of  the  vessel.  The  water  is  therefore 
softened.  We  have  the  strongest  reason  for  believing  that 
distillation  and  boiling — ^raising  the  temperature  of  the  water 
to  212°  F. — render  innocuous  all  organized  living  matter  in  the 
water.  There  can  be  little  doubt  but  that  the  germs  of  cholera, 
enteric  fever,  and  of  other  diseases,  occasionally  propagated  by 
means  of  impure  drinking  water,  are  effectually  destroyed  by 
even  a  few  minutes'  boiling.  The  spores  that  resist  the  tem- 
perature of  boiling  water  are,  seemingly,  not  disease  germs,  Init 
merely  the  immature  forms  of  harmless  species;  for  experience 
has  shown  that  water,  and  other  fluids  mixed  with  water,  such 
as  milk,  in  which  the  existence  of  germs  capable  of  producing 
enteric  fever,  cholera,  scarlet  fever,  or  diphtheria,  was  almost  un- 
doubted, have  been  rendered  harmless  by  a  few  minutes'  boiling. 

But  to  sterilize  completely  water  or  any  other  fluid,  it  is 
necessary  to  boil  it,  or  merely  raise  the  fluid  to  a  temperature 
of  212°  F.  without  actual  ebulHtion,  for  a  short  period  (half  an 
hour)  on  three  or  four  successive  days.  In  this  way  the  spores 
which  escape  destruction  by  the  first  boiling,  have  time  to  develop 
into  adult  bacteria,  which  are  destroyed  by  the  next  boiling, 
and  so  on,  until  all  the  successive  crops  are  disposed  of.     Boiled 


WATER  59 

water  is  flat  and  insipid,  and  should  be  aerated  before  being 
drunk. 

The  Waterhouse-Forbes  is  perhaps  the  simplest  form  of  port- 
able apparatus  for  boiling  drinking  water,  such  as  is  required  for 
the  use  of  armies  in  the  field. 

Various  schemes  have  been  suggested  for  purifying  ivater  by 
chemical  means.  If  such  a  method  were  easily  practicable,  it 
would  be  of  great  value  for  military  purposes  to  meet  the  require- 
ments of  troops  on  the  march,  or  in  the  field,  when  the  adequate 
filtration  or  sterilization  of  sufficient  water  for  drinking  purposes 
is  a  matter  of  great  difftculty.  Schumberg's  bromine  process 
consists  in  adding  o-o6  grain  of  free  bromine,  dissolved  in 
potassium  bromide,  to  every  litre  of  water,  and  then  after 
5  to  10  minutes  removing  the  excess  of  bromine  and  making 
palatable  by  sodium  sulphite  and  carbonate.  The  addition  of 
calcium  peroxide,  of  ozone,  and  of  potassium  permanganate,  have 
been  suggested  by  other  authorities,  but  have  been  little  em- 
ployed. Chlorine  in  the  form  of  a  hypochlorite,  or  as  hypo- 
chlorous  acid  obtained  by  the  electrolytic  treatment  of  salt  water, 
is  also  serviceable  for  the  above-mentioned  purposes.  Bleaching 
powder  has  also  been  employed  for  the  purpose  of  sterilizing 
water.  When  this  powder  is  added  to  water  the  hypochlorite 
of  calcium  which  is  liberated  is  acted  upon  by  carbonic  acid,  and 
splits  up  into  carbonate  of  calcium  and  hypochlorous  acid,  the 
latter  being  a  powerful  oxidizing  agent.  Ozone  is  more  ex- 
pensive and  difficult  to  employ  than  chlorine,  and  organic  matter 
in  water  may  give  rise  to  an  unpleasant  odour  after  the  use  of 
either  of  these  sterilizing  agents. 

The  use  of  acid  sodium  bisulphate  has  been  recommended  by 
Parkes  and  Rideal  in  the  proportion  of  one  gramme  of  the  salt  to 
a  pint  of  water,  experiment  having  shown  that  in  this  strength,  if 
contact  is  permitted  for  fifteen  minutes,  bacillus  typhosus  infection 
in  broth  culture  medium  is  destroyed.  In  Nesfield's  method  a 
2-grain  tablet  of  iodide-iodate  of  soda  and  a  similar  amount  of 
citric  acid  are  added  to  4  gallons  of  water,  the  effect  being  to  kill  in 
a  few  minutes  any  typhoid  and  cholera  organisms  that  are  present. 
Sabsequently  the  free  iodine  may  be  eliminated  by  a  tablet  of 
sodium  hyposulphite.  The  poisonous  effect  of  copper  upon  the 
lower  forms  of  life  has  led  to  its  advocacy  and  adoption  for  the 
purpose  of  removing  certain  growths  which  form  odour  in 
stagnant  water,  and  also  specific  micro-organisms.  There  is, 
for  instance,  testimony  to  the  fact  that  the  addition  of  10  pounds 


60  HYGIENE    AND    PUBLIC   HEALTH 

of  sulphate  of  copper  to  1,000,000  gallons  of  water  was  suffi- 
cient to  remove  a  fishy  odour  which  was  previously  in  the  water. 
There  is  also  evidence  that  the  addition  of  sulphate  of  copper, 
in  the  proportion  of  i  part  to  100,000  parts  of  water,  will  destroy 
the  typhoid  bacillus ;  but  there  is  conflict  of  opinion  as  to  whether 
this  is  always  effective  in  24  hours.  Strips  of  copper  foil  im- 
mersed in  water  for  12  hours  will  generally  destroy  the  typhoid 
bacillus;  and  this  is  also  true  of  the  storage  of  water  in  copper 
vessels.  In  many  waters  most  of  the  copper  is  deposited  in  an 
insoluble  form ;  but  before  this  method  of  treating  water  can  be 
safely  advocated  it  is  necessary  to  study  the  further  effects  of 
very  small  quantities  of  this  metal  upon  the  more  susceptible 
human  beings. 

Alum  is  sometimes  employed  as  a  purifying  agent.  It  is  much 
used  in  China,  where  the  turbid  waters  of  the  large  rivers  are 
extensively  drunk  after  the  addition  of  a  little  alum.  When 
added  to  water  containing  chalk  in  solution,  it  forms  a  bulky 
precipitate  of  aluminium  hydrate,  which  falls  to  the  bottom, 
carrying  with  it  suspended  and  floating  matters.  It  has  little  or  no 
effect  on  organic  matters  in  solution  in  the  water.  About  6  grains 
of  alum  to  the  gallon  of  water  is  the  proportion  generally  required. 

Filters. — ^Domestic  filters  are  probably  more  often  a  source  of 
pollution  of  the  water  than  otherwise.  It  is  usually  considered 
that  a  filter  requires  no  attention;  it  is  consequently  but  rarely 
cleaned;  the  filtering  material  is  seldom  renewed,  and  its  pores 
become  clogged  with  putrescible  organic  matters,  which  form  a 
suitable  nidus  for  the  growth  and  development  of  living  organisms 
which  contaminate  the  filtered  water.  It  is  not  unusual,  under 
such  circumstances,  to  find  a  considerably  larger  proportion  of 
organic  matter  in  the  filtered  water  than  was  present  before 
filtration. 

This  is  especially  the  case  when  animal  charcoal  is  used  as  the 
filtering  material.  This  substance  is  prepared  by  calcining 
crushed  bones  in  closed  vessels;  it  is  extremely  porous,  and 
exerts  considerable  oxidizing  action  on  dissolved  organic  matters 
in  water,  and  bleaches  colouring  matters  in  solution.  These 
properties,  however,  are  evanescent,  and  rapidly  disappear  if  the 
charcoal  is  not  cleaned  or  renewed,  especially  if  the  water  filtered 
through  it  is  somewhat  impure.  Not  only  this,  but  the  charcoal 
yields  to  water  phosphate  of  lime,  of  which  it  is  largely  composed. 
The  phosphate  favours  the  growth  of  living  organisms,  so  that 
water  must  neither  be  kept  too  long  in  the  filter,  nor  should  it 


WATER  6l 

be  stored  for  use  after  filtration.  Animal  charcoal  does  not 
prevent  the  passage  of  living  disease  germs  through  its  sub- 
stance. For  these  reasons  filters  composed  of  animal  charcoal, 
whether  in  loose  fragments  or  in  compressed  blocks,  are  not  at 
all  suited  for  domestic  use.  They  require  more  care  and  atten- 
tion than  any  domestic  filter  is  likely  to  meet  with.  Charcoal 
block  filters  have  the  power  of  removing  lead  from  water  if  their 
surfaces  are  kept  constantly  clean  by  frequent  scrubbings;  this 
is  probably  due  to  the  lead  forming  a  phosphate  in  the  filter. 

Silicated  carbon  and  manganous  carbon  block  filters  are  fre- 
quently used.  They  consist  of  animal  charcoal  compressed  into 
blocks  by  admixture  with  silica  or  manganese.  They  do  not 
yield  so  much  phosphate  of  lime  to  water  as  the  pure  animal 
charcoal  filters,  but  they  tend  to  become  coated  with  a  layer  of 
organic  matter  which  clogs  the  pores.  The  block  should  be 
brushed  occasionally  to  remove  the  thin  film  coating  it ;  and  every 
three  months,  at  least,  it  should  be  purified  by  subjecting  it  to  a 
red  heat,  or  by  boiling  it  in  a  solution  of  Condy's  fluid  and  sul- 
phuric acid.  Maignen's  Filire  Rapide  consists  of  a  strainer  of 
asbestos  cloth  spread  over  a  perforated  porcelain  cone.  Powdered 
animal  charcoal,  or  other  filtering  medium,  is  laid  over  the 
strainer.  The  delivery  of  water  through  this  filter  is  very  rapid, 
and  the  asbestos  and  powder  can  be  easily  renewed  at  a  very 
small  cost. 

Domestic  filters  are  also  made  of  spongy  iron,  magnetic  carbide 
of  iron,  polarite,  and  carferal,  this  latter  substance  being  a  mixture 
of  iron,  charcoal,  and  clay.  It  has  good  oxidizing  properties, 
and  yields  nothing  to  water  which  is  favourable  to  organic  life; 
but  its  lasting  powers  are  inferior  to  spongy  iron  and  magnetic 
oxide  and  carbide. 

In  Bischoff's  spongy  iron  filter  the  iron  ore  rests  upon  a  layer 
of  pyrolusite  (a  crude  oxide  of  manganese)  above,  and  a  layer  of 
fine  sand  below.  The  pyrolusite  acts  as  an  oxidizer,  and  helps 
with  the  sand  to  remove  the  iron  taken  up  by  the  water.  The 
outlet  to  the  filtered  water  receptacle  is  generally  protected  by  a 
layer  of  asbestos  cloth. 

Filters  of  the  kind  alluded  to  above  may  be  required  to  cleanse 
a  dirty  water,  or  to  prepare  a  water  with  fine  suspended  matter 
in  it  for  passage  through  a  germ  filter;  but  they  afford  no  pro- 
tection against  the  infection  of  water-borne  disease.  Drs. 
Woodhead  and  Wood  point  out  that  they  may  materially 
increase  the  risk  to  the  consumer  of  acquiring  such  infective 


62  HYGIENE    AND    PUBLIC  HEALTH 

diseases,  inasmuch  as  the  specific  organisms  of  these  diseases 
become  arrested  in  the  filtering  materials,  and  may  then  be 
washed  through  in  great  numbers  into  the  filtered  water  for  many 
days  subsequent  to  the  introduction  of  infected  water  into  the 
filter.  If,  for  instance,  the  water  supply  of  a  house  received  a 
chance  contamination,  which  rendered  it  dangerous  for  one  day 
only,  the  consumption  of  the  water  involves  the  risk  of  specific  in- 
fection on  that  day  only ;  but  should  the  polluted  water  be  passed 
through  a  domestic  filter  of  the  kind  indicated,  the  arrest  of  the 
specific  microbes  in  the  filter,  and  their  subsequent  passage  into 
the  filtrate,  would  render  the  water  passed  through  the  filter  liable 
to  convey  infection  for  several  days  after  the  initial  introduction 
of  the  pollution.  The  consequent  multiplication  of  the  oppor- 
tunities of  infection  necessarily  greatly  increases  the  risk  of  such 
an  occurrence.  The  wrong  and  misleading  statements  set  forth 
so  prominently  by  the  makers  of  such  filters,  as  to  their  capacity 
to  render  any  water,  however  polluted,  harmless  and  innocuous, 
gave  rise  to  a  false  sense  of  security  in  the  minds  of  the  public, 
and  are  an  evil  which  should  be  strenuously  combated. 

In  the  Pasteitr-Chamherland  filter  the  water,  under  pressure, 
is  passed  through  hollow  cylinders  of  a  specially  prepared  form 
of  porous  porcelain.  The  filtered  water  is  entirely  free  from  all 
suspended  matters,  including  all  kinds  of  organisms  and  their 
spores.  The  water  is  therefore  sterilized;  but,  the  filter  acting 
merely  mechanically,  there  is  no  alteration  in  the  chemical  com- 
position of  the  dissolved  constituents  of  the  water.  This  filter 
is  employed  to  sterilize  pure  waters  for  laboratory  purposes,  and 
may  with  advantage  be  so  used  for  domestic  purposes.  The 
bottom  of  the  filter  is  connected  with  a  main  under  pressure,  the 
water  issuing  from  the  top.  These  filters  require  periodical  clean- 
ing  at  short  intervals  by  a  hard  brush,  to  remove  slimy  deposits 
on  the  surface  of  the  porcelain;  if  this  is  not  done,  the  delivery 
of  water  becomes  very  much  reduced,  and  separated  organisms 
may  in  time  grow  through  the  cylinders. 

The  Berkefeld  filter  is  similar  in  principle  to  the  above,  but 
the  hollow  cyhnder,  through  which  the  water  is  filtered,  is 
composed  of  a  compressed  siliceous  or  diatomaceous  earth 
called  Kiesselguhr  (fig.  ii).  It  permits  of  more  perfect  cleansing, 
and  is  very  much  more  rapid  in  its  delivery,  but  is  more  fragile 
than  the  Pasteur-Chamberland  filter. 

The  experiments  of  Urs.  Woodhead  and  Wood  show  that 
the    Berkefeld   table   filter   completely   arrests   specific   disease 


WATER  63 

organisms,  but  that,  like  the  Pasteur-Chamberland,  the  Slack 
and  Brownlow,  and  the  Porcclaine  D'Amiante  to  a  lesser  degree, 
it  allows  water  organisms  usually  present  in  water  to  grow 
through  the  filtering  material,  with  the  result  that  they  appear 
in  the  filtrate  on  the  third  day  after  introduction.  It  does  not, 
therefore,  continuously  sterihze.  The  Porcelaine  D'Amiante 
filter,  in  which  the  clay  is  mixed  with  finely  powdered  asbestos, 
is  the  best  sterilizer,  but  in  it 
the  rate  of  filtration  is  so  slow 
that  it  is  unfitted  for  domestic 
purposes. 

The  experiments  conducted 
by  Dr.  Horrocks  at  Netley  in 
1901  show,  (i)  that  typhoid 
bacilli  are  not  able  to  grow 
through  the  walls  of  the  Pasteur- 
Chamberland  candle;  and  the 
filter  ought  to  give  complete  pro- 
tection from  waterborne  enteric 
fever.  (2)  Typhoid  bacilli  can 
grow  through  the  walls  of  the 
Berkefeld  candles,  probably 
owing  to  the  larger  size  of  the 
lacunar  spaces,  and  the  conse- 
quently diminished  immobilizing 
and  devitalizing  influences.  The 
time  required  for  the  typhoid 
bacilli  to  traverse  a  candle  varies 
between  4  and  11  days,  and 
appears  to  be  largely  dependent 
on  the  nutriment  supplied  to 
the  organisms  by  the  medium 
in  which  they  exist.  In  order 
to  obtain  complete  protection 
from  waterborne  enteric  fever,  when  employing  Berkefeld  filters, 
it  is  necessary  to  sterilize  the  candles  in  boiling  water  every 
third  day. 

It  is  obvious  that  the  matters  of  which  this  class  of  filters  are 
composed  must  be  quite  free  from  flaws,  otherwise  a  direct  passage 
of  micro-organisms  will  take  place.  There  is  also  a  certain 
amount  of  lialiility  to  failure  owing  to  hidden  defects  m  the  con- 
nection made  between  the  sterilizing  candle  and  the  delivery  pipe. 


Fig.   II. — Berkefeld  Filter. 

AA,  screws  for  joint  to  open  filter 
case  for  removing  filtering  cylin- 
der for  cleaning,  etc. ;  E,  outlet 
for  filtered  water,  which  can 
either  be  fixed  or  simply  placed 
on  the  protruding  metal  end  of 
the  cylinder  ;  CC,  filtering  cylin- 
der; D,  tap  union  to  attach  to 
water  service ;  F,  flushing  tap 
to  wash  out  filter  or  to  supply 
unfiltered  water. 


64  HYGIENE   AND   PUBLIC   HEALTH 

Sometimes  the  only  water  available  for  drinking,  in  addition  to 
the  risk  of  its  being  specifically  infected,  also  contains  much  sus- 
pended matter.  It  is  useless  to  attempt  to  filter  such  a  water 
through  porcelain,  as  the  filtering  material  soon  becomes  clogged. 
The  Brownlow  germ  filter,  in  which  the  water  is  first  passed 
through  charcoal,  and  then  through  porous  porcelain,  is  specially 
advantageous  in  such  cases;  or  the  porcelain  may  be  covered 
with  a  strainer  of  fine  linen  cloth,  which  can  easily  be  renewed. 

Filters  should  never  be  placed  inside  cisterns.  In  such  posi- 
tions they  are  neglected,  their  very  existence  being  sometimes 
forgotten,  with  the  result  that  they  become  excessively  foul  and 
pollute  the  water  they  are  intended  to  purify. 

From  what  has  already  been  said,  it  will  be  seen  that  the 
essentials  of  a  good  filter  are — that  every  part  should  be  easily 
accessible  for  cleansing  purposes;  that  there  should  be  nothing 
in  the  construction  of  the  filter  which  is  capable  of  yielding 
metallic  or  other  impurities  to  the  water;  that  the  filtering 
medium  should  be  efficient  for  the  work  in  hand,  and  its  purifying 
power  reasonably  lasting;  and  that  the  delivery  of  filtered  water 
should  be  reasonably  rapid. 

Diseases  produced  by  Impure  Water. 

Dyspepsia  and  Diarrhoea. — ^Waters  with  permanent  hardness 
exceeding  8°  or  9°  sometimes  cause  dyspeptic  symptoms  and 
diarrhoea,  especiaUy  amongst  those  who  are  not  used  to  them. 
Similar  symptoms  are  generally  produced  by  drinking  brackish 
water  drawn  from  wells  near  the  sea  coast.  The  injurious  salts 
are  especially  the  sulphates  of  magnesium,  calcium  and  sodium, 
and  the  chloride  of  magnesium.  Particles  of  suspended  clay, 
mica,  or  vegetable  matter  may  also  cause  diarrhoea. 

Waters  containing  calcium  carbonate  in  solution,  the  tem- 
porarily hard  waters,  are  not  in  any  way  injurious  to  health.  At 
the  same  time  there  is  no  reason  to  believe  that  the  chalk  waters 
are  at  all  superior  to  soft  waters  for  drinking.  The  idea  once 
entertained,  that  the  salts  in  hard  water  aided  the  growth  and 
nutrition  of  the  bones  in  children,  has  been  abandoned  as 
untenable. 

Diarrhoea,  often  of  a  severe  choleraic  type  with  violent  purging, 
vomiting  and  cramps,  is  occasionally  produced  by  drinking 
water  contaminated  with  sewage.  But  here,  again,  it  is  princi- 
pally amongst  those  who  are  unaccustomed  to  the  water  that 


WATER  65 

these  severe  symptoms  occur;  or  when  the  water,  previously 
fairly  pure,  becomes  temporarily  polluted,  and  especially  in  the 
summer  months.  Instances  have  been  known  where  people 
have  gone  on  drinking  filthily  polluted  shallow-well  water  for 
years  with  no  apparent  bad  effects.  It  seems,  indeed,  certain 
that  by  long  habitude  the  system  becomes  tolerant  of  many 
substances  in  water  which  exert  a  marked  effect  on  those  who 
drink  them  for  the  first  time.  Whether  the  choleraic  diarrhoea 
is  due  to  the  presence  of  a  Hving  germ  in  the  water,  to  faecal 
organic  matter  in  solution  or  suspension,  or  to  alkaloidal  poisons, 
the  products  of  the  growth  of  bacterial  organisms,  is  not  yet 
certain. 

Vegetable  matter,  such  as  peat  in  water,  is  generally  harmless. 
Large  excess  of  such  matters,  especially  when  decaying,  may 
produce  unpleasant  symptoms. 

Infantile  diarrhoea,  which  is  so  prevalent  and  fatal  in  the 
large  towns  of  this  country  in  the  warmer  summer  months, 
appears  to  be  due  to  water  pollution  in  some  cases. 

The  same  conditions  of  drinking  water  which  produce  diarrhoea 
in  this  country  often  give  rise  to  dysentery  in  hot  climates. 
Dysentery  may  certainly  be  spread  by  the  evacuations  of  patients 
suffering  from  this  disease  contaminating  the  water  used  for 
drinking. 

Enteric  Fever  is  often  spread  by  the  medium  of  water.  There 
is  considerable  evidence  of  the  possibihty  of  the  discharges 
of  a  single  patient  infecting  large  volumes  of  water  {see 
Chapter  IX). 

Asiatic  Cholera  is  a  specific  disease,  spread  by  a  specific  virus 
contained  in  the  evacuations  of  a  person  ill  of  the  disease.  There 
is  now  abundant  evidence  that  cholera  is  often  propagated  by 
means  of  drinking  water  to  which  the  specific  disease  poison  has 
had  access.  This  is  not  the  only  mode  of  spread  of  the  disease, 
any  more  than  it  is  of  enteric  fever;  but  the  evidence  which  is 
constantly  accumulating  points  strongly  to  the  conclusion  that 
as  for  enteric  fever,  so  for  cholera— specifically  infected  drinking 
water  is  one  of  the  most  frequent  methods  of  its  propagation. 

Urinary  calculi  were  at  one  time  supposed  to  arise  from  the 
use  of  hard  water,  but  this  view  is  now  generally  abandoned 
from  want  of  any  definite  proof. 

Rickets  has  been  ascribed  to  the  use  of  soft  water,  but  the 
contention  is  not  warranted  by  facts. 

5 


66  HYGIENE   AND   PUBLIC   HEALTH 

Goitre  appears  to  be  due,  in  many  instances,  to  the  water 
used  for  drinking,  but  the  impurities  in  the  water  which  appear 
to  favour  hypertrophy  of  the  thyroid  gland  in  some  districts  are 
not  those  found  in  the  water  of  other  goitrous  districts.  For 
instance,  the  carbonates  and  sulphates  of  lime  and  magnesia, 
which  are  present  in  the  waters  of  some  districts,  and  have  been 
credited  with  being  the  cause  of  goitre,  are  not  found  in  the 
waters  of  other  districts  where  goitre  prevails.  The  presence  of 
sulphides  of  iron  or  copper  in  water  has  been  regarded  by  some 
observers  as  the  cause  of  goitre,  but  not  apparently  with  much 
reason. 

Major  McCarrison,  I. M.S.  (Milroy  Lectures,  1913),  as  the  result 
of  a  very  exhaustive  investigation  of  the  etiology  of  endemic 
goitre  in  India  and  elsewhere,  is  of  opinion  that  the  essential 
cause  of  the  disease  is  a  micro-organism  that  obtains  admission 
to  the  intestines  of  man,  and  there  creates  a  toxin,  which  so 
influences  the  thyroid  gland  that  it  undergoes  enlargement,  the 
function  of  the  thyroid  being  the  production  of  anti-bodies  or 
antidotes  to  poisonous  products  produced  in  the  living  body  and 
circulating  in  the  blood.  The  special  micro-organism,  as  yet 
unidentified,  appears  to  be  present  in  the  soils  of  goitrous  dis- 
tricts, and  to  be  thence  conveyed  to  man  in  water,  which  passes 
through  or  over  the  goitriginous  soil.  The  ideal  conditions  for 
the  development  of  endemic  goitre  are  stated  by  McCarrison  to 
be  a  country  district  with  an  agricultural  population  living  on  a 
porous  soil,  which  soil  contains  much  organic  matter,  and  which 
by  virtue  of  its  porosity  or  slope  admits  of  the  ready  passage  of 
organic  matter  into  the  unprotected  streams  and  wells  that  are 
the  water  supply  of  the  people.  It  is  in  mountainous  districts 
where  limestone  rocks  abound  that  these  conditions  are  most 
frequently  found  in  combination;  consequently,  goitre  is  pre- 
eminently a  disease  of  the  hills. 

Entozoa. — The  embryos  or  eggs  of  the  following  parasites 
have  been  found  in  water,  and  may  be  taken  into  the  stomach 
of  man  when  such  water  is  used  for  drinking.  They  are: 
Tcenia  solium,  Tcenia  echinococcus,  Bothriocephalus  latiis,  A  scar  is 
Imnbricoides  (round  worms),  Oxyuris  vermicularis  (thread  worms), 
Filaria  sanguinis  hominis  (tropical  endemic  chyluria)  —  the 
embryos  of  which  are  sucked  from  the  blood  of  infected  persons 
by  mosquitoes,  and,  after  developing  in  the  body  of  that  insect, 
are  then  transferred  to  water  by  means  of  the  larvae — Bilharzia 


WATER  67 

hcematobia,  Tricocephalus  dispar,  and  Distoma  hepaticum  (liver 
fluke  of  sheep).  Bilharzia  Jicematobia  causes  endemic  hematuria 
in  Egypt,  Abyssinia,  the  Cape,  etc.  The  ova  are  passed  with 
the  urine,  find  their  way  into  water,  and  hatch  into  cihated 
embryos.  Anchylostoma  duodenale  causes  anaemia,  internal 
haemorrhages,  etc.,  and  occasions  great  mortality  in  Brazil^ 
West  Indies,  and  Egypt,  where  it  is  thought  to  be  sometimes 
due  to  infected  water.  The  embryo  guinea  worm,  Filaria 
draciinculus,  is  aquatic  and  finds  its  way  into  the  human  body 
through  the  alimentary  canal  by  means  of  drinking  water,  the 
adult  worm  being  subsequently  found  in  most  cases  in  the  sub- 
cutaneous tissue  of  the  feet  and  legs  of  affected  persons.  Aquatic 
leeches  may  be  swallowed  in  the  act  of  drinking,  and  fixing  them- 
selves in  the  pharynx  may  cause  much  haemorrhage.  Anthrax, 
hog-cholera,  and  glanders  may  all  be  communicated  to  cattle 
through  the  agency  of  impure  water ;  and  drinking  water  appears 
to  be  the  principal  medium  by  which  the  entozoa  generally  pass 
from  one  animal  to  another. 

Metallic  poisoning  may  be  caused  by  pollution  of  drinking 
water  with  refuse  from  trades  and  drainage  from  metalliferous 
mines,  or  from  absorption  by  water  of  the  metals  used  in  the 
construction  of  distributing  pipes,  tanks,  and  cisterns.  The 
amounts  of  copper,  zinc,  or  arsenic,  which  must  be  present  in 
the  water  to  give  rise  to  symptoms  of  poisoning  have  not  been 
definitely  ascertained;  as  regards  lead,  as  little  as  iV  grain  per 
gallon  may  produce  plumbism  in  predisposed  persons.  In  the 
case  of  the  poisoning  of  Louis  Philippe's  family  at  Claremont, 
I'o  grain  of  lead  was  found  in  each  gallon  of  water. 

The  Collection  of  Samples  of  Water. 

The  water  should  be  sent  to  the  analyst  in  a  stoppered 
Winchester  bottle  of  white  or  pale  green  glass.  The  bottles 
should  be  reserved  for  water  samples,  and  should  be  cleansed 
with  strong  acid,  and  subsequently  well  washed  with  clean 
water,  before  use.  The  bottle  should  be  rinsed  out  twice  with 
some  of  the  water  to  be  examined,  and  should  not  be  entirely  filled 
with  the  sample,  a  small  amount  of  air  being  left  in  it.  The 
bottle  should  then  be  stoppered  and  capped  with  clean  wash- 
leather  or  hnen,  and  dated  and  labelled  to  enable  subsequent 
identification.  Where  the  sample  must  be  taken  by  immersing 
the  bottle,  as  in  ponds,  reservoirs,  rivers,  and  open  wells,  the 


68  HYGIENE   AND    PUBLIC    HEALTH 

bottle  invented  by  Dr.  Thresh,  which  contains  a  contrivance 
wliereby  water  can  be  made  to  enter  the  bottle  at  any  required 
depth  from  the  surface,  finds  a  useful  application. 

The  Opinion  upon  a  Water  Sample. 

Where  the  water  is  considerably  polluted,  no  difficulty  is 
experienced  in  detecting  the  pollution  by  chemical  analysis; 
but,  generally  speaking,  the  shghter  degrees  of  pollution  are 
detected  only  with  difficulty. 

The  most  a  chemical  analysis  of  a  water  can  tell  us  is  whether 
the  figures  of  the  analysis  indicate  little  or  much  organic  im- 
purity as  judged  from  certain  arbitrary  standards.  Whether  the 
sUght  contamination  which  is  practically  always  discovered  is 
harmful,  or  whether  the  particular  water  has  recently  received 
slight  (but  significant  and  maybe  dangerous)  pollution,  can 
only  be  told  with  certainty  by  several  analyses  of  the  water  at 
short  intervals  of  time,  and  a  careful  comparison  of  the  results 
obtained;  or  by  a  comparison  between  the  sample  of  water 
and  others  in  the  immediate  neighbourhood,  collected  from 
similar  sources  from  the  same  geological  area,  and  which  are 
known  to  be  above  suspicion.  A  chemical  analysis,  in  short, 
cannot  always  guarantee  absolute  purity  and  safety,  but  it 
very  frequently  serves  to  reveal  impurity  and  danger. 

Nitrates  and  Nitrites. — These  are  the  oxidized  residues  of 
organic  matters,  almost  always  derived  from  an  animal  source 
(sewage).  Their  determination  is,  therefore,  a  point  of  the 
greatest  importance,  for  they  indicate  either  a  pollution  of  the 
water  at  some  remote  period  with  possibly  dangerous  ingredients, 
or  the  contamination  of  the  water  at  the  present  time  with 
partially  or  completely  purified  sewage.  They  are  found,  often 
in  considerable  quantities,  in  deep  wells  or  spring  waters,  and 
in  this  case  merely  indicate  the  complete  purification  which 
the  water  has  undergone  in  its  passage  from  the  surface  to  the 
subterranean  reservoirs.  In  the  case  of  shallow- well  waters, 
nitrates  and  nitrites,  if  found  in  association  with  excess  of  chlorine 
and  ammonia,  indicate  soakage  of  sewage  or  animal  refuse 
into  the  well,  more  or  less  purified  by  its  passage  through  the 
intervening  layers  of  earth.  At  any  time,  however,  the  purifjdng 
power  of  the  filtering  earth  may  be  exceeded  or  overcome,  and 
then  the  liquid  filth  may  pass  into  the  well  with  its  dangerous 
ingredients    unchanged    or    unpurified.      Nitrates    and    nitrites 


WATER  69 

are  not  present  in  raw  sewage,  but  they  are  found  in  polluted 
streams  and  watercourses,  where  a  certain  amount  of  oxidation 
is  always  in  progress,  and  in  the  effluent  subsoil  waters  from 
manured  or  sewaged  land. 

Ammonia. — The  urea  of  the  urine,  by  a  process  of  fermenta- 
tive decomposition,  rapidly  becomes  carbonate  of  ammonia  in 
sewage.  Ammonia  will  therefore  be  found  in  all  sewage-polluted 
waters,  unless  the  sewage  has  been  filtered  through  a  sufficient 
thickness  of  soil  to  enable  the  bacteria  to  convert  the  ammonia 
by  oxidation  into  nitrates  and  nitrites.  A  few  pure  deep-well 
waters  from  the  greensand  are  found  to  contain  excess  of  ammonia 
owing  to  the  presence  of  a  reducing  salt  of  iron,  which  con- 
verts oxidized  nitrogen  into  ammonia;  but  these  waters  are 
remarkably  free  from  organic  matters.  On  the  other  hand, 
sewage  polluted  shallow-well  waters,  which  contain  excess  of 
ammonia,  often  contain  also  an  excessive  amount  of  organic 
matters. 

Organic  matters  derived  from  an  animal  source  are  dangerous 
as  well  as  disgusting;  the  slightest  trace  of  such  matters  in  a 
water  should  suffice  to  condemn  it.  Organic  matters  derived 
from  the  vegetable  world,  though  often  quite  harmless,  as  when 
they  exist  in  the  form  of  peat,  should  not  be  disregarded;  and 
their  presence  in  considerable  quantity  should  insure  the  rejection 
of  the  water  for  drinking  purposes. 

The  distinction  between  animal  and  vegetable  organic  matters 
in  a  water  is  often  only  made  with  difficulty,  if  at  all.  Generally 
it  may  be  said  that,  when  excess  of  organic  matter  in  a  water 
co-exists  with  excessive  chlorine,  oxidized  nitrogen,  and  am- 
monia, the  source  of  pollution  is  animal  filth  or  sewage.  When,  on 
the  other  hand,  excessive  organic  matter  is  not  accompanied  by 
excessive  chlorine,  oxidized  nitrogen,  and  ammonia,  the  source 
of  pollution  is  probably  vegetable;  and  this  diagnosis  may  be 
confirmed  by  the  results  of  physical  examination  of  the  water, 
and  by  microscopic  examination  of  the  suspended  matters  and 
sediment. 

Inasmuch  as  the  chemical  methods  of  analysis  can  only 
determine  the  presence  and  amount  of  organic  matters  in  water, 
and  cannot  determine  their  quality,  nor  separate  living  and 
possibly  actively  dangerous  organisms  from  dead  and  inactive 
matter,  it  has  been  thought  by  many  that  a  bacterioscopic 
examination  would  afford  conclusive  evidence  of  the  possibly 


70  HYGIENE  AND  PUBLIC  HEALTH 

dangerous  qualities  of  a  water,  and  might  come  in  time  to  super- 
sede chemical  analysis  altogether. 

But  the  characteristic  micro-organisms  of  cholera  and  typhoid 
fever  are  only  with  great  difficulty  isolated  and  separated  from 
the  crowds  of  harmless  species  which  are  found  in  greater  or 
less  abundance  in  all  natural  waters.  The  finding  of  a  greater 
or  less  number  of  non-pathogenic  bacteria  or  fungi  in  a  water 
gives  evidence  of  the  presence  of  a  larger  or  smaller  amount  of 
organic  pollution,  which  forms  a  suitable  pabulum  for  bacteria; 
for  pure  waters  are  found  to  contain  very  few  bacteria  or  fungi, 
whilst  impure  waters  often  swarm  with  them.  They  increase 
in  numbers  if  water  is  stored  for  any  length  of  time. 

The  detection  of  bacteria  of  intestinal  type,  which  have  their 
usual  habitat  in  the  intestines  of  man  and  animals,  throws 
considerable  light  on  the  nature  of  the  pollution,  and  if  they 
are  present  in  such  amount  as  to  point  to  recent  contamination, 
should  serve  to  secure  the  condemnation  of  the  water.  The 
more  important  of  these  intestinal  organisms,  for  which  the 
tests  have  been  most  fully  elaborated,  are  Bacillus  coli  commiims 
and  its  congeners,  Bacilhis  enteritidis  sporogenes,  and  streptococci. 
A  water  which  gives  no  indications  of  the  presence  of  typical 
B.  coli  communis  in  lo  c.c.  of  the  water  examined,  nor  of  strepto- 
cocci in  50  c.c.  (?),  nor  of  the  spores  of  B.  enteritidis  sporogenes 
in  500  c.c.  is,  at  the  time  of  the  examination,  so  free  from  sewage 
pollution  that  it  may  be  certified  as  safe  for  all  domestic  purposes 
providing  its  source  is  satisfactory  (Thresh). 

By  the  typical  B.  coli  communis  is  meant  the  organism  found 
in  animal  excrement  and  in  fresh  sewage.  It  would  appear 
that  in  water  to  which  this  organism  has  obtained  access,  the 
typical  B.  coli  undergo  after  a  time  changes  of  a  degenerative 
character,  so  that  they  no  longer  fulfil  all  the  tests  which  are 
characteristic  of  the  typical  organism.  There  are  also  other 
organisms  of  intestinal  type,  such  as  B.  acidi  lactici  and  B. 
enteritidis  (Gaertner),  which  give  most  of  the  reactions  of  B.  coli, 
but  not  all.  It  is  doubtful,  at  present,  as  to  what  is  the 
precise  significance  of  the  presence  of  such  organisms  in 
water.  Their  presence  certainly  should  lead  to  suspicion  and  to 
further  investigation,  as  they  may  indicate  a  recent  previous 
sewage  contamination,  a  contamination  which  may  also  be  a 
recurring  one. 

The  mere  presence  of   typical  B.  coli  communis  and  of  B. 


WATER 


71 


enteriiidis  sporogenes  in  a  water  would  not  justify,  on  this 
ground  alone,  the  condemnation  of  the  water;  for  they  do  not 
necessarily  indicate  human  contamination.  It  is  only  when 
the  B.  coli  is  appreciably  present  in  i  c.c.  of  the  water  that,  in 
the  opinion  of  many,  the  water  should  be  regarded  as  definitely 
unsafe. 

The  Bacillus  typhosus  is  exceedingly  difficult  to  detect  in 
sewage-polluted  waters.  It  is  very  doubtful  if  this  organism 
has  ever  been  isolated  from  a  natural  water,  even  although  such 
a  water  has  been  credited  with  the  causation  of  enteric  fever. 

In  addition  to  a  chemical  and  biological  examination  of  a 
water  sample,  it  is  of  great  advantage  to  possess  the  fullest 
information  as  to  the  risks  of  pollution  to  which  the  water  has 
been  subjected,  and  this  can  only  be  obtained  from  a  painstaking 
local  investigation. 


Analytical  Results  of  Certain  Waters  (Parts  per  100,000) , 


New 

River 

Company 

(Filtered). 

Polluted 

Well 
Water. 

Peaty 
Surface 
Water. 

Spring 
Water 
from 
Chalk. 

Rain 
Water. 

A  Sus- 
picious 
Water. 

Total  solids 
(a)  Volatile 
ib)  Non-volatile 

31-2 

9-8 
214 

60-0 
25-0 

35-0 

lO-O 
7-0 

3-0 

33-0 
lo-o 

23-0 

3-0 

1-5 

40-0 
15-0 
25-0 

Total  hardness 
{a)  Temporary 
[b)  Permanent 

21-5 

13-0 

8-5 

30-0      !     S'O 
15-0          ro 
15-0          4-0 

26-0 

20 -o 

6-0 

o-S 

O'O 

O-S 
0-25 

25-0 
I4-S 

lo-s 

Chlorine 

1-8 
o-i8 

7-0      i    0-7 

2-5 

4-0 

Oxidized  nitrogen 

o-8o        o-oi 

0-30 

o-oi 

0-50 

o-ooC 
0-012 

01 20 

Free  and  saline  NHg     . 
Organic  NH3 

Oxygen     absorbed     in 
two  hours  at  80°  F. 

O-QOI 
0-003 

0-030  1    o-ooi 
o-ois      0-0I8 

0-00 1 

0-003 

0-015 
0-000 

0-030 

0-l60        0-200 

0030 

0015 

CHAPTER  II 

THE    COLLECTION,  REMOVAL,  AND  DISPOSAL  OF 
EXCRETAL  AND  OTHER  REFUSE 

In  any  community  of  persons,  arrangements  must  be  made 
for  the  collection  and  removal  of  their  excretal  refuse  (faeces 
and  urine),  of  the  waste  waters  from  houses,  and  of  the  dry 
refuse  (ashes,  dust,  and  refuse  food).  The  solid  and  liquid  refuse 
matters  from  stables,  cowsheds  and  slaughter  houses,  street 
sweepings,  and  the  waste  waters  Ifrom  works  and  manufactories, 
must  also  be  removed. 

In  all  towns  the  collection  and  removal  of  dung,  ashes,  dust, 
refuse  food,  and  street  sweepings,  is  performed  by  mechanical 
labour,  the  various  processes  above  mentioned  being  included 
in  the  term  scavenging  ;  whilst  in  some,  human  faeces  and  a 
certain  amount  of  urine  are  also  removed  by  this  method,  after 
being  deposited  in  privies,  cesspools  or  dry  closets,  on  what 
is  known  as  the  conservancy  system.  In  a  large  majority  of 
the  towns  of  this  country,  at  the  present  time,  human  excrement 
is  removed  with  the  liquid  refuse  of  dwellings  on  what  is  known 
as  the  water-carriage  system — a  system  of  drains  and  sewers 
for  the  passage  of  the  refuse  in  a  liquid  condition  to  some  spot 
outside  the  town. 

The  public  health  largely  depends  on  the  efficiency  with  which 
refuse  matters,   and  especially  human  excretal  refuse,  are  re 
moved  from  towns;  for  the  health  of  towns  in  this  country  and 
abroad  has  very  much  improved,  and  the  death  rates  have  been 
permanently  lowered,  as  the  result  of  works  of  sewerage. 

Removal  of  Domestic  Dry  Refuse. 

Domestic  dry  refuse  consists  partly  of  mineral  matters, 
but  to  a  considerable  extent  of  organic  substances  derived  from 
the  waste  scraps  of  food.     These  latter,  being  prone  to  undergo 

72 


DISPOSAL   OF   REFUSE  73 

decomposition  when  stored  in  dust-bins  or  other  receptacles,  are 
very  liable  to  become  a  source  of  nuisance.  It  is,  therefore,  very 
desirable  that  the  quantity  of  organic  refuse  to  be  temporarily 
stored  on  the  house  premises  should  be  reduced  as  far  as  possible ; 
and  this  may  be  accomplished  by  burning  the  more  easily 
destructible  matters,  such  as  potato  peelings  and  other  food 
scraps,  in  the  kitchen  fire  at  the  end  of  every  day. 

The  old-fashioned  brick  dust-bin  is  now  being  largely  replaced 
by  galvanized  iron  receptacles,  with  well-fitting  metallic  covers, 
to  insure  dryness  of  the  contents  and  their  protection  from  rain. 
This  is  an  important  point,  as  the  presence  of  moisture  hastens 
putrefaction  and  the  formation  of  offensive  gases  in  the  refuse. 
The  non-absorbent  walls  of  iron  pails,  and  the  ease  with  which 
they  can  be  moved  and  carried  out  to  the  dust-carts,  constitute 
very  great  advantages  over  the  brick  dust-bins,  of  which  the 
walls  become  saturated  with  decaying  matters  and  the  contents 
are  often  incompletely  removed  at  each  visit  of  the  scavengers. 
The  contents  of  the  dust-bins  or  pails  should  be  removed  at  least 
twice  a  week;  in  summer  a  more  frequent  removal  is  desirable, 
but  is  not  usually  practicable.  Specially  constructed  carts 
provided  with  covers  should  be  employed  to  convey  household 
refuse  through  the  streets.  There  is  an  obvious  advantage  in 
keeping  the  refuse  as  dry  as  possible,  and  if  such  vans  are  not 
provided  with  sUding  metal  covers  or  covers  of  tarpaulin,  the 
escape  of  dust  in  windy  weather  creates  a  great  nuisance.  Motor 
dust  vehicles  are  to  be  recommended  as  effecting  a  great  saving 
of  time. 

Horse  manure  must  also  be  frequently  removed  from  stables, 
and  the  removal  in  urban  districts  is  often  attended  with  con- 
siderable nuisance,  especially  where  peat  moss  litter  is  used  as 
a  bedding  for  the  horses.  The  nuisance  mainly  arises  at  the 
time  of  loading  the  cart,  in  which  the  manure  is  removed,  from 
the  receptacle,  the  disturbance  of  the  contents  of  the  receptacle 
giving  rise  to  very  offensive  gases;  and  the  recently  disturbed 
manure  is  often  highly  offensive  as  it  is  carted  along  public 
thoroughfares.  It  is  found  in  practice  that  the  best  remedy  for 
the  nuisance  is  to  store  the  manure  in  the^same  cart  in  which  it 
is  to  be  removed. 

The  disposal  of  house  refuse  has  hitherto  been  mainly  effected 
by  depositing  it  on  waste  ground,  the  site  being  commonly 
called  a  "  shoot."     These  refuse  heaps  frequently  constitute  a 


74  HYGIENE  AND  PUBLIC  HEALTH 

serious  nuisance  in  the  neighbourhood.  Offensive  gases  are 
given  off  from  the  fermentation  of  the  organic  matters,  and  the 
hquids  draining  from  the  heap  are  of  the  most  noxious  character, 
and  occasionally  cause  serious  pollution  of  neighbouring  water- 
courses. In  windy  weather  dust  and  the  lighter  particles  are 
scattered  around,  whilst  in  summer  the  rotting  refuse  attracts 
large  numbers  of  flies,  which  invade  surrounding  houses  and 
settle  on  food  exposed  to  the  air.  Rats,  too,  burrow  in  the 
heap  in  search  of  food,  and  are  generally  much  complained  of. 
The  practice  of  shooting  or  tipping  refuse  cannot  be  defended, 
and  it  is  slowly  giving  way  to  a  more  sanitary  method,  i.e.,  the 
destruction  of  refuse  by  fire.  As  the  area  of  a  town  increases, 
these  muck-heaps  often  become  the  sites  for  buildings  long 
before  natural  agencies  have  succeeded  in  purifying  the  "  made- 
soil  ";  and,  moreover,  the  difficulty  of  acquiring  sites  sufficiently 
near  the  area  to  be  scavenged  is  growing  greater  year  by  year 
in  our  larger  towns,  and  makes  the  adoption  of  some  other 
method  of  house  refuse  disposal  imperative. 

The  refuse,  when  deposited  at  the  "  shoot,"  is  sometimes 
submitted  to  the  process  of  hand-sorting.  The  paper  and  rags 
are  removed  for  paper-making,  the  tins  and  iron  for  scrap,  the 
bones  for  manure,  the  unbroken  bottles  for  re-use,  and  the 
broken  glass  for  re-melting.  This  sorting  process  is  a  degrading 
occupation;  the  workers  are  of  necessity  in  a  filthy  condition, 
and  the  air  they  breathe  is  constantly  polluted  with  fine  dust 
and  foul  odours. 

The  best  method  of  getting  rid  of  dust-bin  refuse  is  to  burn 
it  in  a  destructor  furnace;  and  offensive  market  refuse,  fish  offal, 
and  even  diseased  carcases  can  also  be  disposed  of  by  this  method 
without  creating  a  nuisance.  The  proportion  of  cinders  in  the 
refuse  is  always  sufficient  to  insure  complete  combustion  in  a  well 
constructed  furnace.  A  small  commercial  value  attaches  to  the 
residual  clinker,  either  for  making  mortar,  or  mixed  with  granite 
chippings  and  cement  to  make  paving  slabs  or  concrete  bricks. 
The  temperature  attained  in  the  furnace,  while  destroying  the 
refuse,  can  be  utilized  to  generate  steam  for  electric  power,  to 
pump  water  or  sewage,  or  to  drive  mortar  mills.  The  calorific 
value  of  the  screened  house  refuse  varies  from  -,V  to  I  that  of 
coal.  In  summer  the  heat  value  of  the  refuse  is  less,  owing 
to  the  smaller  proportion  of  cinders  and  ashes  and  the  greater 
quantity  of  garden  refuse  and  vegctal)le  matter. 


DISPOSAL   OF    REFUSE  75 

There  are  various  types  of  refuse  destructors,  most  of  which 
possess  the  following  features  in  common: — The  furnaces  or 
cells  are  strongly  built  of  brick  with  fire-brick  lining,  and  the 
general  building  is  also  of  brick.  The  destructor  is  approached 
by  an  inclined  roadway  to  the  top  or  tipping  platform,  which  is 
well  above  the  ground  level  In  the  centre  of  this  platform  is  a 
series  of  feeding  holes  or  hoppers  into  which  the  refuse  is  shot, 
and  allowed  to  fall  into  the  cells  below.  The  stokers  rake  the 
refuse  forward  on  to  the  fire ;  and  after  burning,  the  refuse  is  re- 
duced to  about  one-third  or  one-fourth  of  its  original  weight,  the 
residue  consisting  of  fine  ash,  hard  clinker,  etc.  By  means  of 
forced  draught  produced  by  a  steam  jet  or  fans,  the  combustion 
can  be  made  so  complete  that  temperatures  of  1,500  to  2,000°  F. 
are  attainable  merely  from  the  burning  of  the  refuse. 

Some  destructors  are  known  as  "  slow  combustion  "  or  "  low 
temperature "  destructors,  and  in  these  "  fume  cremators " 
should  be  provided  at  the  foot  of  the  chimney.  In  the  fume 
cremator  (which  is  a  coke  furnace)  incompletely  burned  vapours 
and  fine  dust  particles,  which  are  liable  to  escape  into  the  air 
from  the  destructor  furnace,  are  completely  burned  up  before 
they  can  enter  the  chimney- flue.  In  the  "  high  temperature  " 
destructors  such  cremators  are  unnecessary,  and  the  expense  of 
burning  the  coke  or  coke-breeze  in  the  fume  cremator  is  saved. 

The  advantages  of  the  "  low  temperature  "  destructors  consist 
in  the  diminished  wear  and  tear  on  the  fire-brick  sides  of  the 
cells,  and  the  consequent  saving  in  upkeep.  On  the  other  hand, 
the  disadvantages  are  that  both  the  inlet  for  refuse  and  the 
outlet  for  gases  are,  as  a  rule,  at  the  rear  of  the  cell,  and  therefore 
the  empyreumatic  and  noxious  vapours  and  fumes  given  off 
during  the  drying  of  the  refuse,  and  before  it  is  in  active  com- 
bustion, escape  before  being  burnt,  and  a  cremator  is  necessary. 
Further,  more  cells  are  required,  because  a  smaller  quantity  of 
refuse  per  cell  (from  6  to  8  tons)  is  burnt  per  day  than  with 
"  high  temperature  "  destructors.  In  the  "  high  temperature  " 
destructors  (such  as  the  Horsfall  or  the  Beaman  and  Deas)  the 
outlet  for  gases  is  at  the  front  of  the  cell,  and  the  vapours  given 
off  during  the  process  of  burning  and  drying  pass  over  the 
hottest  part  of  the  fire  to  reach  the  exit.  As  the  cell  is  raised  to 
a  very  high  temperature  by  forced  draught  (steam  blast  or  fans) , 
such  gases  are  destroyed  within  the  cell  itself ;  a  largef  quantity 
of  refuse  is  burnt  per  day  per  cell  [i.e.   from  10  to  16  tons),  and 


76  HYGIENE    AND    PUBLIC   HEALTH 

fewer  cells  are  therefore  required.  On  the  other  hand,  they  cost 
more  for  maintenance. 

The  site  on  which  the  destructor  is  placed  should  be  a  central 
one  for  the  district  to  be  served,  or  the  cost  for  cartage  may 
considerably  exceed  that  for  burning;  and  in  some  cases  it  would 
appear  advisable  to  construct  two  destructors  in  different  parts 
of  a  large  town. 

The  number  of  cells  or  furnaces  required  will  of  course  depend 
on  the  nature  and  amount  of  the  refuse  to  be  destroyed,  and 
also  upon  the  type  of  cell  adopted.  If  a  "  high  temperature  " 
destructor  is  selected,  about  ten  cells  are  necessary  for  a  popula- 
tion of  100,000.  These  cells  can  be  erected  in  a  single  row  or 
"  back  to  back."  The  cost  of  erection  may  be  taken  as  about 
£S^o  per  cell,  including  enclosing  building;  and  the  burning  will 
cost  from  gd.  to  2s.  6d.  per  ton,  according  to  the  greater  or  less 
completeness  of  combustion  required,  and  the  number  of  tons 
to  be  burnt  per  cell  per  day. 

Human  Excreta. 

An  adult  male,  living  on  a  mixed  diet  of  animal  and  vegetable 
food,  passes  daily  4  ounces,  by  weight,  of  solid,  and  50  fluid 
ounces  of  liquid  excreta.  The  solid  excreta  of  children  under 
twelve  years  of  age  are  in  amount  considerably  less,  probably 
on  an  average  not  much  more  than  one-half  the  above  quantities. 
If  all  ages  and  both  sexes  are  considered,  the  daily  amount  of 
excreta  per  head  of  a  mixed  population  may  be  taken  at  2|  ounces 
of  faeces,  and  40  fluid  ounces  of  urine.  Fresh  faeces  contain  on 
the  average  23-4  per  cent,  of  dry  solids,  and  fresh  urine  contains 
4-2  per  cent,  (of  which  54  per  cent,  is  urea). 

The  quantity  of  nitrogen  voided  per  head  daily  in  the  excreta 
of  a  mixed  population  is  189  grains  in  the  urine  and  about 
40  grains  in  the  faeces,  making  a  total  of  about  230  grains.  The 
other  valuable  constituents  of  the  excreta  are  phosphates  and 
potash.  A  given  weight  of  faeces  is  more  valuable  than  the  same 
weight  of  urine,  in  the  proportion  of  about  ten  to  six;  but  the 
weight  of  urine  passed  daily  (in  a  mixed  population)  is  about 
sixteen  times  as  great  as  that  of  the  faeces,  consequently  the 
total  urine  is  worth  about  ten  times  as  much  as  the  total  faeces. 

The  estimated  or  theoretical  money  value,  then,  of  the  excretal 
refuse  of  an  individual  of  a  mixed  population  for  one  year  may 
be  taken  as  being  6.";.  8d.  to  7.S.     It  is  very  evident  that  it  must 


DISPOSAL   OF    REFUSE  77 

l)c  impossible  to  realize  practically  any  such  value,  because  it 
is  impossible  to  collect  the  whole  of  the  urine  and  feeces  free  from 
admixture  with  other  substances,  which  greatly  detract  from 
the  value  l)ecause  they  are  agriculturahy  worthless. 

Fccces  and  urine,  especially  when  mixed,  as  in  cesspools, 
privies,  and  sewers,  rapidly  undergo  putrefactive  changes,  giving 
rise  to  the  formation  of  foetid  gases  (organic  vapours,  sulphur- 
etted hydrogen,  ammonium  sulphide,  etc.).  The  urea — CO(NH2)2 
— of  the  urine  decomposes,  giving  rise  to  carbonate  of  ammonia 
— CO(NH.,),  +  2H20  =  (NH4)2C03— and  so  rapid  is  the  change 
that  it  is  probable  that,  even  in  the  best  sewered  town,  all  the 
urea  of  the  urine  in  the  sewage  has  been  converted  into  ammonia 
before  the  arrival  of  the  sewage  at  the  outfall. 

House  Waste  Waters. 

In  these  are  included  the  waste  waters  from  kitchens,  which 
are  highly  charged  with  decomposable  organic  matters  and 
grease,  and  slop  waters  containing  urine,  soap,  and  the  dirt  from 
the  surface  of  the  body  and  from  clothes.  These  waste  waters, 
when  mixed  with  the  liquid  refuse  or  drainage  of  stables,  cow- 
sheds, and  slaughter  houses,  with  the  washings  from  the  street 
surfaces,  with  the  urine  from  public  urinals,  and  the  waste 
liquors  from  manufactories,  form  the  sewage  of  the  non-water- 
closeted  or  midden  towns.  The  drainage  from  stables  is  very 
rich  in  urine  (one  horse  excretes  about  fifteen  times  as  much  urine 
as  an  adult  man),  and  the  waste  liquors  from  manufactories  are 
often  excessively  foul. 

It  is  not  surprising,  then,  to  find  that  such  sewage  is  often 
quite  as  foul  as  that  of  some  water-closet  towns,  which  contains 
the  solid  human  excreta  as  well.  The  Rivers  Pollution  Com- 
missioners stated  in  their  First  Report  that,  "  for  agricultural 
purposes,  lo  tons  of  average  water-closet  sewage  may,  in  round 
numbers,  be  taken  to  be  equal  to  12  tons  of  average  privy 
sewage " — i.e.,  sewage  of  privy  towns,  where  human  faecal 
matters  are  kept  out  of  the  sewers.  Such  being  the  case,  it  is 
necessary  to  bear  in  mind  that,  in  towns  where  there  are  middens 
or  some  form  of  dry  closet  for  the  collection  of  faecal  matters, 
there  is  also  a  liquid  sewage  to  be  conveyed  away  from  houses 
by  drains  and  from  the  towns  by  sewers,  which  is  too  impure  to 
be  admitted  into  a  stream  and  which  must  therefore  be  purified 
before  being  discharged. 


78  hygiene  and  public  health 

Conservancy  Systems. 

The  Privy  or  Midden  System. — The  system  which  formerly 
prevailed  in  many  towns  in  this  country — where  there  was  any 
system  at  all — was  that  of  privies,  midden  pits,  and  cesspools, 
often  open  to  the  air  and  unprotected  from  rain,  and  situated 
in  the  yards  and  areas  about  houses.  These  receptacles  were 
generally  mere  holes  dug  in  the  ground,  and  their  contents  over- 
flowed, saturating  the  air  with  noxious  effluvia,  or  percolated 
into  the  soil  around  and  under  the  houses  and  poisoned  the  water 
in  the  neighbouring  wells. 

At  the  present  time,  in  those  towns  which  still  retain  con- 
servancy systems,  the  middens  are  required  to  be  constructed 
according  to  certain  definite  rules.  The  model  bye-laws  of  the 
Local  Government  Board  with  regard  to  the  construction  of 
privies  and  middens  for  new  buildmgs  require  that  the  privy 
must  be  at  least  6  feet  away  from  any  dwelling,  and  40  or  50  feet 
away  from  any  well,  spring,  or  stream;  means  of  access  must 
be  provided  for  the  scavenger,  so  that  the  filth  need  not  be 
carried  through  a  dwelling;  the  privy  must  be  roofed  to  keep 
out  rain,  and  provided  with  ventilating  openings  as  near  the  top 
as  practicable;  that  part  of  the  floor  of  the  privy  which  is  not 
under  the  seat  must  not  be  less  than  6  inches  above  the  level 
of  the  adjoining  ground,  must  be  flagged  or  paved  with  hard 
tiles,  and  must  have  an  inclination  towards  the  door  of  the  privy 
of  |-  inch  to  the  foot;  the  capacity  of  the  receptacle  under  the 
seat  of  the  privy  must  not  exceed  8  cubic  feet — a  weekly  removal 
is  then  necessary;  the  floor  of  this  receptacle  must  be  in  every 
part  at  least  3  inches  above  the  level  of  the  adjoining  ground; 
the  sides  and  floors  of  this  receptacle  must  be  constructed  of 
impermeable  material — they  may  be  flagged  or  asphalted,  or 
constructed  of  9-inch  brickwork  rendered  in  cement;  the  seat 
may  be  hinged,  or  other  means  of  access  to  the  contents  of  the 
privy  must  be  provided;  and  the  receptacle  must  not  communi- 
cate with  any  drain  or  sewer. 

With  privies  constructed  and  managed  according  to  these 
rules,  there  would  be  no  danger  of  percolation  of  liquid  filth 
into  the  soil  around  houses  and  in  the  neighbourhood  of  wells; 
and  there  would  not  be  much  pollution  of  the  air  from  the 
excreta — except  during  removal — if  dryness  were  insured  by  the 
proper  application  to  them  of  ashes  and  cinders.     The  success  of 


DISPOSAL   OF    REFUSE 


79 


the  system  depends  to  a  large  extent  on  elTicient  insix^ction  l)y 
the  sanitary  inspector,  and  on  proper  scavenging  arrangements. 
Cesspools. — ^These  receptacles  for  filth  are  so  evidently  un- 
desirable in  the  neighbourhood  of  houses  that  it  is  the  practice 
now  in  nearly  all  towns  to  fill  them  in,  and  provide  more  suitable 
means  for  the  collection  of  excreta.  When,  in  the  year  1847,  it 
became  compulsory  to  carry  house  drains  into  sewers,  many 
cesspools  with  which  house  drains  were  connected  were  filled  up, 
or  otherwise  abolished;  but  some  of  them  escaped  observation, 
and  to  the  present  day  occasionally  one  or  more  cesspools  are 


VenlPipe      v. 


j~^  Jnspeclwn 
Cliainber 


ToFimrBed. 


Concrele 


FiG.  12. — Cesspool  with  House  Drain  Inlet  and  Overflow  to 
Filter  Bed. 

discovered  in  the  basements  of  town  houses,  of  the  existence  of 
which  the  owners  or  occupiers  are  ignorant. 

In  country  districts  where  there  are  no  sewers,  cesspools  are 
still  largely  used  for  the  reception  of  human  excreta  and  waste 
waters.  When  dug  in  a  porous  soil,  such  as  gravel  or  chalk, 
they  are  too  frequently  constructed  to  allow  all  the  liquid  filth 
to  percolate  through  their  walls  into  the  soil,  with  the  certain 
danger  of  polluting  wells,  springs,  and  other  sources  of  under- 
ground water-supply.  When  the  liquids  escape  thus  easily,  the 
cesspool  but  very  rarely  requires  emptying,  and  this  fact  con- 
stitutes the  raison  d'Hre  of  the  porous  cesspool. 

The  model  bye-laws  of  the  Local  Government  Board  for  new 


80  HYGIENE   AND    PUBLIC   HEALTH 

buildings  require  that  a  cesspool  must  be  at  least  50  feet  away 
from  a  dwelling,  and  60  to  80  feet  distant  from  a  well,  spring, 
or  stream.  It  must  have  no  communication  with  a  sewer  (in 
sewered  districts) ;  its  walls  and  floor  must  be  constructed  of 
good  brickwork  in  cement,  rendered  inside  with  cement,  and 
with  a  backing  of  at  least  9  inches  of  well  puddled  clay  around 
and  beneath  the  brickwork.  The  top  of  the  cesspool  must  be 
arched  over  and  means  of  ventilation  provided.  Constructed 
in  accordance  with  these  rules,  and  with  the  house  drain  dis- 
connected from  the  cesspool  in  the  same  manner  as  it  is  dis- 
connected from  a  sewer,  the  possible  dangers  of  cesspools  are 
reduced  to  a  minimum. 

In  this  country  cesspools  are  often  emptied  by  hand  labour 
— a  disgusting  and  dangerous  task — or  by  pumping  into  a  night 
soil  cart.  On  the  Continent,  and  especially  in  Paris — where 
so  many  houses  have  a  fosse  permanente  in  the  courtyard — 
the  cesspools  are  emptied  by  pneumatic  pressure.  A  flexible 
tube,  connected  with  a  tub  or  tonneau  exhausted  of  air  by  an  air- 
pump,  is  thrust  down  to  the  bottom  of  the  cesspool.  On  turning 
a  valve,  the  pressure  of  the  atmosphere  forces  the  contents  up 
into  the  tonneau.  The  Bexley  cart,  now  commonly  used  in  this 
country,  is  worked  on  the  same  principle.  This  method  does  not 
give  rise  to  any  nuisance  comparable  with  that  from  emptying 
the  cesspools  by  hand  labour.  Whenever  a  cesspool  or  privy  pit 
ceases  to  be  used,  it  should  be  completely  emptied  and  the  con- 
taminated brickwork,  earth,  etc.,  removed;  or,  after  emptying,  its 
walls  should  be  well  limed,  and  the  interior  filled  up  to  the  ground 
level  with  good  concrete  or  with  dry,  clean  earth  or  brick  rubble. 

The  Pail  System. — -In  this  system  the  excreta  are  received 
into  movable  receptacles,  such  as  pails  and  tubs.  Removal  is 
thereby  greatly  facilitated  and  there  is  no  pollution  of  the  air 
from  disturbance  of  contents,  as  there  always  must  be  when 
the  contents  of  middens  are  taken  away.  In  some  towns  iron 
pails  are  used,  in  others  tarred  oak  pails.  The  capacity  of  the 
pail  should  not  be  greater  than  2  cubic  feet.  Both  kinds  should 
be  provided  with  a  close  fitting  lid,  to  be  adjusted  before  removal 
of  the  pail  by  the  scavenger. 

The  structure  of  the  privy  (fig.  13)  need  only  be  very  simple; 
it  should  be  well  roofed  and  louvred  for  ventilation,  its  floor 
being  raised  above  the  level  of  the  ground  adjoining  and  flagged, 
and  the  pail  placed  under  the  seat.     The  seat  may  be  hinged  to 


DISPOSAL   OF   REFUSE 


8l 


/\ 


insure  a  more  complete  covering  of  the  excreta  with  cinders  and 
ashes,  when  these  are  used,  and  to  allow  of  the  removal  of  the 
pail;  or  the  back  wall  of  the  closet  may  be  provided  with  a  door 
to  facilitate  the  latter  purpose.  The  pail  should  be  removed  at 
no  longer  intervals  than  once  a  week  and  a  clean  one  substituted. 

It  is  very  important,  from  a  sanitary  point  of  view,  that  the 
pail  contents  should  be  kept  as  dry  as  possible;  and  for  this 
object  the  house  ashes  and  cinders  should  be  thrown  into  the 
pail,  either  by  a  scoop  after  each  use  of  the  closet,  or  by  a 
mechanical  arrangement  (to 
be  described  under  earth- 
closets)  above  the  pail, 
which  sifts  the  cinders  and 
deposits  the  fine  ash  auto- 
matically on  the  pail  con- 
tents, as  in  Morell's  closet. 
It  is  perhaps  convenient  for 
sanitary  authorities  to  re- 
move all  house  refuse  in 
one  receptacle;  but  if  it  is 
intended  to  create  a  saleable 
manure  from  the  excretal 
refuse,  all  garbage  and 
kitchen  refuse,  and  even  all 
but  the  very  finest  ash  (for 
this  detracts  from  the  value 
of  the  manure),  should  be 
kept  out  of  the  pails  and 
removed  separately.  In  such 
cases  the  pail  contents  can 
no  longer  be  kept  dry,  and 
sanitary  considerations  are, 
insure  commercial  ends. 

All  slops  should  be  kept  out  of  the  pails,  and  should  be  carried 
away  from  the  houses  in  drains  with  the  other  waste  waters. 
In  some  cases  separation  of  the  urine  from  the  faeces  has  been 
attempted.  Besides  introducing  a  complication  into  a  system 
whose  chief  merit,  perhaps,  is  simplicity,  this  plan  is  open  to  the 
great  objection  of  abstracting  the  most  valuable  fertilizing  con- 
stituents of  the  manure  in  posse. 

In  the  Goux  system  an  attempt  is  made  to  dry  the  excreta  by 


3" 


Fig.  13. 


-Privy  constructed  for 
Pail  System. 


to  a  certain  extent,  sacrificed  to 


82  HYGIENE    AND    PUBLIC   HEALTH 

lining  a  wooden  tub  with  a  \a.yeT  of  refuse  sawdust,  shoddy,  tan, 
or  other  absorlx'nt  material,  to  which  is  added  a  little  soot, 
charcoal,  gypsum,  or  other  cheap  deodorizer.  This  system  was 
in  use  in  Halifax,  and  on  the  whole  has  worked  well. 

Wood  charcoal'  and  charcoal  obtained  from  seaweed  (Stanford's 
patent)  have  been  used  instead  of  ashes  to  aid  in  drying  the  pail 
contents.  They  act  as  absorbents,  and  to  a  certain  extent  as 
deodorizers. 

Manufacture  of  Manure. — In  towns  situated  in  agricultural 
districts,  where  there  is  a  demand  for  the  coarser  sorts  of  manure, 
the  pail  contents  need  merely  be  mixed  with  a  certain  portion  of 
fine  ash.  But  in  some  of  the  large  towns,  where  the  pail  systems 
are  in  vogue,  it  is  now  the  practice  to  convert  the  pail  contents 
into  a  dry  manure  of  a  more  imperishable  character,  which  can 
be  packed  and  sold  at  a  distance.  The  heat  required  for  this 
purpose  is  generated  by  the  combustion  of  house  cinders  and 
refuse  in  a  destructor  furnace,  the  invention  of  Mr,  Fryer. 

The  pail  contents — urine  and  faeces  without  ashes — are  mixed 
with  a  small  portion  of  sulphuric  acid,  to  fix  the  ammonia,  in 
an  air-tight  store  tank,  where  the  thicker  portion  of  the  material 
settles  at  the  bottom.  The  more  fluid  portion  of  the  contents 
of  the  tank  is  drawn  off  into  evaporators,  which  are  tall  cast- 
iron  cylinders  each  containing  near  its  lower  end  a  drum-shaped 
heater,  precisely  resembhng  a  multitubular  steam  boiler.  These 
cylinders  are  partially  filled,  and  the  heating  drums  are  covered 
with  the  thin  liquid ;  steam  is  then  introduced  within  the  heating 
drums,  and  the  liquid  becomes  partially  concentrated. 

When  the  contents  of  these  cylinders  have  lost  by  evaporation 
the  greater  portion  of  their  water,  they  are  drawn  off  into  a 
Firman's  Dryer,  into  which  the  thick  portion  of  the  pail  con- 
tents, which  settled  in  the  store  tank,  has  also  been  admitted. 
This  machine  consists  of  a  steam- jacketed  horizontal  cyhnder, 
traversed  by  a  steam-heated  axis  with  steam-heated  revolving 
arms,  and  furnished  with  scrapers  to  keep  the  inner  surface  of 
the  cylinder  free  from  accumulations  of  dried  excreta.  The 
pail  contents  are  admitted  into  the  dryer  at  a  consistency  of 
thin  mud;  after  treatment  they  emerge  as  a  dry  powder — 
poudrette — resembling  guano  in  appearance  and  quahty.  The 
odorous  gases  given  off  during  the  process  are  all  passed  through 
the  destructor  fire  and  burnt.  From  the  time  the  liquid  material 
enters  the  store  tank  until  the  end  of  the  process  when  it  emerges 


DISPOSAL   OF    REFUSE  83 

as  a  dry  powder,  no  odorous  gases  should  be  permitted  to  escape 
into  the  outer  air,  and  no  nuisance  ought  to  result. 

The  Dry  Earth  System. — This  system,  often  referred  to  as 
Moule's  system,  consists  in  the  appHcation  to  the  excreta, 
deposited  in  a  pail  or  tub,  of  a  certain  quantity  of  dried  and 
sifted  earth.  One  and  a  half  pounds  of  dry  earth  applied  in 
detail,  i.e.,  each  particular  stool  being  covered  at  once  with  this 
quantity,  is  found  to  be  sufficient  to  remove  odour  and  to  form 
a  compost  which  remains  inoffensive  as  long  as  it  is  dry.  A 
certain  action  takes  place  in  the  mixture  of  earth  and  excrement, 
which  results  in  the  complete  disintegration  of  the  faecal  matters 
and  paper,  which  after  a  time  are  found  to  have  completely  dis- 
appeared and  are  no  longer  recognizable.  The  compost  after 
further  drying  may  be  used  over  again,  and  has  the  same  action 
as  the  original  dry  earth.  The  best  kinds  of  earth  are  loamy 
surface  soils,  and  vegetable  mould.  Sand,  gravel,  and  chalk  are 
unsuitable  and  inefficient. 

The  closet  generally  used  with  this  system  is  almost  identical 
with  the  cinder-sifting  ash-closet  previously  mentioned.  There 
is  a  hopper  or  metallic  receptacle  above  and  behind  the  seat, 
and  the  proper  amount  of  dry  earth  is  shot  into  the  pail  by  a 
simple  mechanical  contrivance  connected  with  a  handle,  or 
self-acting  seat  arrangement.  The  contents  of  the  pail  must 
be  kept  as  dry  as  possible,  or  fermentation  results,  with  the 
disengagement  of  foul  gases;  consequently  slops  must  on  no 
account  be  thrown  into  them,  and  even  chamber  urine  must 
be  kept  out  of  them,  unless  a  considerable  extra  quantity  of  dry 
earth  is  used.  The  earth  must  be  dried  before  use,  and  then 
sifted  by  means  of  a  sieve,  the  finer  portions  only  being  used. 

There  can  be  but  little  doubt  that  the  compost  or  manure 
produced  by  the  passage  of  the  earth  even  five  or  six  times 
through  the  closet  has  but  little  agricultural  value.  The  late 
Dr.  Voelcker  estimated  its  value  as  only  ys.  6d.  per  ton.  It  is 
probable  that  there  is  some  escape  or  evolution  of  nitrogen  in 
a  free  state  from  the  manure  when  kept;  and  this  may  partly 
account  for  its  deficiency  in  fertihzing  properties.  But  when 
we  reflect  on  the  large  amount  of  valueless  earth  with  which 
the  compost  is  diluted,  and  the  absence  from  it  of  a  large  pro- 
portion of  the  daily  urine  of  each  individual,  the  reasons  for  its 
low  value  are  not  far  to  seek. 

The  wider  adoption  of  scavenging  schemes  is  a  serious  need 


§4  HYGIENE   AND   PUBLIC   HEALTH 

for  rural  districts,  and  without  them  the  pollution  of  the  shallow 
wells  must  inevitabty  continue. 

A  scavenging  scheme  is  most  urgent  where  the  cottages  are  in 
close  juxtaposition,  and  possess  only  a  very  small  garden  area, 
and  where  the  wells  run  exceptional  risks  of  pollution.  With  a 
very  small  garden  area,  covered  with  a  crop,  the  privy  pit  often 
cannot  be  cleaned  out  until  the  crop  is  taken  out  of  the  ground, 
and  so  pail  closets  requiring  a  weekly  or  twice  weekly  emptying 
are  impracticable  when  there  is  no  scavenging  scheme. 

Such  a  scheme  adopted,  it  becomes  possible  to  abolish  all 
privy  cesspits,  and  to  replace  them  by  pail  closets  on  cemented 
surfaces. 

A  scavenging  cart  should  be  taken  weekly  to  each  dwelhng; 
the  pail  contents  and  the  dry  domestic  refuse  (collected  in 
covered  galvanized  iron  pails)  should  be  removed  and  sanitarily 
disposed  of  by  a  contractor.  The  special  expenses  chargeable  to 
the  parish  are  small  for  this  kind  of  work,  though  they  may  be 
serious,  having  regard  to  the  rateable  value. 

For  emptying  cesspools,  the  scavenging  scheme  should  include 
a  force  pump  and  a  hose,  with  a  solution  of  copperas,  to  be  em- 
ployed when  occasion  demands. 

The  Disposal  of  Slop  Waters. 

We  have  already  seen  that  the  conservancy  systems  do  not 
provide  for  the  removal  of  the  liquid  refuse,  domestic  or  muni- 
cipal; and  we  have  seen,  too,  that  in  the  so-called  midden 
towns  this  liquid  refuse  or  sewage  may  be  quite  as  impure  as  the 
ordinary  sewage  of  some  water-closet  towns.  In  these  towns, 
too,  there  is  always  a  certain  percentage  of  houses  provided 
with  water-closets,  so  that  the  crude  matter  passing  into  the 
sewers  is  inadmissible  into  a  river  or  stream,  and  requires  to  be 
purified.  A  system  of  drains  and  sewers  is  necessary  for  its 
removal  from  the  town ;  and  the  principles  on  which  such  drains 
and  sewers  must  be  constructed  do  not  differ  from  those  which 
would  be  necessary  if  the}/  were  intended  to  carry  water-closet 
sewage  as  well. 

In  small  villages  and  isolated  houses  provided  with  middens 
or  some  form  of  dry  closet,  the  slop  waters  are  usually  carried  by 
a  drain  from  a  sink  or  yard  gully  into  "  sumpt  "  holes  in  the 
garden,  into  an  open  ditch,  into  a  cesspool,  or  into  a  stream; 
if  into  a  "  sumpt  "  hole  or  open  ditch,  there  to  stagnate  and 


DISPOSAL   OF   REFUSE  85 

generate  offensive  gases;  if  into  a  cesspool,  often  to  percolate 
through  its  porous  walls  and  pollute  the  neighbouring  wells; 
and  if  into  a  stream,  to  foul  it  nearly  as  much  as  if  they  contained 
the  solid  excreta  also.  The  slop  waters  may  be  retained  in 
cesspools  which  are  rendered  impermeable  by  brickwork  set  in 
cement  and  well  puddled  with  clay  outside;  and  they  can  then 
be  utihzed  on  garden  ground  by  means  of  a  pump  and  hose  and 
jet.  They  may  also  be  passed  through  a  small  coke  or  ash  filter, 
which  should  be  prepared  on  a  specially  selected  area  well  away 
from  the  house;  or  they  may  be  disposed  of  by  irrigation  upon 
grass  fields. 

Wherever  the  nature  of  the  soil  and  the  slope  of  the  land  will 
permit  of  it,  recourse  may  be  had  to  sub-irrigation  to  purify  the 
dirty  water  and  utiHze  it  to  the  best  advantage.  A  very  small 
piece  of  ground  is  required  for  this  purpose.  The  late  Mr.  Rogers 
Field  considered  4  perches  of  land  sufficient  for  an  ordinary 
cottage.  The  drain  conveying  the  slop  waters  from  the  house 
should  be  connected  by  a  few  lengths  of  impermeable  piping  with 
a  system  of  2-inch  agricultural  porous  earthenware  pipes,  with- 
out joints,  laid  laterally  about  5  or  6  feet  apart,  at  a  depth  of 
about  8  to  12  inches  in  the  soil,  the  whole  having  a  slight  fall  or 
inclination,  away  from  the  house,  of  6  or  8  inches  in  100  feet. 
The  ends  of  the  pipes  should  rest  upon  cradles  formed  of  larger 
half-pipes,  and  similar  covers  should  be  placed  above,  so  as  to 
prevent  earth  getting  into  the  pipes,  whilst  allowing  the  water 
to  escape.  The  end  of  the  main  outlet  pipe  should  turn  up 
into  the  air  to  allow  air  to  escape.  This  is  especially  necessary 
when  the  slop  waters  are  discharged  into  the  sub-irrigation 
drains  by  a  flush  tank. 

If  the  soil  is  very  porous,  no  under-drainage  is  needed ;  other- 
wise, porous  drain  pipes  must  be  laid  at  a  depth  of  about  3  feet 
from  the  surface,  with  an  outlet  into  a  stream  or  ditch.  The 
slop  waters  escape  through  the  open  joints  of  the  sub-irrigation 
pipes  into  the  soil,  where  some  of  their  fertilizing  ingredients  are 
absorbed  by  the  roots  of  the  grasses  and  vegetables  grown  on 
the  plot,  and  the  rest  is  purified  by  percolation  through  the  soil ; 
so  that  the  efiiuent  water  passes  away  in  a  purified  condition 
into  a  stream  or  ditch,  or  helps  to  swell  the  volume  of  the  subsoil 
water. 

The  chief  difficulty  in  connection  with  this  method  is  that  the 
flow  of  slop  waters  from  a  single  house  is  so  small  that  the  liquid 


86 


HYGIENE   AND   PUBLIC   HEALTH 


penetrates  but  a  short  way  along  the  sub-irrigation  pipes,  which 
become  in  time  choked  with  deposit;  and  that  portion  of  the 
sub-irrigation  plot  nearest  the  house  receives  an  unduly  large 
share  of  the  irrigating  hquid,  and  its  cleansing  properties  are 
speedily  overtaxed.  This  difficulty,  where  the  gradients  admit 
of  the  necessary  loss  of  head,  has  been  overcome  by  providing 
a  flush  tank  which  will  discharge  at  intervals  into  the  head 
of  the  system.  The  tank  now  in  most  general  use  for  this 
purpose  is  fitted  with  the  annular  siphon  arrangement  invented 
by  Mr.  Rogers  Field. 

In  the  annular  siphon  tank  (fig.  14)  the  ascending  arm  of  an 
ordinary  siphon  is  represented  by  a  short  wide  cylindrical  pipe, 

closed  at  the  top,  which  is  placed 
over  and  encloses  the  descend- 
ing arm,  a  longer  pipe  of  smaller 
diameter.  The  upper  end  of  the 
descending  arm  is  open,  and  in 
Field's  tank  is  provided  with  a 
lip  projecting  inwards  and  down- 
wards, which  serves  to  direct  the 
water,  as  it  overflows,  into  the 
centre  of  the  pipe.  The  lower  end 
of  the  descending  arm  opens  over 
a  discharging  trough  below  the 
body  of  the  tank,  and  is  trapped 
by  the  water  which  stands  in 
this  trough  to  the  level  of  the  top  of  a  weir,  over  which  the 
water  flows  into  a  pipe  connected  with  the  head  of  the  sub- 
irrigation  system. 

Only  a  very  small  dribble  of  water  into  the  tank  is  necessary 
to  put  the  siphon  into  action.  This  takes  place  as  follows:  As 
the  tank  fills,  the  water  ascends  between  the  inner  and  outer  pipes 
constituting  the  siphon,  until  it  reaches  the  level  of  the  top  of 
the  inner  pipe,  the  air  displaced  finding  an  exit  through  this 
pipe  into  the  discharging  trough  below.  The  water  then  trickles 
over  the  top  of  the  inner  pipe,  and,  thrown  into  its  centre  by  the 
lip,  falls  clear  of  the  sides,  entangling  and  carrying  air  with  it 
which  cannot  pass  back,  owing  to  the  lower  end  of  the  pipe  being 
trapped.  This  continues  until  the  siphon  is  sufficiently  exhausted 
of  air  to  be  brought  into  action,  when  the  whole  contents  are 
discharged  by  siphonage. 


/ 

u 

\ 

::^^g 

s 

^*w 

Fig.  14. — Field's  Annular 
Siphon  Flush  Tank  for 
Flushing  House  Drains. 


DISPOSAL   OF   REFUSE  87 

It  is  not  necessary  to  strain  the  slop  waters  before  they  enter 
the  tank,  as  they  contain  but  few  of  the  coarser  suspended 
matters  and  sohd  particles  found  in  water-closet  sewage.  The 
sub-irrigation  drains  require  to  be  taken  out  of  the  ground,  and 
the  deposit  removed  before  they  are  relaid,  every  few  years, 
according  to  circumstances. 

Comparison  of  Methods. 

There  can  be  no  doubt  that  all  conservancy  systems  proceed 
on  a  wrong  principle,  viz.,  that  of  keeping  excremental  matters 
within  or  near  dwelhngs  longer  than  is  desirable  from  the  point 
of  view  of  health.  In  towns  the  expense  of  scavenging  is  directly 
proportional  to  the  frequency  of  removal,  so  that  there  is  always 
an  inducement  to  the  local  authority  to  economize  at  the  risk 
of  the  health  of  the  inhabitants.  The  costs  of  this  kind  of 
scavenging  are  high,  and  nowhere  does  the  sale  of  the  refuse 
cover  the  expense. 

Movable  receptacles  are  far  better  than  fixed  ones  for  the 
collection  of  excremental  matters.  The  pail  system  is  un- 
doubtedly the  best  for  towns  which  will  not  enforce  the  adoption 
of  water-closets.  In  the  case  of  Nottingham,  where  middens, 
pails,  and  water-closets  are  in  use  in  different  parts  of  the  town, 
Dr.  Boobbyer  has  shown  that  the  greatest  prevalence  of  enteric 
fever  is  to  be  found  in  the  houses  with  middens,  and  the  least 
in  the  water-closeted  houses,  those  with  pails  occupying  an 
intermediate  position. 

However  suitable  the  earth-closet  system  may  be  for  country 
houses  and  villages  in  this  country,  and  for  villages  and  stations 
in  India,  and  in  cold  countries,  where  the  water  supply  is  small 
and  Uable  to  interruptions,  and  where  earth  of  suitable  quality 
is  easily  procured  and  dried,  and  the  compost  can  be  distributed 
over  gardens  and  fields  in  the  immediate  vicinity,  it  is  quite 
inapplicable  to  towns  of  any  size,  on  account  of  the  enormous 
quantities  of  earth  that  would  have  to  be  dried  and  brought 
into  the  town,  the  difficulties  of  storing  the  earth  on  the  premises 
of  houses  and  keeping  it  dry,  and  the  still  larger  quantity  of 
nearly  worthless  manure  to  be  removed  out  of  the  town  and 
finally  disposed  of. 


88  hygiene  and  public  health 

The  Water-Carriage  System. 

In  this  system  the  soUd  excreta  together  with  all  liquid  refuse 
are  conveyed  away — borne  along  by  flowing  water — in  drains 
and  sewers  from  the  neighbourhood  of  houses  and  towns.  In 
many  towns,  before  anj'  general  introduction  of  water-closets, 
sewers  existed  for  conveying  away  house  waste  waters,  stable 
drainage,  surface  and  storm  waters,  and  in  some  cases  waste 
liquors  from  manufactories.  These  sewers,  which  were  made  of 
brick,  oval  or  circular  in  section,  acted  also  as  land  drains;  for 
not  being  constructed  of  impermeable  materials,  they  admitted 
subsoil  water  and  had  considerable  effect  in  drying  the  soil. 

It  became  at  one  time  also  the  practice  to  drain  off  the  hquid 
contents  of  privies  and  middens,  or  to  carry  overflow  pipes  from 
cesspools  into  these  sewers,  which  in  consequence  speedily  became 
choked  with  sediment.  This  sediment  rapidly  putrefied,  and 
the  offensive  gases  given  off  created  an  abominable  nuisance. 
It  then  became  necessary  for  the  sewers  to  be  regularly  cleansed, 
and  the  deposit  had  to  be  removed  at  great  expense  by  hand 
labour.  The  drainage  of  privies  and  middens  entered  the  sewers 
in  a  most  foul  and  offensive  condition,  owing  to  the  putrid  state 
of  the  contents  of  these  receptacles.  Another  result  was  that  the 
streams  and  rivers  into  which  this  sewage  was  permitted  to  pass 
became  highh'  polluted.  In  man}'  towns  these  brick  sewers  still 
exist,  and  perform  the  double  function  of  removing  sewage  and 
rain-water,  and  draining  the  subsoil;  whilst  in  others  they  are 
only  permitted  to  perform  their  original  function  of  carrying  off 
rain  and  surface  water  and  of  draining  the  subsoil,  impermeable 
sewers  being  laid  to  remove  the  sewage  of  the  town  on  what  is 
known  as  the  separate  system. 

House  Drainage  Arrangements. 

Water-closets. — A  water-closet  may  be  defined  as  an  apparatus 
for  the  reception  of  excrement,  which  is  connected  with  a  sewer 
by  a  pipe,  and  in  which  water  must  be  used  to  carry  awa}'  the 
excrement  deposited  in  it.  It  is  therefore  seen  at  once  to  differ 
in  all  essentials  from  a  privy,  which  ought  not  to  be  connected 
in  any  way  with  a  sewer,  and  in  which  water  cannot  properly 
be  used.  Water-closets  may  be  classified  under  two  heads  : 
{a)  those  in  which  there  is  no  movable  apparatus  for  retaining 


DISPOSAL   OF   REFUSE 


89 


water  in  the  basin ;  (6)  those  in  which  there  is  such  a  movable 
apparatus.  Under  the  lirst  head  are  inchided  the  various  types 
of  hopper  closets  ;  under  tlie  second  head,  pan,  valve,  and  plug 
closets. 

The  hopper  closet  consists  of  an  inverted  stoneware  cone, 
connected  below  with  an  LO  or  Lr -shaped  pipe,  which  retains 
sufficient  water  to  prevent  the  free  passage  of  air.  and  is  known 


Fig.  15. — Long  Hopper 
Water-closet  with  Side- 
inlet  FOR  Flushing. 


Fig.    16. 


-Wash-down   Water- 
closet. 


as  a  trap.  The  old  form  of  hopper  closet,  called  the  long  hopper, 
from  the  length  (about  iS  inches)  of  the  cone  (fig.  15),  is  liable  to 
fouHng  of  the  basin,  and  is  difficult  to  flush,  especially  where  the 
water  is  admitted  by  a  side  inlet,  which  has  the  effect  of  causing 
the  water  to  whirl  round  and  round,  whereby  the  trap  is  not 


Fig.  17. — Wash-out  Water-closet. 


flushed  out  and  excreta  are  left  behind.  A  short  hopper  or 
wash-down  (fig.  16)  is  constructed  with  a  shorter  (8  to  9  inches) 
cone  of  china  or  stoneware ;  the  back  of  the  cone  should  be  made 
nearly  vertical,  so  that  the  excrement  drops  into  the  water  of  the 
trap,  and  not  upon  the  sides  of  the  basin.     The  short  hopper. 


go  HYGIENE    AND    PUBLIC    HEALTH 

especially  when  constructed  with  a  "  flushing  rim,"  by  which 
the  sides  of  the  basin  are  well  washed,  is  found,  under  proper 
management,  to  be  easily  kept  clean.  It  is  a  form  of  closet  which 
is  now  largely  used,  for  it  is  simple  in  construction,  inexpensive, 
has  no  confined  air  space  where  foul  air  could  accumulate,  and 
conveys  slop  waters  away  at  once,  no  overflow  pipe  being 
necessary. 

For  the  out-door  water-closets  of  the  houses  of  the  working 
classes  the  short  hopper  closet,  made  in  stout  glazed  stoneware 
or  fireclay,  is  far  the  best.  The  floor  of  the  closet  should  not  be 
of  wood,  but  of  cement-concrete  sloped  towards  the  door  of  the 
closet.  The  siphon  trap  under  the  closet  basin  should  be  fixed 
upon  the  cement  floor  by  embedding  it  in  cement  so  as  to  form 
a  pedestal,  thus  rendering  it  and  the  basin  very  strong  and 
perfectly  secure.  There  should  be  no  vertical  wooden  casing, 
and  the  seat  should  be  hinged,  so  that  every  corner  around  the 
space  beneath  the  seat  can  be  got  at  for  cleansing.  The  trap  of 
the  closet  should  be  joined  at  the  back  of  the  basin  to  a  4-inch 
stoneware  drain  pipe  by  a  cemented  joint.  A  closet  fixed  after 
this  manner  will  stand  a  great  deal  of  rough  usage  without 
getting  broken  or  out  of  order. 

Nearly  all  closets  of  the  wash-down  type  are  now  made  in 
pedestal  form,  that  is  to  say,  with  a  hinged,  lifting  seat,  and  with- 
out wooden  casing  or  riser.  The  closet  is  then  well  adapted  for 
use  as  a  urinal  and  for  the  discharge  of  chamber  slops.  The 
space  under  the  closet  should  be  cemented  or  tiled,  or  lined  with 
lead  finished  with  a  beaded  border.  In  the  bracket  form  of 
closets,  the  basin  and  trap  are  supported  by  galvanized  cantilever 
brackets  let  into  the  wall,  and  do  not  rest  on  the  floor,  conse- 
quently all  the  space  beneath  the  closet  apparatus  can  be  readily 
cleansed.     Bracket  closets  are  much  used  in  hospitals. 

The  wash-out  closet  (fig.  17)  is  constructed  of  stoneware  or  china, 
with  the  basin  so  shaped  that  a  small  quantity  of  water  remains 
in  it  to  receive  the  excreta,  which  are  flushed  out  over  the  edge 
of  the  basin  into  a  siphon  trap  below.  This  form  of  closet  is 
difficult  to  flush  with  only  2  gallons  of  water,  for  the  rush  of  the 
water  from  the  flushing  cistern  is  broken  by  the  force  necessary 
to  clear  out  the  contents  of  the  basin;  and  then  the  water  falls 
into  the  trap,  but  often  without  sufficient  impetus  to  propel  the 
excreta  through  it.  The  basin,  too,  is  very  apt  to  become  soiled 
by  solid  matters  near  the  outlet.     The  basin — as  in  the  case  of 


DISPOSAL   OF    REFUSE 


Qi 


every  closet  basin — should  be  provided  with  a  flushing  rim. 
These  disadvantages  have  led  to  the  disuse  of  wash-out  closets. 

Various  "  siphonic  "  closets  are  now  made  by  P2nglish  manu- 
facturers, in  which  the  contents  of  the  basin  are  not  only  forced 
out  by  the  water-flush,  but  are  also  sucked  out  by  means  of  a 
temporarily  induced  siphonage  in  the  trap.  Not  all  of  these 
closets  are  rehable,  as  in  some  cases  it  has  been  found  that  foul 
water  returns  to  the  basin  after  flushing;  also  in  some  forms  of 
this  closet,  to  prevent  the  siphon  becoming  "  air  bound,"  air- 


SVPHONIC   jcr 
--SUPPLV   Ta  9ASt» 


Fig.  i8. — Century  Siphonic  Closet. 


escape  pipes  have  to  be  inserted — an  undesirable  complication 
of  what  should  be  a  simple  apparatus. 

Water-ivaste  preventing  cisterns  should  be  used  with  each  of 
these  three  forms  of  closet,  both  for  economy  of  water  and  to 
break  the  connection  between  the  house  cistern,  used  for  drink- 
ing water,  and  the  water-closet  basin.  Where  there  is  no  house 
cistern,  the  water  being  suppHed  by  constant  service,  the  water- 
waste  preventer  is  especially  necessary.  Numerous  outbreaks  of 
enteric  fever  have  been  attributed  to  the  ascent  of  foul  air  and 
liquid  filth  from  water-closet  basins  up  the  supply  pipes  into  the 
water  mains,  with  which  they  were  directly  connected.  One 
of  the  simplest  forms  of  water-waste  preventer  merely  has  a 


92  HYGIENE    AND    PUBLIC   HEALTH 

spindle  valve  in  the  cistern  on  the  supply  pipe  of  the  closet,  which 
can  be  raised  by  pulling  a  chain  attached  to  a  lever,  when  the 
water — 2  or  2|  gallons — is  discharged.  When  the  lever  is  de- 
pressed by  the  chain,  the  ball  valve  is  raised,  and  no  more  water 
can  enter  the  waste  preventer  as  long  as  the  chain  is  held.  The 
chain  must  be  held  until  the  waste  preventer  is  empty. 

The  best  form  of  water-waste  preventer  is  that  with  a  siphon 
action.  A  very  short  pull  of  the  chain  will  put  the  siphon  in 
action,  when  the  whole  contents  of  the  cistern  are  discharged 
through  the  flush  pipe  of  i|  to  ij  inches  in  diameter.  No  more 
water  can  then  escape  until  the  cistern  is  refilled  and  the  chain 
again  pulled.  There  are  numerous  forms  of  siphon  water-waste 
preventer.  The  especial  advantage  of  the  siphon  action  is  that 
the  cistern  is  emptied  by  a  very  short  pull  of  the  chain — an 
important  factor  in  the  proper  flushing  of  closets  used  by  careless 
persons. 

These  cisterns  should  be  fixed  at  a  height  of  not  less  than 
4  feet  above  the  closet  basin.  If  this  "  head  "  is  not  obtainable, 
a  good  flush  can  be  secured,  as  in  the  "  combination  "  closets,  by 
using  a  cistern,  fixed  at  the  seat  level,  with  a  comparatively 
large  outlet  pipe,  which  is  only  narrowed  just  before  it  joins  the 
basin. 

The  joint  between  the  china  or  stoneware  trap  and  lead  soil 
pipe  is  difficult  to  make  perfectly  secure  with  red  lead  as  a  joint- 
ing material.  Therefore  it  is  better  for  these  closets,  where  they 
must  be  connected  to  a  lead  soil  pipe,  to  have  lead  traps,  as  a 
wiped  joint  can  be  easily  made  between  the  closet  trap  and  the 
soil  pipe.  The  disadvantage  of  the  lead  trap  is  that  it  cannot  be 
enamelled  internally,  and  enamel  paints  soon  wear  off,  giving  a 
dirty  appearance  to  the  bottom  of  the  closet.  In  most  cases  a 
good  joint  is  made  by  wiping  a  brass  collar  on  to  the  lead  soil 
pipe,  when  the  joint  between  the  chain  trap  and  brass  collar  is 
made  with  Portland  cement,  a  little  asbestos  packing  being 
employed  to  prevent  the  cement  finding  its  way  into  the  interior 
of  the  pipe. 

Under  the  head  of  closets  with  a  movable  apparatus  for  retain- 
mg  water  in  the  basin,  wc  have  the  pan,  the  valve,  and  the  plug 
closets,  but  only  the  valve  closet  need  be  described,  as  pan  and 
plug  closets  are  no  longer  manufactured,  and  are  only  very 
occasionally  now  to  be  found. 

The  valve  closet  (fig  19),  which  is  now  largely  in  use,  consists 


DISPOSAL  OF   REFUSE 


93 


of  a  hemispherical  basin  of  china  or  stoneware,  with  a  circular 
outlet  at  its  lowest  part,  3  inches  in  diameter.  This  outlet  is 
closed  by  a  circular  water-tight  clack  valve,  hinged^at  one  side, 
where  it  is  connected  with  the  handle  of  the  closet.  On  raising 
the  handle,  the  free  edge  of  the  valve  is  depressed  into  a  metal 
valve  box,  just  large  enough  to  allow  the  valve  to  assume  a 
perpendicular  position.  The  valve  box  is  connected  at  its  lower 
part  with  a  trap — preferably  a  siphon  trap,  or  an  anti-D  trap 
formed  of  4-inch  lead  pipe — and  the  outlet  of  this  trap  is  con- 
nected with  the  soil  pipe.  The  valve  closet  should  be  flushed 
from  a  small  cistern  holding  6  or  8  gallons  of  water,  and  not 
from  a  water-waste  preventer,  as  it  is  necessar^'^  to  provide  a 


KtTIQtt     fi,p   — 


Fig.  19. — Era  Valve  Closet. 


considerable  "  after-flush  " — that  is  to  say,  to  allow  a  supply  of 
water  to  enter  the  basin  after  the  handle  is  released  and  the 
valve  closed. 

To  secure  an  after-flush,  some  form  of  "  regulator  "  valve  in 
the  supply  pipe  from  the  cistern  to  the  closet  basin  must  be 
used.  The  "  bellows  regulator,"  which  is  commonly  used,  con- 
sists of  a  piston  working  in  a  cylinder,  and  connected  with  the 
handle  of  the  closet  and  with  the  valve  in  the  supply  pipe.  The 
cylinder  is  provided  with  an  escape  pipe  for  air,  on  which  is  a 
tap  to  regulate  the  speed  with  which  the  air  escapes  and  the 
piston  falls.  When  the  handle  is  raised,  the  valve  in  the  supply 
pipe  is  opened,  and  the  piston  also  is  raised  ;  but  on  letting  go 


94  HYGIENE    AND   PUBLIC   HEALTH 

the  handle — the  clack  valve  to  the  closet  basin  being  then  closed 
— the  valve  on  the  supply  pipe  is  kept  open,  admitting  water 
to  the  basin,  until  the  piston  has  completely  fallen  and  thereby 
closed  it.  The  amount  of  after- flush,  which  is  directly  pro- 
portional to  the  slowness  with  which  the  piston  sinks  in  the 
cylinder,  can  be  regulated  to  a  nicety  by  the  tap  on  the  air- 
escape  pipe. 

As  the  outlet  to  the  closet  basin  is  guarded  by  a  water-tight 
valve,  the  basin  may  overflow  from  too  much  after-flush,  or  from 
the  throwing  in  of  slops.  It  is  necessary,  therefore,  to  provide 
an  overflow  pipe  to  the  basin;  this  is  usually  carried  from  near 
the  top  of  the  basin  into  the  valve  box  below,  after  forming  an 
\J^  bend,  which,  by  holding  water,  prevents  the  ascent  of  foul 
air  from  the  valve  box.  But  it  is  found  in  practice  that  foul 
matters  may  find  their  way  into  or  accumulate  in  the  overflow 
pipe,  and  that  the  water  in  the  bend  is  liable  to  be  evaporated 
or  drawn  out  by  siphonage  when  the  contents  of  the  basin  are 
discharged  through  the  valve  box. 

Two  precautions  are  adopted  to  obviate  this  difficulty.  The 
first  is  to  carry  the  overflow  pipe  into  that  side  of  the  valve  box 
where  its  open  end  will  be  protected  by  the  depressed  valve  ; 
and  the  second,  which  is  most  necessary,  is  to  recharge  the  water 
in  the  overflow  at  each  use  of  the  closet.  The  basin  of  the  closet 
should  be  provided  with  a  flushing  rim.  Occasionally  a  ven- 
tilating or  "  puff  "  pipe  is  attached  to  the  valve  box,  and  carried 
up  and  out  into  the  open  air,  being  left  with  an  open  end  away 
from  any  windows.  When  the  contents  of  the  basin  are  being 
discharged,  the  foul  air  in  the  valve  box  then  escapes  into  the 
open  air,  instead  of  into  the  closet  compartment. 

There  is  very  little  risk  of  the  deposition  of  filth  in  any  part 
of  the  apparatus,  as  the  large  volume  of  water  which  the  basin 
can  contain  effectually  flushes  the  small  valve  box  and  trap 
beneath.  Occasionally  the  valve  box  is  enamelled  inside  to 
prevent  corrosion.  The  chief  disadvantage  of  the  closet  is  that 
the  clack  valve  may  become  in  time  leaky,  allowing  the  water 
in  the  basin  to  escape,  and  possibly  foul  air  to  ascend  into  the 
general  air  of  the  closet. 

Wherever  a  valve  closet  is  used  as  a  urinal  or  for  the  reception 
of  chamber  slops,  a  white  ware  slop-top  should  be  fitted,  and 
the  seat  should  be  hinged  for  lifting.  Valve  closets  are  also  now 
made  in  pedestal  form,  so  as  to  obviate  the  wooden  casing  and 


DISPOSAL    OF    REFUSE  95 

riser.  An  advantage  possessed  by  valve  closets  over  the  wash- 
down  closets  is  that  the  flushing  is  comparatively  noiseless  ;  and 
this  fact  accounts  for  their  popularity  in  the  best  class  of  resi- 
dential property. 

In  the  anti-D  trap  the  calibre  of  the  pipe  is  diminished  in  the 
bent  portion  which  holds  the  trapping  water,  and  the  bend  of 
the  pipe  beyond  the  trap  instead  of  being  circular  is  squared. 
These  properties  cause  some  resistance  to  the  passage  of  water 
through  the  trap,  and  tend  to  prevent  both  siphonage  by  suction 
— i.e.,  the  drawing  of  the  water  in  the  trap  by  the  passage  of 
water  down  the  soil  pipe  from  a  higher  level — and  siphonage  by 
momentum,  which  may  occur  in  plain  siphon  traps  by  the  water 
discharged  from  the  water-closet  sweeping  through  the  trap, 
insufftcient  remaining  behind  to  form  the  water-seal.  The  depth 
of  the  water-seal  in  water-closet  traps  should  not  be  less  than 
I  inch,  and  not  greater  than  if  inches.  If  the  depth  of  the  water- 
seal  is  too  small,  there  is  a  hability  for  the  trap  to  be  unsealed  ; 
if  the  seal  is  too  great,  the  trap  and  the  closet  above  it  are  not 
self-cleansing  with  an  ordinary  flush  of  water.  These  remarks 
apply  more  especially  to  "  wash-down  "  closets  (short  hoppers) 
with  water-waste  preventers. 

The  Water-sea!  of  Traps. — The  water-seal  ot  a  trap  is  the  vertical  distance 
between  the  level  at  which  water  stands  when  the  trap  is  fixed  in  position, 
and  the  lowest  point  of  the  bend  of  the  upper  surface  of  the  trap.  Thus  in 
figs.  20  and  21,  which  are  diagrammatic  sections  of  a  S-trap  and  a  P-trap,  in 
each  case  the  water-seal  is  the  same,  namely,  the  vertical  distance  AB  in  the 
case  of  the  S-trap.  and  the  vertical  distance  A'  B'  in  the  case  of  the  P-lrap 


Fig.  20. — S-TRAP,  WITH  Water-seal.   Fig.  21 . — P-trap,  with  Water-seal. 

The  water-seal  is,  in  fact,  the  depth  of  water  that  opposes  the  passage  of  air 
or  gases  from  one  side  of  the  trap  to  the  other,  from  outlet  to  inlet  or  from 
inlet  to  outlet.  In  the  figures,  the  upper  dotted  line  represents  the  water- 
level  in  each  trap,  and  the  lower  dotted  line  is  parallel  with  the  upper 
dotted  line,  and  is  tangential  to  the  apices  of  the  bends. 

On  the  floor  beneath  the  closet  basin  is  usually  placed  a  lead 
safe-tray,  to  catch  any  overflow.  This  tray  should  be  provided 
with  a  waste  pipe,  which  must  be  carried  through  the  wall  into 
the  outer  air,  its  end  being  covered  by  a  brass  flapper  to  prevent 


g6  HYGIENE    AND    PUBLIC   HEALTH 

cold  currents  of  air  passing  into  the  house.  It  was  formerly  the 
custom  to  connect  this  waste  pipe  with  the  D  trap  under  the 
closet  basin,  thereby  permitting  foul  air  to  enter  the  house  at 
all  times. 

\^'ater-closets  should  be  placed  against  the  outside  wall  of  a 
building,  in  which  is  a  window  with  an  area  of  at  least  2  square 
feet,  made  to  open,  and  reaching  to  the  ceiling.  Where  possible 
they  should  be  separated  from  the  house  by  a  well-ventilated 
lobby,  for  it  is  important  that  air  from  the  closet  should  find  an 
easy  exit  to  the  outer  air,  and  not  pass  into  the  house,  as  so 
often  happens  when  water-closets  are  placed  in  dark,  unventi- 
lated  corners.  The  water-closet  must  not  open  directly  into  any 
living-room,  factory,  workshop  or  compartment  in  which  food 
is  stored.     The  division  wall  between  the  water-closet  and  a 


Fig.  22. — Trough  W.\ter-closet. 


dwelling- room,  or  a  factory,  or  workshop,  or  food  store,  should 
always  be  of  brick,  and  not  a  porous  lath  and  plaster  structure. 
The  trough  closet  is  used  in  large  establishments,  as  hospitals, 
schools,  workhouses,  and  asylums.  One  apparatus  serves  for 
the  use  of  several  people  at  the  same  time,  and  the  flushing  can 
be  rendered  automatic.  The  old  form  of  closet  (fig.  22)  con- 
sists of  an  open  trough,  usually  of  stoneware,  with  rounded 
bottom,  of  varjring  length  according  to  the  number  of  compart- 
ments desired.  The  trough  has  a  slight  incline  towards  the 
drain ;  and  by  means  of  a  weir  at  its  lower  end  it  is  able  to  retain 
sufftcient  water  to  cover  the  bottom  for  its  whole  length.  It 
terminates  in  a  siphon  trap  protected  by  a  grid,  to  keep  back 
articles  improperly  thrown  in,  before  joining  the  drain.  Each 
seat  over  the  trough  sliould  be  in  a  separate  compartment.  The 
closet  may  be  flushed  by  means  ot  a  Field's  annular  siphon  flush 


DISPOSAL   OF   REFUSE 


97 


tank  {see  fig.  14)  of  capacity  proportional  to  the  length  of  the 
trough  to  be  flushed. 

The  more  modern  and  approved  type  of  trough  w.c.  or  latrine 
is  a  great  improvement  upon  the  old  form.  In  this  (fig.  23)  the 
trough  is  retained,  but  each  closet  is  cut  off  from  its  neighbours 
by  a  separate  basin,  the  outlet  from  which  dips  into  the  water  in 


I        '  '« 


->  ■'Si~:'--J^>c'  ?>*>;-'.>-'-.V  '-<i 


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'f' 

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riH^l;;,, 

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Fig.  23. 


New  Form  of  Trough   Closet  or  Latrine  with 
Isolated  Pans. 


the  trough.  The  trough,  moreover,  is  kept  filled  with  water, 
which  also  rises  up  for  a  few  inches  into  each  w.c.  basin;  this  is 
effected  by  doing  away  with  the  weir  and  substituting  a  high 
siphon  trap  at  the  outlet  to  the  trough.  Each  separate  basin 
is  flushed  through  its  flushing  rim  every  time  the  automatic 
flush  tank  discharges,  this  discharge  causing  the  emptying  of  the 
basins  and  trough  by  siphonic  action.     On  the  whole,  trough 

7 


98  HYGIENE    AND    PUBLIC   HEALTH 

closets  have  not  been  found  to  be  very  satisfactory  in  practice, 
and  in  schools  and  institutions  they  are  now  being  replaced  by 
separate  pedestal  wash-down  closets. 

Waste-water  closets,  in  which  the  excreta  are  carried  away  by 
means  of  the  house  waste-waters,  and  in  which  flushing  cisterns 
with  separate  water  supply  are  not  used,  were  originally  intro- 
duced by  Dr.  Alfred  Hill,  and  are  now  to  be  seen  in  many  working- 
class  houses  in  Midland  towns. 

The  annexed  figure  (fig.  24)  shows  a  section  through  Day's 
waste-water  closet.  In  this  pattern  the  excreta  fall  into  a 
stoneware  tipper,  which  also  receives  the  waste  water.     This 


Fig.  24. — Day'.s  Waste-water  Closet. 


tipper  is  so  balanced  on  its  bearings  that  when  full  it  automati- 
cally tips  over  and  discharges  its  contents  (f<eces,  urine,  paper, 
and  waste  water)  into  the  siphon  trap  below,  which  leads  to  the 
drain.  The  entrance  to  the  siphon  trap  is  considerably  narrowed 
transversely,  so  as  to  pre^■ent  bulkj^  articles  improperly  intro- 
duced finding  their  way  into  and  obstructing  the  drain.  The 
upper  part  of  the  closet  is  so  constructed  as  to  prevent,  as  far 
as  possible,  fouling  of  the  sides  above  the  tipping  basin;  and 
this  upper  part  can  be  taken  down  easily  and  removed  for 
cleaning. 

In   another  pattern   of  waste-water  closet   the  tipper  is  not 


DISPOSAL   OF    REFUSE  99 

placed  under  the  seat,  but  in  some  position  between  the  closet 
and  the  gulley  into  which  the  house  waste  water  empties  itself. 
The  discharge  of  water  from  the  tipper  flushes  the  drain  in  which 
the  excreta  are  deposited  direct  from  the  closet. 

The  advantages  of  this  system  of  waste-water  closets  are  that 
clean  water  is  not  required  for  flushing,  a  head  of  water  is  not 
necessary,  there  is  no  delicate  apparatus  to  be  damaged  and  get 
out  of  order  b}^  rough  usage,  and  both  the  primary  cost  and 
the  outlay  in  keeping  in  repair  are  small.  On  the  other  hand, 
the  economy  of  clean  water  and  the  absence  of  dilution  cause  the 
sewage  passing  from  districts  supplied  with  these  forms  of  closets 
to  be  very  strong  and  foul ;  and  the  difficulty  of  satisfactory  treat- 
ment of  the  sewage  at  the  outfall  is  much  enhanced.  Economy 
of  water  is  purchased  at  the  expense  of  difficulties  in  the  purifica- 
tion of  the  sewage.  Moreover,  waste-water  closets  are  liable  to 
get  foul  and  to  block  up,  for  in  the  poorer  class  houses  with  no 
bathrooms  the  slop-waters  may  not  be  adequate  to  provide  suffi- 
cient flushing.  It  should  be  stated  that  waste-water  closets 
should  only  be  fitted  up  outside  dwelling  houses.  In  the  Mid- 
lands these  closets  are  not  now  regarded  with  favour,  and  the 
system  is  not  being  extended. 

Urinals  should  be  made  of  non-corrosive  materials,  such  as 
fireclay,  slate,  and  stoneware;  all  metal  apparatus  is  liable  to 
corrosion,  and  should  not  be  used.  The  floor  should  be  cemented, 
and  should  slope  towards  a  channel  which  discharges  into  a 
siphon  trap  connected  with  a  drain.  Urinal  basins  may  be 
made  of  china  or  stoneware,  constructed  so  as  to  retain  water, 
and  their  waste  pipes  should  discharge  over  the  channel  in  the 
floor.  The  best  kind  of  flush  is  that  from  siphon-action  flush 
tanks  which  discharge  automatically  at  regular  intervals.  Unless 
urinals  are  regularly  and  freely  flushed  with  water,  there  will  be 
a  deposit  of  urates  in  the  attached  lead  waste  pipe,  soil  pipe,  or 
drain,  which  by  continual  accretion  and  hardening  eventually 
leads  to  obstruction.  Where  urinals  are  not  supplied  with 
water,  there  is  usually  a  nuisance  from  smell,  but  this  can  be 
largely  obviated  by  brushing  the  backs  and  sides  daily  with 
paraffin. 

Slop  sinks  should  be  used  only  where  it  is  objectionable  to 
discharge  slops  from  bedrooms  through  the  water-closets.  They 
are  usually  short  hopper  china  basins  with  a  siphon  trap  below, 
protected  by  a  grid  to  keep  back  the  larger  foreign  bodies  which 


100  HYGIENE    AND    PUBLIC   HEALTH 

might  obstruct  the  pipes.  The  trap  should  be  connected  with 
the  soil  pipe  like  a  water-closet.  They  should  be  provided  with 
a  flushing  rim,  and  flushed  from  a  water-waste  preventer. 

Soil  pipes  are  used  to  receive  the  contents  of  water-closets, 
urinals,  and  slop  sinks,  which  are  above  the  basement  or  ground 
level.  They  should  be  circular  in  section,  and  3|  or  4  inches  in 
diameter,  these  being  the  most  convenient  sizes  for  ordinary  use. 
They  should  be  of  drawn,  milled,  or  rolled  lead,  8  pounds  to  the 
square  foot,  or  9  pounds  to  the  square  foot  for  very  high  buildings, 
without  any  longitudinal  seam,  and  should  be  fixed  outside  the 
house,  with  wiped  (soldered)  joints  between  the  different  lengths 
of  pipe,  each  pipe  being  10  feet  in  length.  Lead  T-pieces  are 
used  to  receive  the  branches  from  the  water-closets. 

The  London  County  Council  Byelaws  require  3i-inch  lead  soil  pipes  to 
weigh  not  less  than  65  lb.  per  10  feet  length,  and  4-inch  pipes  not  less  than 
74  lb.  per  10  feet  length.  The  thickness  of  metal  of  3^  -inch  and  4-inch  iron 
soil  pipes  must  be  not  less  than  y'ij  inch;  and  the  weight  of  4-inch  iron  pipes 
per  6  feet  length  (including  socket  and  headed  spigot  or  flanges,  the  socket 
not  to  be  less  than  |  inch  thick)  must  be  not  less  than  54  lb. 

Soil  pipes  outside  the  house  are  often  made  of  light  cast  iron 
or  galvanized  iron.  They  are  inferior  to  lead  pipes,  as  the 
internal  surface  of  iron  pipes  is  much  rougher  than  that  of  lead, 
and  the  joints  as  usually  made  with  red  lead  putty  are  insecure. 
Heavy  cast-iron  socketed  soil  pipes  are  in  some  cases  insisted 
on  by  local  drainage  byelaws,  especial  precautions  being  laid 
down  for  the  construction  of  the  joints  between  the  different 
lengths.  To  prevent  oxidation  and  the  formation  of  rust,  iron 
soil  pipes  should  be  coated  inside  and  outside  with  the  magnetic 
oxide  of  iron  (Barff's  process),  with  hot  coal-tar  pitch,  or  with 
Angus  Smith's  solution.  All  cast-iron  pipes  must  be  free  from 
holes  or  other  defects,  and  properly  tested,  and  of  a  uniform 
thickness  of  not  less  than  y,,  inch.  The  joints  between  the 
different  lengths  must  be  caulked^  with  lead;  and  the  joints 
between  the  iron  pipe  and  the  lead  T-pieces  from  the  closets 
should  be  made  with  a  brass  ferrule,  caulked  in  with  lead,  the 
lead  pipe  being  attached  to  the  ferrule  by  a  wiped  joint.    Heavy 

^  A  caulked  lead  joint  is  a  joint  made  by  firmly  packing  lead  strips 
into  the  socket  of  the  iron  pipe  by  means  of  a  caulking  tool  (which  is  in 
the  form  of  a  Ijlunt  chisel)  and  a  hammer.  The  lead  is  known  in  the  trade 
as  '  ribbon  "  lead.  It  should  be  quite  free  from  oxide,  and  therefore  must 
only  be  used  when  fresh.  This  process  has  now  largely  superseded  the 
older  method  of  caulking  with  oakum  and  filling  in  with  molten  lead. 


DISPOSAL   OF    REFUSE  I 01 

iron  soil  pipes  are  heavier  than  lead  pipes  in  the  proportion  of 
about  9  to  7-4. 

Joints  of  Pipes. — In  making  a  wiped  soldered  joint  on  lead 
pipes,  the  upper  end  of  the  lower  pipe  is  opened  out  about  ^-  inch. 
The  lower  end  of  the  upper  or  male  pipe  is  next  rasped  so  as  to 
make  it  fit  into  the  opened-out  end  of  the  female  pipe.  The 
ends  of  the  pipes  which  are  to  be  covered  with  solder  are  next 
shaved  with  a  shave  hook,  so  as  to  take  the  dulness  off  the  lead 
and  allow  the  solder  to  readily  tin  upon  them. 

Above  and  below  the  soldered  line  (fig.  25)  the  pipes  are  then 
soiled  round  with  plumber's  soil  (a  mixture  of  lampblack  and 
size)  to  prevent  the  solder  adhering.  It  is  well  also  to  soil  the 
insides  of  the  pipes  to  prevent  the  solder  adhering  here  and 
causing  projections.  The  male  end  is  next  fixed  into  the  female 
end,  and  a  collar  placed  round  the  bottom  of  the  joint  to  catch 


Fig.   25. 


Fig.  26. 

the  solder  as  it  falls  off.  The  heated  solder  (a  mixture  of  two 
parts  of  soft  lead  to  one  of  tin)  is  then  poured  over  the  shaped 
ends  of  the  pipes,  and  gradually  worked  into  the  right  shape.  A 
hot  moleskin  cloth  is  now  taken  and  wiped  round  the  joint,  so 
as  to  leave  it  of  the  shape  shown  in  fig.  25.  As  the  pipes  become 
heated  by  the  solder  splashed  over  them,  the  solder  penetrates 
between  the  ends  of  the  pipes  and  readily  adheres  to  all  the  shaved 
bright  surfaces  exposed,  leaving  when  cool  a  homogeneous  mass 
of  metal.  Fig.  26  shows  a  joint  made  with  a  copper  bit  or  blow- 
pipe. The  ends  of  the  pipe  are  heated  either  with  a  copper  bit 
or  blowpipe,  and,  when  hot,  the  solder  is  poured  around  the 
point  of  junction  and  penetrates  between  the  cut  ends.  A  very 
good  joint  is  thus  obtained  with  little  trouble,  but  inferior  in 
strength  to  the  wiped  joint  with  its  strengthening  band  of  solder. 
A  new  method  of  jointing  pipes  has  lately  been  introduced, 
which    is    intended    to    supersede    the    old-fashioned    soldering 


102  HYGIENE    AND    PUBLIC   HEALTH 

methods.  For  jointing  lead  pipes  a  cutting  tool  is  used,  the  ends 
of  the  pipe  being  shaped  into  a  coned  joint,  and  the  surfaces  left 
in  perfect  apposition.  A  substance  called  "  Amalgaline  "  is  then 
inserted  between  the  cut  ends,  and  the  exterior  of  the  joint  is 
heated  with  a  flame.  Amalgaline  consists  of  a  metallic  ribbon, 
0-05  millimetre  thick,  coated  with  a  composition  to  prevent 
oxidation.  On  the  application  of  heat,  the  ribbon  melts  at 
a  lower  temperature  than  the  metals  to  be  acted  upon,  and 
causes  an  amalgamation  of  the  metals  at  a  considerably  lower 
temperature  than  their  normal  melting-point. 

The  joints  between  iron  pipes  can  only  be  caulked  with  lead 
when  the  pipes  are  of  sufficient  substance  and  strength  to  stand 
it.  The  joints  of  the  light  iron  pipes  commonly  used  are  made 
with  spun  yarn  and  red  lead,  or  occasionally  with  Portland 
cement. 

If  lead  soil  pipes  are  used  where  much  hot  water  is  discharged 
through  water-closets  or  slop  sinks  connected  with  them,  owing 
to  the  expansion  of  the  metal  of  the  rigid  pipe,  twisting  and  con- 
tortion takes  place  (the  pipes  are  said  to  "  buckle  "),  and  such 
pipes  readily  wear  out.  Under  such  circumstances,  either  iron 
soil  pipes  should  be  used,  or  the  lead  pipes,  if  outside  the  house 
and  not  near  windows,  should  have  slip  joints  or  rubber  expan- 
sion joints.^  For  this  reason,  also,  south  and  west  aspects, 
involving  much  exposure  to  the  sun,  should  be  avoided  for  lead 
soil  pipes. 

With  the  precautions  noted  above,  and  under  skilled  work- 
manship, cast-iron  soil  pipes  may  be  used  outside  a  house. 
Stoneware,  zinc,  or  wrought  iron  should  never  be  used  for  soil 
pipes;  for  stoneware  is  too  heavy,  and  zinc  is  thin  and  liable, 
like  iron,  to  erosions.  The  proper  fixing  of  a  lead  soil  pipe  by 
means  of  cast  lead  ears  or  tacks  to  the  walls  of  the  house  at 
intervals  of  3-4  feet,  to  insure  its  being  perfectly  rigid,  is  a  point 
of  importance;  if  not  securely  fixed,  there  will  be  strain  on  some 
or  all  of  the  joints,  with  the  result  of  their  becoming  insecure. 
Outside  soil  pipes  should  be  connected  with  the  house  drain  by 
a  plain  stoneware  bend  below  the  ground  level,  a  thimble  or 
ferrule  of  rough  brass  casting  being  wiped  on  to  the  lead  pipe  and 
a  Portland  cement  joint  being  made  between  the  brass  and  stone- 

'  A  slip  joint  is  made  by  .«lip]nng  the  end  of  one  pipe  into  the  slightly 
('X]);in(le(l  end  of  another  pipe,  so  that  the  one  lits  more  or  less  lirmly  into 
the  other,  but  allowing  a  certain  amount  of  play  for  expansion. 


DISPOSAL   OF    REFUSE 


103 


? 


ware.  An  iron  soil  pipe  should  be  connected  with  the  stoneware 
drain  by  receiving  the  spigot  end  of  the  iron  soil  pipe  into  the 
socket  end  of  the  stoneware  drain,  and  making  the  joint  with 
Portland  cement.  When  a  branch  lead  soil 
pipe  has  to  be  connected  to  a  heavy  iron  main 
soil  pipe  a  brass  ferrule  or  thimble  is  soldered 
to  the  lower  end  of  the  lead  pipe,  and  the 
ferrule  is  then  jointed  with  the  socket  of  the 
iron  pipe  by  means  of  hemp  and  molten  lead, 
or  the  "  ribbon  "  lead  previously  alluded  to. 
All  soil  pipes,  whether  inside  or  outside  the 
house,  should  be  carried  up  full  bore  above 
the  entrance  of  the  branch  from  the  highest 
water-closet  to  the  top  of  the  house  (fig.  27) 
above  the  ridge  of  the  roof,  clear  of  all  windows 
and  chimneys,  their  ends  being  left  open  or 
covered  merely  with  a  wire-gauze  dome  to 
prevent  birds  from  building  in  them.  Cowls 
should  not  be  placed  on  the  tops  of  soil  pipe 
ventilators.  They  are  useless  as  aids  to  extrac- 
tion of  air;  and  they  very  frequently  lead  to  ob- 
struction of  the  outlet,  besides  being  perishable. 
Where  one  soil  pipe  receives  the  'discharges 
of  several  water-closets  on  different  floors,  the 
passage  of  the  contents  of  one  of  the  upper 
closets  down  the  soil  pipe  may  cause  the  water 
in  the  trap  of  one  of  the  lower  closets  to  be 
drawn  off,  owing  to  the  suctional  force  of  the 
downward  current  of  air  caused  by  the  descent 
of  the  liquid  in  the  soil  pipe.  To  prevent  this 
siphonage  by  suction  taking  place,  a  2-inch  or 
2|-inch  lead  ventilating  pipe  should  be  carried 
up  from  every  branch  soil  pipe,  a  few  inches 
beyond  the  trap  (on  its  soil  pipe  side),  and 
these  anti-siphonage  pipes  should  join  with  one 
another  on  their  way  up  outside  the  house,  the 
common  pipe  being  carried  up  separately  or  con- 
nected with  the  ventilator  to  the  soil  pipe  (fig.  27).  By  this 
means  the  water-closet  traps  will  not  be  disturbed  by  the  passage 
of  liquid  down  the  soil  pipe,  for  air  will  be  sucked  down  these  anti- 
siphonage  pipes  to  restore  the  disturbed  equilibrium.     Siphonage 


3; 


Fig.  27.^Soil 
Pipe  and  Venti- 
lator, WITH  Anti- 
siphonage  Pipes 
FROM  THE  Water- 
closet  Branches. 


i04  HYGtENE   AND   PUJBLIC  HEALTH 

is  most  likely  to  occur  in  3|-inch  lead  soil  pipes  where  the  branch 
pipes  from  the  water-closet  traps  to  the  soil  pipe  are  long  and 
curved.  If  they  are  short  and  straight,  there  is  less  hkelihood 
of  siphonage  occurring.  The  long  arms  or  branches  from  water- 
closets  thus  ventilated  are  relieved  of  foul  air  which  otherwise 
accumulates  in  them,  and  eventually  leads  to  erosion  and  per- 
foration of  the  metal  of  which  the  pipes  are  made.  A  trap 
at  the  foot  of  the  soil  pipe  immensely  intensifies  siphonage  by 
suction. 

Rain-water  pipes  from  the  roof  should  not  be  used  as  soil 
pipes  and  ventilators,  for  during  heavy  rain,  when  it  may  be 
most  necessary  to  give  a  safe  exit  for  displaced  drain  air,  they 
will  be  useless  as  ventilators,  and  foul  air  from  unventilated 
drains  may  be  forced  through  water-closet  traps  into  the  houses. 
Moreover,  the  joints  of  rain-water  pipes  are  frequently  found  to 
be  defective;  and  if  the  pipe  passed  near  to  windows  there  would 
be  a  risk  of  dram  gases  finding  an  entrance  into  the  house. 

House  clyains  are  usually  constructed  of  circular  glazed  stone- 
ware socketed  pipes,  2  feet  in  length,  with  cemented  joints  (Port- 
land cement) .  The  pipes  are  also  connected  by  Stanford's  patent 
joints  or  Doulton's  modification  (which  makes  the  pipes  adjust- 
able in  any  position),  in  which  the  spigot  and  socket  ends  of  each 
pipe  are  provided  with  a  mould  of  smooth  plastic  material, 
causing  them  to  fit  accurately  into  each  other  when  in  position ; 
a  very  perfect  joint  being  formed  by  greasing  the  prepared  ends 
with  a  little  rosin  and  melted  tallow.  These  patent  joints,  how- 
ever, are  inferior  to  cement,  as  they  are  liable  to  erosion  and 
decay,  and  are  usually  found  not  to  be  watertight  some  years 
after  laying. 

Stoneware  pipes  are  less  porous  and  more  durable  than  earthen- 
ware pipes;  the  former  may  be  distinguished  from  the  latter  by 
their  colour  (generally  pale  buff),  the  ringing  note  which  they 
give  out  on  being  struck  with  a  hammer,  and  their  comparatively 
slight  increase  in  weight  after  twenty-four  hours'  immersion  in 
water. 

Portland  cement  is  a  mixture  of  chalk  and  clay  burnt  at  a 
high  temperature  and  subsequently  ground  very  fine.  It  is 
stronger  and  capable  of  bearing  greater  tensile  strains  than  other 
cements  (Roman  and  Medina),  but  does  not  set  so  rapidly. 
When  cemented  joints  are  made,  neat  Portland  cement  only 
should  be  used,  and  care  must  be  taken  to  remove  any  cement 


DISPOSAL   OF    REFUSE  IO5 

projecting  from  the  interior  of  the  joint  into  the  drain,  whicli 
when  hardened  would  form  an  obstruction  to  the  flow  of  sewage 
through  the  drain.  Portland  cement  should  be  spread  out  and 
exposed  to  the  air  for  some  time  before  it  is  used,  otherwise  the 
joints,  when  made,  are  apt  to  "  blow,"  and  the  collars  become 
fractured.  Socketed  cast-iron  pipes  coated  inside  and  outside 
with  some  preservative  material  such  as  the  magnetic  oxide  of 
iron  (Barff  process)  or  Angus  Smith's  solution,  to  prevent  oxida- 
tion, are  used  when  the  drain  is  required  to  be  of  extra  strength 
to  withstand  constant  vibration,  as  when  laid  under  roads  or 
paths  on  which  there  is  heavy  traffic,  and  also  in  soft,  swampy 
ground.  The  joints  of  an  iron  drain  must  be  caulked  with  molten 
lead  and  gasket  or  hemp  (old  method),  or  with  "  ribbon " 
lead  (new  method) .  Iron  pipes  have  advantages  over  stoneware 
as  they  are  made  in  g-feet  and  12-feet  lengths,  and  consequently 
fewer  joints  are  required;  the  pipes  are  stronger,  and  the  caulked 
lead  joints  more  durable,  and  they  are  capable  of  resisting  strains 
that  would  fracture  stoneware  pipes;  on  the  other  hand,  the 
interiors  of  even  the  best  protected  iron  drains  are  liable  to  rusting 
and  erosion  in  course  of  time,  a  defect  which  the  less  costly 
stoneware  drains  are  free  from. 

When  it  is  necessary  to  connect  a  lead  to  a  heavy  iron  pipe, 
a  strong  brass  ferrule  or  thimble  should  be  joined  to  the  lead 
pipe  by  means  of  a  wiped  soldered  joint;  the  brass  ferrule  is 
then  received  into  the  socket  of  the  iron  pipe  and  the  joint  made 
with  hemp  and  molten  lead,  or  "  ribbon  "  lead. 

For  small  and  medium-sized  houses  a  drain  4  inches  in  diameter 
is  the  proper  size;  for  large  houses  a  6-inch  drain  may  be  used, 
and  for  large  institutions  or  establishments  consisting  of  several 
buildings  a  9-inch  drain  may  rarely  be  required.  The  smaller 
the  drain,  the  better  the  flushing  and  removal  of  deposit;  but 
the  drain  must  in  all  cases  be  large  enough  to  guard  against 
blockage  and  to  carry  off  at  all  times  all  the  rainfall  over  the 
area  drained,  as  well  as  the  maximum  flow  of  sewage  proper  of 
the  house.  A  volume  of  water  sufficient  to  rnake  a  4-inch  pipe 
run  full  causes  a  6-inch  pipe  to  run  less  than  half-full,  and  a 
9-inch  pipe  only  about  a  quarter  full,  when  all  three  are  laid  at 
the  same  inclination,  since  the  sectional  areas  of  the  three  pipes 
are  in  the  ratio  of  about  i,  2,  and  5. 

Stoneware  drains  are  made  in  3-inch,  4-inch,  6-inch,  9-inch, 
12-inch,   15-inch,  and  18-inch  sizes.     Iron  drains  are  made  in 


I06  HYGIENE    AND    PUBLIC   HEALTH 

these  sizes,  and  in  addition  5  inches  in  diameter — a  size  which 
is  very  frequently  employed. 

The  London  County  Council  Byelaws  require  stoneware  drains  (4-inch 
and  6-inch)  to  be  not  less  than  |-  inch  in  thickness;  the  depth  of  the  socket 
to  be  i|  inches  for  4-inch,  and  2  inches  for  6-inch  pipes;  and  the  annular 
space  for  the  cement  to  be  not  less  than  ^^'^  inch  for  both  4-inch  and  6-inch 
drains.  For  iron  drains  (4-inch,  5 -inch,  and  6-inch)  the  thickness  of  metal 
must  not  be  less  than  ^  inch;  and  the  weight  per  9  feet  length  (including 
socket  and  beaded  spigot  or  flanges,  the  socket  not  to  be  less  than  ^  inch 
thick)  must  be  not  less  than  160  lb.  for  4-inch  drains,  190  lb.  for  5-inch 
drains,  and  230  lb.  for  6-inch  drains. 

The  pipes  must  be  laid  (with  the  socket  end  pointing  upwards 
towards  the  head  or  commencement  of  the  drain)  on  a  perfectly 
smooth  incline  of  hard  ground,  or  where  passing  under  the 
basement  of  a  house,  on  a  bed  of  6  inches  of  cement  concrete, 
the  drain  being  embedded  to  the  extent  of  half  its  diameter. 
In  London  it  is  the  practice  in  addition  to  cover  stoneware 
drains  with  6  linches  of  cement  concrete  all  round,  the  concrete 
projecting  on  each  side  of  the  drain  to  an  extent  equal  to  the 
external  diameter  of  the  drain.  Concrete  should  be  made  of 
clean  sharp  sand,  2  parts;  clean  ballast  (gravel,  or  hard  brick 
broken  small),  6  parts;  Portland  cement,  i  part.  Each  pipe 
should  rest  upon  the  concrete  for  its  whole  length,  so  that  the 
drain  may  be  truly  laid,  the  lumen  of  each  pipe  being  concentric 
with  the  next.  The  concrete  should  be  hollowed  out  where  the 
collar  of  the  pipe  rests,  and  the  cement  must  be  introduced  all 
round  the  joint,  below  as  well  as  above;  and  the  joint  should 
be  finished  with  the  trowel.  It  is  sometimes  the  practice  to 
introduce  a  strand  of  spun  yarn  into  the  interior  of  the  joint  to 
prevent  the  cement  passing  into  the  drain,  and  to  insure  the 
thickness  of  cement  being  the  same  all  round.  It  is  often  the 
custom  now  to  lay  the  drain  on  bricks  at  the  bottom  of  the 
trench,  and  when  the  joints  have  been  made  with  cement,  to 
fill  in  with  concrete  beneath  the  pipes.  If  this  is  done,  a  brick 
should  be  used  to  support  each  end  of  every  pipe,  so  that  the 
drain  may  he  truly  laid.  Iron  drains  should  be  laid  on  6  inches 
of  concrete,  where  passing  under  a  l)uilding,  as  above  described 
for  stoneware  drains,  but  need  not  be  embedded  in  concrete. 

The  gradient  of  a  4-inch  drain  should,  if  possible,  be  not  less 
than  I  in  40,  of  a  6-incli  drain  i  in  60,  and  of  a  9-inch  drain  i 
in  go;  this  will  give  in  each  case  a  velocity  of  flow  of  between  3 
and  4  feet  per  second.     The  drain  should  not,  wherever  it  can  be 


DISPOSAL   OF   REFUSE  IO7 

avoided,  be  carried  under  tlie  basement  of  a  house.  Where, 
however,  this  is  unavoidable,  the  special  precautions  noticed 
above  must  be  taken,  and  at  the  point  where  the  drain  leaves 
the  premises  the  wall  should  be  supported  by  a  relieving  arch 
to  prevent  settlement  and  fracture  of  the  pipes. 

Drains  should  be  laid  as  far  as  possible  in  straight  lines.  If 
a  bend  is  necessary,  it  should  be  effected  by  means  of  a  special 
pipe  curved  to  the  proper  degree,  and  the  radius  of  any  curve 
should  not  be  less  than  ten  times  the  cross-sectional  diameter 
of  the  drain  or  sewer.  The  bends  most  commonly  used  are 
known  as  ],  I,  and  V.t  bends,  implying  that  if  4,  8,  or  16  respec- 
tively of  these  pipes  are  placed  together  they  will  form  a  complete 
circle.  A  branch  drain  should  be  made  to  join  the  main  drain  by 
means  of  a  V-junction  pipe,  so  that  the  branch  current  may  be 
flowing  nearly  in  the  direction  of  the  main  current,  thus  causing 
no  obstruction  at  the  point  of  union.  In  large  houses  it  is  very 
often  impossible  to  carry  the  drain  in  a  straight  line  for  its 
whole  length.  It  is  advisable  in  these  cases,  at  every  change  of 
direction,  to  provide  means  of  inspection  by  manhole  chambers, 
the  drain  being  continued  through  the  floor  of  the  chamber  by 
a  suitably  curved  channel  pipe,  i.e.,  a  pipe  divided  longitudinally 
in  half.  Into  these  inspection-chambers  the  branch  drains  also 
should  l)e  made  to  discharge  by  means  of  short  curved  channel 
pipes  emptying  over  the  main  channel.  Winser's  curved  channel 
pipes,  from  which  about  a  quarter  section  only  of  the  circum- 
ference has  been  removed,  should  be  used  when  connected  with 
a  high  soil  pipe,  so  as  to  avoid  splashing  of  solid  fsscal  matters 
over  the  floor  of  the  chamber;  and  where  the  drains  are  joined 
in  a  manhole,  the  invert  or  bottom  of  the  smaller  drain  should  be 
higher  than  that  of  the  main  by  so  much  as  the  difference  between 
the  diameters  of  the  two,  so  as  to  prevent  the  liquid  flowing  in 
the  large  or  main  drain  from  backing  up  into  the  smaller.  By 
this  system  of  manhole  or  inspection-chambers,  the  drain — ■ 
which  runs  in  a  straight  line  from  manhole  to  manhole — can  be 
inspected,  and  cleared  by  rods  of  deposit  or  obstructions,  without 
breaking  into  it.  Where  it  is  necessary  to  connect  a  small  pipe 
with  a  larger  pipe,  the  junction  should  always  be  effected  by 
means  of  a  taper  or  diminishing  pipe. 

The  disconnection  of  the  house  drain  from  the  public  sewer  is 
generally  provided  for,  although  it  is  not  now  generally  held  that 
sewer   air  is   more  specially   harmful   than   drain   air.      Siphon 


io8 


HYGIENE    AND    PUBLIC   HEALTH 


disconnecting  traps,  however,  prevent  the  passage  of  sewer  rats 
up  the  house  drains ;  and  unless  such  traps  are  fixed,  it  would  be 
impossible  to  provide  for  the  ventilation  of  house  drains  by 
fresh  air  inlets  as  now  practised.  Disconnection  is  effected  by 
interposing  a  siphon  trap  between  the  house  drain  and  the  sewer, 
and  on  the  house  side  of  the  trap  a  means  of  inlet  for  fresh  air 
into  the  house  drain  is  provided.  The  point  usually  chosen  for 
disconnection  is  immediately  before  the  house  drain  leaves  the 
premises  in  its  course  to  the  street  sewer.     If  the  house  drain 


Section  of  Disconnecting  Chamber. 


A,  junction  45°  (4");  B,  junction  90°  (4");  C,  junction  30°  (4");  D,  main 
channel  (4")  ;  E,  intercepting  trap  (4"  to  6");  F,  clearing  eye;  G,  drain 
to  sewer  (6") ;  H,  drain  (4") ;  /,  fresh  air  inlet;  K,  galvanized  terminal ; 
L,  air-tight  cover;  71/,  condensing  dome;  N,  York  stone;  O,  glazed 
bricks,  or  preferably  brickwork  rendered  in  Portland  cement;  P,  con- 
crete; Q,  cement  ramps;  R,  cap  to  clearing  eye;  S,  water  joint  auto- 
matically sealed  by  condensation  ;  T,  ordinary  joint,  tallow  or  soft 
soap. 

is  provided  with  a  ventilating  pipe  at  the  further  end,  air, 
admitted  on  the  house  side  of  the  disconnecting  trap,  will  gene- 
rally travel  continuously  from  the  lower  opening  to  the  higher, 
and  a  circulation  will  thus  be  established  in  the  drain  and  soil 
pipe,  preventing  any  accumulation  of  foul  air. 

The  simplest  form  of  disconnecting  apparatus  consists  of  a 
siphon  trap  with  fresh  air  inlet  formed  of  stoneware  pipes  on 
the  house  side  of  the  water  seal.  There  are  several  varieties  of 
this  sort  of  trap  sold,  under  the  names  of  "  sewer  air  intercepter," 


DISPOSAL   OF    REFUSE  lOQ 

"  sewer  air  trap,"  etc.  The  points  to  be  observed  in  choosing 
a  trap  of  this  description  are:  (i)  Where  the  drain  is  a  6-inch  or 
a  9-inch  pipe,  the  siphon  should  be  a  size  smaller  than  the  drain; 
(2)  there  should  be  a  fall  of  2  inches  or  more  from  the  level  of  the 
discharging  end  of  the  house  drain  to  the  surface  of  the  trapping 
water;  (3)  the  siphon  should  provide  an  adequate  seal  of  2  or 
3  inches  of  water;  (4)  the  inlet  to  the  siphon  should  be  nearly 
vertical,  whilst  the  outlet  rises  at  an  angle  of  not  more  than  45°. 
These  qualities,  except  (3),  are  necessary  to  insure  sufficient 
flushing  of  the  trap ;  and,  to  further  attain  this  end,  the  drain 
should  be  laid  with  a  shghtly  greater  fall  before  its  junction  with 
the  trap.  The  fresh  air  inlet  to  the  siphon  is  continued  up  by  a 
vertical  pipe  to  a  little  above  the  surface  of  the  ground,  and 
there  co\ered  by  an  open  iron  grating,  which  may  be  guarded 
by  a  mica  flap  valve  to  prevent  any  escape  of  foul  air. 

There  is  no  doubt  that  the  odour  of  drain  and  sewer  gases  plays 
an  important  part  in  determining  injurious  effects  upon  health, 
for  rapid  and  profound  constitutional  disturbances  are  often 
induced  by  foul  odours,  the  effect  of  which  often  lasts  for  some 
time,  and  may  render  the  individual  specially  prone  to  certain 
infections.  Doubtless  the  short  length  of  house  drain,  with  its 
greater  fall,  generally  leads  to  that  pipe  keeping  cleaner  than 
the  long  common  pipe  or  sewer  into  which  it  discharges  ;  and 
since  the  offensive  sewage  gases  are  produced  in  proportion  to 
the  time  during  which  the  sewage  remains  in  the  pipe,  the  atmo- 
sphere of  sewers  is,  generally  speaking,  fouler  than  that  of  drains. 
Another  circumstance  favouring  the  retention  of  the  disconnect- 
ing trap  between  the  house  drain  and  the  sewer  is  that  the  faulty 
condition  of  stoneware  drains,  so  frequently  discovered,  is  re- 
sponsible for  the  fact  that  a  considerable  number  of  house  drains 
are  always  under  repair,  and  for  this  purpose  may  be  laid  open 
for  several  days  ;  the  dangers  to  the  occupants  would  be  increased 
if  during  these  occasions  the  drains  were  ventilating  the  sewer. 
It  is  claimed  that  without  using  intercepting  traps  the  gases  from 
the  sewer  would  be  distributed  by  escaping  through  the  drain 
and  soil  pipe  of  each  house  ;  but  no  such  equable  distribution  of 
escaping  gases  would  occur  in  a  district  of  varying  levels,  with 
houses  which  varied  a  great  deal  in  their  size,  height,  and 
proximity  to  the  sewer,  and  in  which  the  sewers  were  not  uni- 
formly sound  and  of  equal  gradient.  In  a  comparatively  flat 
district  with  a  recent  and  well-laid  system  of  sewerage,  or  in 


no  HYGIENE    AND    PUBLIC   HEALTH 

newly-developed  districts  in  which  iron  drainage  is  provided  for 
the  dwellings,  there  would  be  little  advantage  derived  by  inter- 
cepting the  house  drains  ;  but  if  the  intercepters  are  properly 
fixed,  of  a  good  type,  and  always  cleared  before  the  drainage  is 
covered  up,  they  very  rarely  give  rise  to  any  trouble. 

In  larger  houses  it  is  now  usual  to  provide  a  disconnecting 
manhole  chamber  (fig.  28),  instead  of  the  simple  trap  above 
described.  The  chamber  walls  are  built  of  brickwork  rendered 
in  cement,  and  the  floor  is  made  of  concrete.  Walls  lined  with 
glazed  brick  are  not  so  good  as  rendered  walls,  as  the  joints  in 
the  brickwork  are  apt  to  become  defective,  and  then  the  chamber 
is  no  longer  water-tight.  The  drain  is  continued  through  the 
floor  of  the  manhole  in  the  form  of  a  glazed  channel  pipe,  from 
which  the  floor — made  of  cement — slopes  up  (ramps  or  bench- 
ings)  at  an  angle  of  30°  to  the  brick  walls  of  the  manhole.  The 
branch  drains,  in  the  form  of  suitably  curved  (|  or  |)  glazed 
channel  pipes,  are  made  to  discharge  over  the  main  channel, 
which  itself  discharges  into  a  trap.  The  siphon  trap  should  be 
provided  with  a  "  raking  "  arm  or  clearing  eye,  one  end  of  which 
opens  into  the  manhole,  the  other  end  being  connected  with 
the  drain  beyond  the  trap.  This  arm  is  to  permit  of  obstruc- 
tions being  removed  from  the  drain  between  the  siphon  trap  and 
the  sewer;  when  not  in  use,  the  manhole  end  should  be  closed 
with  a  patent  stopper  or  a  tile  or  piece  of  slate  set  in  cement. 
The  manhole  chamber  may  be  closed  above  by  an  air-tight  iron 
cover;  and  the  fresh  air  should  then  be  admitted  into  the 
chamber  by  a  6-inch  pipe,  the  manhole  end  of  the  pipe  being 
opposite  the  entrance  of  the  drain,  whilst  the  end  open  to  the 
air  is  covered  by  an  iron  grating  and  provided  with  mica  flaps, 
which  permit  air  to  pass  in  but  prevent  the  reflux  of  foul  air. 
The  double  seal  condensing  cover  (fig.  28)  is  frequently  used 
where  the  manhole  chamber  must  be  built  inside  the  walls  of  a 
house.  Where  the  disconnecting  chamber  is  some  distance  from 
the  house  and  away  from  footpaths,  fresh  air  may  be  admitted 
by  perforations  in  the  iron  cover.  The  chief  advantage  of  the 
manhole  chamber  is  the  readiness  with  which  the  drain  can  be 
inspected  and  cleansed. 

Wherever  possible,  the  plan  of  drainage  should  be  so  designed 
as  to  provide  for  all  manhole  chambers  being  situated  in  yards 
or  openTareas,  and  not  actually  within  the  walls  of  the  house; 
for  tlicre  is  generally  some  danger  of  escape  of  drain  air  through 


DISPOSAL   OF    REFUSE  III 

covers  which  arc  not  perfectly  air-tight.  It  is  important  also 
that  the  interiors  of  manholes  should  be  rendered  in  cement,  so 
as  to  be  water-tight,  as,  if  the  disconnecting  trap  becomes  choked, 
the  chamber  may  become  filled  with  sewage. 

For  house  drains  with  insufficient  gradient,  in  which  deposit 
is  liable  to  occur,  it  is  advisable  to  provide  an  automatic  flush 
tank  to  discharge  into  a  gulley  at  the  head  of  the  drain ;  by  this 
means  the  dangers  arising  from  insufficient  fall  may  be  to  a  great 
extent  obviated.  Automatic  flush  tanks  should  be  fed  with 
clean  water  and  not  with  bath  or  other  dirty  waste  waters. 
Flush  tanks  fed  with  dirty  waste  waters  invariably  become  a 
nuisance. 

The  frequency  of  discharge  of  the  tank  can  be  regulated  by 
adjusting  the  tap  through  which  the  water  enters;  the  merest 
dribble  is  usually  quite  sufficient.  These  tanks  in  practice 
should  work  without  "  dribbling "  or  "  continuous  action," 
which  can  be  secured  by  fixing  them  on  a  perfectly  level  surface 
with  the  discharge  pipe  quite  plumb.  Flush  tanks  are  now 
usually  fitted  with  a  "  reversed  "  ball- valve.  When  the  ball 
is  depressed  in  the  tank  very  httle  water  passes  through  the 
valve ;  but  when  the  tank  is  very  nearly  full  the  valve  is  fully 
opened,  a  rush  of  water  enters  the  tank,  and  siphonage  at  once 
takes  place.  Dribbling  and  continuous  action,  which  are  some- 
times due  to  smallness  of  flow  into  the  tank,  are  thus  avoided, 
whilst  the  time  of  filling  the  tank  can  still  be  regulated  as  desired. 

All  waste  pipes  from  baths,  lavatories,  sinks,  and  safe-trays 
under  water-closets  or  baths  must  be  disconnected  from  the 
drain  or  soil  pipe  by  being  made  to  discharge  into  the  open  air. 
The  waste  pipes  from  baths,  lavatories,  and  sinks  should  be 
of  a  large  diameter  (i|  or  2  inches)  to  insure  rapid  emptying 
of  the  baths,  sinks,  etc.,  and  as  short  as  possible,  for  they  tend 
to  become  coated  internally  with  a  deposit  of  dirt  and  soap, 
which  decomposes  and  may  be  productive  of  nuisance.  To 
prevent  foul  air  from  these  pipes  entering  the  house,  a  cast- 
lead  siphon  trap  should  be  fixed  under  every  bath,  lavatory, 
and  sink;  and  in  the  case  of  kitchen  sinks  this  siphon  trap 
should  be  provided  at  its  lowest  point  with  a  screw  cap,  capable 
of  removal,  in  order  to  clear  the  trap  of  sediment  and  grease. 
The  waste  pipes  from  the  upper  floors  are  often  carried  through 
the  external  walls  to  discharge  into  the  open  head  of  a  rain-water 
pipe  divided,  if  necessary,  into  lengths  for  this  purpose;  but 


112  HYGIENE   AND    PUBLIC    HEALTH 

this  is  not  a  very  good  plan  if  the  open  heads  are  an57where 
near  windows,  for  the  iron  pipes  become  in  course  of  time 
much  fouled  from  soap  and  dirt,  and  then  are  apt  to  smell 
offensively.  In  such  cases  the  2-inch  lead  waste  pipe  should 
be  continued  down  to  the  gulley  at  the  ground  level,  its  upper 
end  being  carried  up  to  the  roof  and  left  open;  anti-siphonage 
pipes  will  usually  be  required  in  the  cast  of  bath  and  lavatory 
wash-hand  basin  waste  pipes,  to  prevent  siphonage  of  traps, 
especially  where  several  waste  pipes  on  different  floors  discharge 
into  a  main  waste  pipe.  Every  rain-water  or  waste  pipe  must 
be  disconnected  from  the  drain  at  its  foot  by  opening  over  or 
under  the  iron  grating  over  a  stoneware  siphon  yard  gulley. 
The  basement  waste  pipes  may  discharge  into  yard  gulleys  by 
side  inlets.  When  it  is  impossible  to  avoid  having  a  long  waste 
pipe,  this  must  be  ventilated  by  a  pipe  of  its  own  diameter  carried 
up  outside  the  house  to  a  convenient  point.  Whenever  it  is 
necessary  to  place  waste  or  other  pipes  within  partitions  or 
recesses  in  walls,  they  should  never  be  covered,  except  with 
woodwork,  which  should  always  be  made  readily  removable. 

The  surface  water  from  yards  and  areas  should,  where  possible, 
be  carried  off  by  those  siphon  gulleys  which  receive  the  waste 
waters  from  the  house,  because  these  gulleys  are  always  efficiently 
trapped  in  dry  weather.  Yard  gulleys  used  for  surface  water 
only  become  untrapped  in  dry  weather,  owing  to  the  evaporation 
of  the  water  in  them.  These  gulleys  for  waste  and  surface  water 
are  connected  with  branch  drains  which  join  the  main  drain 
in  the  inspection  or  manhole  chambers  before  referred  to;  they 
require  to  be  cleansed  periodically  of  sand  and  dirt,  which  collect 
at  the  bottom  of  the  trap. 

In  large  houses  it  is  found  that  the  sand  and  grease  discharged 
through  the  kitchen  or  scullery  sink  are  apt  to  lodge  in  the  drain 
from  the  gradual  solidification  of  the  grease  as  the  water  cools, 
and  so  form  an  obstruction.  It  is  usual  in  such  cases  to  cause 
the  waste  pipe  (2-inch  pipe,  trapped  under  the  sink)  to  discharge 
into  a  grease  gulley  instead  of  into  a  yard  gulley.  This  grease 
gulley  is  made  of  stoneware,  and  may  with  advantage  be  con- 
nected with\an  automatic  siphon  flush  tank  (fig.  29).  The  hot 
water  from  ^he  sink  is  cooled  on  entering  a  large  volume  of 
cold  water  in  the  trap,  the  grease  solidifies  and  rises  to  the 
top,  whilst  th(t  sand  sinks  to  the  bottom  of  the  trap.  When  the 
flush  tank  discharges,  the  grease  is  thoroughly  broken  up  by  the 


DISPOSAL   OF   REFUSE 


113 


sudden  inrush  of  the  large  volume  of  water,  and  is  then  carried 
along  through  the  drain  without  any  opportunity  being  given  to 
it  to  deposit  on  the  sides  or  floors  of  the  pipes.  The  grease  gulley 
should  be  covered  above  by  a  grating,  and  sunk  a  httle  beneath 


DRAIN 

Fig.  29. — Flushing  Grease  Gulley. 


the  surface  of  the  adjoining  ground  to  confine  all  splashings  to 
the  trap. 

To  carry  off  the  water  used  for  washing  down  laundries, 
sculleries,  and  dairies,  the  floors  should  slope  to  a  channel  leading 
to  a  yard  gulley  outside  the  house. 


114 


HYGIENE   AND    PUBLIC    HEALTH 


The  house  drainage  arrangements  described  above    have  for 
their  object:  (i)  The  speediest  possible  removal  from  the  house 


RWP 


B 


Fig.  30. — Semi-detachkd  IIol'ses. 

A,  modern  drainage;  B,  old  drainage  system ;  D.C..  disconnecting  chamber; 
F.A.I.,  fresh  air  inlet;  I.C.,  inspection  chamber;  S.P.,  soil  pipe; 
G.,  guUey;  S.,  sink;   R.W.I'.,  rain-vvutcr  pipe;  W.C,  water -closet. 

to  the  public  sewer  of   excretal  and  other  refuse  by  means  of 
water;  {2)  the  prevention  of  deposit  of  foul  matter  in  any  part  of 


DISPOSAL   OF   REFUSE  II5 

the  drainage  system,  and  of  percolation  into  the  soil  of  polluting 
liquids;  (3)  the  estabhshment  of  a  current  of  air  through  every 
part  of  the  soil  drains  and  pipes,  in  order  to  disperse  any  foul 
gases  that  may  form,  and  allow  them  to  escape  with  safety 
into  the  open  air;  (4)  the  prevention  of  any  entry  of  gases  from 
soil  pipes,  drains,  and  waste  pipes,  into  the  house;  (5)  the 
exclusion  of  the  air  of  the  common  sewer  from  the  house  drain 
and  the  house. 

Objects  (4)  and  (5)  are  to  a  great  extent  attained,  as  we  have 
seen,  by  means  of  traps  or  water  seals,  and  the  question  arises, 
"  How  far  do  such  traps  carry  out  the  objects  for  which  they 
are  designed  ?"  Siphon  traps  are  the  most  cleanly  of  all  traps, 
because  they  present  no  corners  or  angles  where  deposit  can 
accumulate,  and  are  most  easily  flushed  clean.  Their  liability 
to  siphonage  we  have  considered,  and  we  have  endeavoured  to 
show  that  it  can  be  obviated  by  a  sufficient  depth  of  siphon, 
providing  an  efficient  seal  of  water,  and  by  adequate  ventilation. 
There  is,  however,  another  disadvantage  common  to  all  water 
traps,  which  is  that  the  water  may  absorb  gases  on  one  side  of 
the  trap,  and  give  them  off  on  the  other,  so  that  foul  air  from  the 
drain  or  sewer  may  be  given  off— only,  however,  to  an  inconsider- 
able extent — into  a  house,  notwithstanding  the  presence  of  the 
trap.  The  only  remedy  for  such  a  state  of  things  is  the  pre- 
vention of  foul  air  accumulations  by  adequate  ventilation.  The 
proper  ventilation  of  drains  and  soil  pipes  can  only  be  effected 
where  there  is  an  inlet  for  fresh  air  at  one  end  of  the  system, 
and  an  outlet  for  foul  air  at  the  other  end.  Where  there  is  an 
outlet  but  no  inlet,  the  pipes  must  be  always  full  of  foul  air, 
though  not  under  pressure,  for  there  can  be  then  no  renewal  of 
the  air  in  them  by  the  passage  of  fresh  air  currents. 

The  Testing  of  Drains  and  Soil  Pipes  and  their  Branches. 

Tests  are  employed  for  new  sanitary  work,  during  tlie  progress  of  the 
work,  to  ascertain  tbiat  it  is  being  properly  constructed,  and  also  for 
sanitary  works  that  have  been  in  existence  for  some  time,  to  ascertain 
if  the  work  is  still  sound.  The  principal  tests  are  the  water  or 
hydraulic  test,  the  smoke  test,  the  pneumatic  or  air  test,  and  the  chemical 
test. 

The  Water  Test. — This  test  is  now  almost  invariably  employed  for  new 
drainage  work,  and  is  applied  after  the  drains  are  laid  and  jointed,  but 
before  they  are  embedded  in  concrete,  or  before  the  drain  trenches  are 
filled  in.  The  lower  end  of  the  drain,  as  it  enters  the  disconnecting  cham- 
ber, is  plugged  by  means  of  an  expanding  screw  plug  with  rubber  rim  of  the 
size  appropriate  to  the  drain,  or  by  means  of  a  strong  canvas  bag,  which 
can  be  filled  with  air  under  pressure  by  means  of  an  air  force-pump.     As 


Il6  HYGIENE   AND   PUBLIC   HEALTH 

soon  as  the  drain  is  securely  plugged,  and  a  cord  has  been  attached  to  the 
plug  to  prevent  its  being  carried  away  when  the  water  is  released,  water  is 
allowed  to  How  into  the  upper  portion  of  the  system  until  it  has  risen  to  the 
top  of  an  inspection  chamber  or  guUey  at  the  head  of  the  drain.  If,  after 
stopping  the  flow,  the  water  level  remains  stationary  for  some  minutes,  the 
drainage  system  under  test  is  sound;  but  should  the  water-level  fall,  there 
is  a  defect  at  some  point,  and  the  joints  of  the  drain  should  be  carefully 
examined  for  evidence  of  leakage.  It  is  important  to  remember  that  in 
thus  applying  the  test  to  a  system  of  drains,  air  will  be  imprisoned  in  the 
branch  drains  leading  from  guUeys  or  water-closets,  if  the  latter  are  charged 
with  water.  This  air  is  liable  to  become  slowly  absorbed  by  the  water, 
when  compressed,  and  thus  lead  to  a  fall  in  the  general  level  of  the  water, 
although  the  drains  may  be  sound.  The  imprisoned  ah  should  be  allowed 
to  escape  by  passing  a  bent  pipe  through  the  water  of  the  trap  that  retains 
the  air. 

In  drains  of  considerable  length  with  steep  gradients  the  head  of  water 
pressure  in  the  lowest  section  of  the  drain  may  be  considerable;  but  in 
testing  house  drains,  at  any  rate,  nothing  approaching  a  bursting  strain 
for  well  made  and  well  jointed  stoneware  drains  is  liable  to  be  reached. 
In  testing  the  drains  of  very  large  establishments,  however,  the  system 
should  be  tested  in  sections,  and  any  general  test  which  would  place  undue 
strains  upon  the  pipes  and  joints  should  be  avoided. 

In  applying  the  water  test  to  existing  drainage,  the  same  methods  are 
applicable;  but  should  a  general  test  show  leakage,  it  will  be  necessarj'  to 
test  in  sections  until  the  leak  is  sectionally  located.  There  is  no  diffi- 
culty in  carrying  this  out,  if  there  are  the  proper  proportion  of  inspection 
chambers,  as  branch  drains  can  be  plugged  in  the  inspection  chambers 
to  which  they  are  connected  at  one  end,  and  tested  with  water  up  to  the 
levels  of  the  tops  of  the  guUeys  or  water-closets  with  which  they  are 
connected  at  the  other.  Inspection  chambers,  which  are  very  often  found 
to  be  leaky  from  defective  rendering  with  cement,  can  be  treated  separately 
by  tilling  with  water,  after  all  drains  entering  or  leaving  them  have  been 
securely  plugged.  It  sometimes  happens  that  an  old  drain  is  found  to  be 
in  a  very  dirty  condition,  but  water-tight  on  testing.  After  the  drain  has 
been  rodded  and  cleansed,  on  further  testing,  it  may  be  found  to  be  no 
longer  water-tight,  owing  to  the  grease  and  tilth  which  sealed  the  interiors 
of  defective  joints  being  washed  away  in  the  process  of  cleansing. 

In  old  drainage  systems  without  any  inspection  chambers  the  water 
test  cannot  be  applied  unless  the  drain  is  exposed  at  some  point  (usually  at 
or  near  its  lower  end),  and  a  pipe  removed  in  order  that  the  plug  may  be 
inserted.  Old  drains  of  this  description  are  very  seldom  found  to  be 
water-tight ;  and  it  has  been  said  that  the  application  of  the  water  test  to  an 
old  drain  is  liable  to  damage  it  and  open  up  the  joints.  It  is  very  doubtful, 
however,  if  the  water  test  carefully  applied  ever  does  any  injury  of  this 
sort  even  to  an  old  drain.  Any  soil  drain  passing  under  or  quite  near  to  a 
house  should  be  sufficiently  sound  to  pass  a  water  test. 

Vertical  soil  pipes  and  then  water-closet  branches  may  be  tested  with 
water,  before  the  w.c.'s  are  connected,  by  soldering  over  the  apertures 
where  the  closet  apparatus  is  connected,  and  then  filling  with  water,  alter 
plugging  the  lower  end  of  the  soil  pipe,  or  the  branch  drain  from  the  soil 
pipe  in  the  nearest  inspection  chamber.  This  is  a  severe  test,  if  there  is  a 
great  head  of  water,  and  one  but  rarely  applied,  yet  it  is  withstood  by  a 
good  lead  soil  pipe  with  strong  wiped  joints. 

The  Ball  Test. — This  is  applied  to  new  drainage  work,  before  the  drains 
art  covered  in,  to  ascertain  that  there  arc  no  projections  of  cement  from 
tin;  joints  into  the  interior  of  the  drain,  by  passing  a  spherical  wooden  ball, 
\  inch  less  in  diameter  than  the  drain,  through  the  pipes  from  the  upper  to 
the  lower  end. 


DISPOSAL   OF    REFUSE  II7 

The  Smoke  Test. — This  test  is  applied  either  by  means  of  a  smoke  rocket 
or  by  a  smoke  machine.  The  test  is  usually  applied  to  both  underground 
drains  and  vertical  soil  pipes,  or  drain  ventilating  pipes,  at  the  same  time. 
The  disconnecting  chamber,  or  inspection  chamber  at  the  lowest  point  of 
the  drain,  is  uncovered,  and  the  smoke  rocket  after  ignition  is  inserted  into 
the  drain  delivering  into  the  chamber.  The  rush  of  smoke  from  the  rocket 
forces  the  air  upwards  through  the  drain,  and  where  there  is  a  good  upward 
draught,  the  smoke  will  shortly  be  observed  issuing  from  the  top  of  the  soil 
pipe  or  the  drain  ventilator.  As  soon  as  the  smoke  issues  freely  from  the 
outlet,  this  should  be  closed  by  means  of  a  plug  or  by  a  wet  cloth,  and  at 
the  same  time  the  drain  should  be  plugged  where  the  rocket  is  inserted, 
or  the  cover  to  the  inspection  chamber  should  be  replaced  to  prevent 
reflux  of  smoke  at  this  point.  In  this  way  the  whole  length  of  drain  and 
soil  pipe  and  soil-pipe  ventilator  can  be  charged  with  smoke  confined  under 
very  slight  pressure.  If  there  are  any  defects  in  the  pipes  or  in  their  joint- 
ing, smoke  will  escape  at  such  points,  and  will  generally  make  itself  evident 
either  to  sight  or  smell,  according  as  to  whether  the  defect  is  exposed  to 
view  or  concealed  beneath  the  ground  or  in  walls  and  casings.  In  carrj'ing 
out  the  smoke  test,  particular  care  is  necessary  to  ensure  that  all  traps 
connected  with  the  drain  or  soil  pipe  under  test  are  properly  charged  with 
water,  and  that  doors  and  windows  facing  the  spot  at  which  the  test  is 
being  applied  are  carefully  closed. 

In  the  smoke  machine,  air  is  forced  by  means  of  a  bellows  through  a  metal 
compartment  containing  smouldering  paper  or  cotton  waste  well  saturated 
with  oil,  and  a  flexible  pipe  from  the  machine  leads  the  smoke  into  the  drain 
or  soil  pipe.  The  machine  is  rather  cumbersome  to  carry  about,  but  has  the 
advantage  over  smoke  rockets  that  the  test  may  be  applied  under  a  definite 
pressure  of  about  i  to  2  inches  of  water,  and  that  the  flexible  pipe  can  be 
passed  through  gulleys  or  traps  on  the  line  of  a  drain,  where  inspection 
chambers  do  not  exist,  or  the  test  can  be  applied  from  the  top  of  the  soil- 
pipe  ventilator  in  the  reverse  manner  to  that  usually  employed  with  rockets, 
where  this  method  is  more  convenient.  The  test  with  the  smoke  machine 
is  carried  out  in  the  same  way  as  previously  described  for  rockets.  In 
either  case,  where  there  is  no  disconnecting  chamber  to  the  drain,  the  water 
seal  in  the  gulley  trap  which  is  nearest  to  the  outlet  of  the  drain  is  generally 
removed,  and  the  smoke  rocket,  or  the  tube  of  the  smoke  machine,  is 
inserted  into  the  bend  of  the  trap.  In  doing  so,  however,  there  is 
always  a  possibility  that  the  smoke  will  pass  directly  into  the  sewer, 
and  not  traverse  the  house  drain,  owing  to  the  absence  of  a  disconnecting 
trap. 

The  smoke  test  is  better  evidence  of  defects  in  vertical  soil  pipes  and 
ventilating  pipes  than  of  defects  in  underground  drains;  as,  in  the  case  of 
the  latter,  although  defects  may  exist,  the  issuing  smoke  may  not  reach 
the  surface  of  the  ground  or  find  its  way  to  any  point  at  which  it  could 
be  detected  either  by  sight  or  smell.  Escapes  from  vertical  pipes  are 
usually  readily  detected. 

The  Pneumatic  or  Air  Test. — This  is  very  similar  to  the  smoke  test  as 
applied  bv  a  smoke  machine,  air  being  forced  by  means  of  an  air  pump  into 
the  drain  or  soil  pipe  after  the  top  of  the  soil  pipe  or  other  drain  ventilating 
pipes  have  been  securely  plugged.  A  water  gauge  attached  to  the  pneu- 
matic machine  shows  the  pressure  in  inches  of  water;  and  if  this  pressure 
is  maintained  for  a  few  minutes,  it  is  evident  that  the  system  under  test 
is  air-tight.  The  nozzle  of  the  machine  passes  through  an  expanding  screw 
plug  or  pneumatic  bag,  which  makes  an  air-tight  joint  with  the  drain 
or  pipe  into  which  the  nozzle  is  inserted.  The  test  is  a  severe  one,  as  the 
very  smallest  pin-hole  defect  will  present  an  aperture  for  the  escape  of  air, 
sufficient  to  prevent  a  pressure  of  an  inch  of  water  being  maintained  with 
the  pipes  under  test.     It  suffers  also  from  the  drawback  that  there  is 


Il8  HYGIENE   AND   PUBLIC   HEALTH 

nothing  to  indicate  the  exact  position  ol  the  defect,  since  the  escaping  air 
i^;  both  colourles'5  and  odourless. 

The  Cliemical  Test. — This  is  usually  applied  by  means  of  grenades  or 
small  glass  capsules  containing  a  composition  of  phosphorus  and  asaf  cetida. 
When  the  containing  glass  is  broken  and  the  composition  comes  into  contact 
with  water,  a  slight  explosion  takes  place,  and  dense  white  fumes  having 
the  characteristic  smell  of  asafcetida  are  evolved.  These  fumes  escape 
through  defects  in  the  drain  or  pipes,  and  so  give  evidence  of  leakages, 
which  are  recognized  bv  the  sense  of  smell.  In  testing  underground  drains 
by  this  method  a  certain  time  (i  5  to  30  minutes)  should  be  allowed  to  elapse 
before  deciding  that  there  is  no  evidence  of  defects,  as  the  odour  may  take 
a  considerable  period  to  travel  from  the  defective  drain  to  any  point  at 
which  its  presence  could  be  appreciable.  In  using  the  grenades,  one  or 
two  may  be  wrapped  up  in  blotting  paper,  broken  by  a  sharp  tap,  and  then 
thrown  into  the  w.c.  basin  on  the  highest  floor,  the  basin  being  immediately 
flushed,  so  as  to  carry  the  broken  capsules  to  the  drain  side  of  the  w.c. 
trap;  or  the  same  result  may  be  attained  in  Kempe's  apparatus,  the 
grenade  or  capsule  being  floated  through  the  trap  of  the  w.c,  and  then 
broken  by  a  sharp  pull  on  a  string  which  releases  a  spring. 

There  is  a  method  of  repairing  leaky  drains,  in  situ,  without  opening 
the  ground,  which  may  be  applied  in  suitable  cases.  The  drain  is  first 
cleansed,  and  then  a  small  apparatus  containing  Portland  cement  under 
pressure  is  passed  several  times  through  the  drain.  As  the  apparatus 
passes  any  leaky  point  in  the  drain, the  liquid  cement  escapes  at  this  point 
and  fills  the  leaky  joint,  etc.  Time  is  then  allowed  for  the  cement  to 
partially  set,  when  a  swab  is  drawn  through  the  drain  to  remove  any 
projecting  pieces  of  cement.  The  drain  is  thus  treated  in  sections,  which 
are  temporarily  disconnected,  and  finally  a  water  test  is  applied  to  the 
whole.  For  old  and  defective  drains  from  which  there  has  been  much 
leakage  it  is  more  sanitary,  and  often  more  economical,  to  remove  the  old 
pipes  and  the  contaminated  earth  surrounding  them,  and  to  replace  with 
sound  pipes  and  clean  earth. 

Stables. 

The  proper  paving  and  drainage  of  stables  is  important,  as 
dampness  and  foul  air  are  very  injurious  to  the  health  of  horses. 
The  floors  of  stables  should  be  paved  with  a  small  hard  brick, 
such  as  that  known  as  adamantine  clinker,  with  chamfered  edges 
set  in  cement,  such  bricks  being  impervious  to  water  and  small 
enough  to  give  a  foothold  to  the  animals.  The  floor  should  have 
a  gentle  slope  of  about  i  inch  in  10  feet,  from  the  heads  of  the 
stalls  towards  a  cement  drainage  channel  constructed  to  convey 
liquids  outside  the  stable  to  a  gulley  in  the  stable  yard.  These 
channels  should  be  covered  with  iron  gratings  flush  with  the 
floor,  easily  detachable  for  the  purpose  of  cleansing.  If  horse 
and  mare  pots  are  considered  preferable  to  channels,  they  should 
be  connected  to  drains,  which  are  led  outside  the  stable  to  dis- 
charge into  the  back  or  side  inlet  of  a  deep  gulle3^  Inasmuch  as 
a  good  deal  of  straw  or  other  material  used  for  litter  is  apt  to  pass 
away  with  the  stable  drainage,  the  gulley  receiving  those  liquids 


DISPOSAL   OF   REFUSE 


119 


should  be  a  Dean's  silt  gullcy  with  removable  bucket  for  collecting 
solid  particles  {vide  fig.  31). 

For  storing  stable  manure,  whilst  awaiting  removal,  the  best 
receptacle  is  an  open  wire  cage,  which  allows  the  free  play  of  air 
over  the  surface  of  the  refuse,  and  thus  prevents  heating  and 
fermentation  in  the  interior.  Sunken  dung  pits  are  generally  a 
nuisance,  as  they  favour  fermentative  changes;  they  should  be 
abolished  in  favour  of  open  wire  cages  resting  on  a  cemented 
surface  in  the  stable  yard. 

Peat  moss,  dried  and  compressed,  is  now  largely  used  as  litter 
instead  of  straw,  especially  in  cab  and  omnibus  yards.  It  is 
more  absorbent  than  straw,  and 
consequently  keeps  the  stables 
where  it  is  in  use  very  dry.  If 
used  too  long,  it  becomes  highly 
impregnated  with  urine,  and  gives 
off  most  offensive  effluvia.  In  cab 
and  omnibus  yards  the  peat  moss 
manure  is  generally  very  rank  and 
stale  before  it  is  removed  from 
the  stable,  and  when  stacked  in 
heaps  and  subsequently  thrown 
up  into  carts,  the  nuisance  is  very 
great.  It  is  in  these  cases  especi- 
ally that  carts  or  vans  should 
be  used  to  receive  the  manure 
directly  as  it  issues  from  the  stalls  of  the  stables,  so  that  when 
the  van  is  filled  it  can  be  drawn  away  without  further  disturbance. 

Mines. 

Although  many  conditions  are  imposed  which  aim  at  safe- 
guarding the  miners  of  this  country  from  accidents,  and  although 
much  has  been  done  in  recent  years  to  diminish  the  incidence  of 
pulmonary  complaints  among  miners  by  reducing  dust  and 
noxious  gases  arising  from  drilling  and  blasting  operations, 
comparatively  little  has  been  done  in  reference  to  those 
other  sanitary  precautions  which  are  necessary  in  order  to 
guard  against  the  risks  of  spread  of  enteric  fever  and  ankylo- 
stomiasis. 

That  the  danger  which  the  miner  runs  of  infection  of  enteric 
fever  is  real,  and  at  times  leads  to  outbreaks  of  disease  in  this 


Fig.  31. — Dean's  Silt  Gulley. 

A,  Cast-iron  receptacle  to  lift 

in  and  out. 


120  HYGIENE   AND   PUBLIC   HEALTH 

country,  is  testified  by  certain  reports  of  medical  inspectors  of 
the  Local  Government  Board. 

The  reports  upon  ankylostomiasis  in  Westphalia  and  elsewhere 
provide  almost  a  voluminous  literature  on  the  prevalence  of  this 
disease  in  hot,  damp  mines;  and  among  the  most  valuable  of 
these  reports,  and  one  which  has  also  a  topical  interest,  is  Dr 
Haldane's  Report  to  the  Home  Secretary  on  an  outbreak  of  the 
disease  in  a  Cornish  mine,  where  ankylostomiasis,  though  abated, 
still  exists. 

The  sanitary  conditions  underground  have  often  been  demon- 
strated to  favour  the  spread  of  both  of  these  diseases,  and  it 
is  alike  in  the  interests  of  mine  owners  and  miners  that  more 
precautions  should  be  taken  to  guard  against  them.  The  capital 
expenditure  involved  would  return  a  satisfactory  rate  of  interest 
by  maintaining  a  higher  level  of  production. 

A  mine  that  would  satisfy  the  full  demands  of  hygiene  in 
respect  of  the  danger  associated  with  miners'  excreta  should  have 
sufficient  and  suitable  provision  in  the  workings  for  the  collection, 
removal,  and  disposal  of  all  dejecta.  It  should  be  remarked 
here,  however,  that  in  the  case  of  coal  mines,  where  the  bed  is 
approximately  horizontal,  there  is  Httle  objection  to  the  use  of 
the  "  goaves  "  or  "  wastes."  Miners  should  reahze  the  import- 
ance of  taking  suitable  precautions  underground  with  reference 
to  their  dejecta;  they  should  also  endeavour  to  acquire  the 
habit  of  defaecating  morning  or  evening  before  descending,  so  far 
as  possible,  and  should  only  defaecate  below  when  really  neces- 
sary; and  in  order  to  promote  this  practice  privies  or  water- 
closets  should  be  provided  near  the  pit  mouth.  Miners  should 
be  informed  of  the  necessity  of  being  careful  with  reference  to 
the  food  consumed  underground;  this  should  be  kept  covered  in 
tin  cans  or  paper  and  only  handled  through  paper,  and  the  hands 
should  be  kept  out  of  contact  with  the  mouth.  The  men  should 
wash  and  change  clothes  before  partaking  of  food  upon  their 
return  home  after  work,  and  to  promote  this  practice  spray  baths 
and  dressing-rooms  should  be  provided  near  the  pit  mouth. 
Miners  very  rarely  drink  any  mine  water  (except  in  some  excep- 
tional circumstances  abroad) ;  they  take  their  drink  down  into 
the  mine  with  them;  but  the  men  should  realize  that  under  no 
circumstance  is  it  safe  to  drink  mine  water,  and  that  if  such  water 
is  used  for  rinsing  the  hands  it  can  never  sufficiently  cleanse  them. 
Stagnant  water  in  the  workings  should  be  reduced  to  a  mini- 


mSPOSAT.    OF    REFUSE  121 

mum ;  and  where  there  is  running  water  the  channels  should 
be  kept  clear  and  the  water  not  allowed  to  "  pond  "  in  places 
through  waste  matter  blocking  up  the  channels. 

No  new  hand  should  be  employed  without  previous  medical 
inspection,  and  a  careful  inquiry  into  his  previous  infectious 
disease  history.  If  he  has  recently  had  enteric  fever,  or  if  there 
is  a  possibility  that  he  may  be  harbouring  the  ankylostoma,  his 
dejecta  should  be  first  examined  bacteriologically ;  and  all  cases 
of  illness  should  be  promptly  reported  to  the  manager  or  agent. 
Provision  should  be  made  at  the  nearest  bacteriological  labora- 
tory for  samples  of  dejecta  to  be  examined. 

The  special  rules  relating  to  the  dejecta  which  have  been  made 
under  the  Metalliferous  Mines  Regulation  Acts,  1872  and  1875, 
are  to  the  following  effect : — 

(5)  The  owner,  agent,  or  manager  shall  cause  a  sufficient  number  of 
suitable  sanitary  conveniences  to  be  provided  above  and  below  ground  in 
convenient  places  for  the  use  of  the  persons  employed,  and  to  be  constantly 
kept  in  a  cleanly  and  sanitary  condition,  and  no  person  shall  relieve  his 
bowels  below  ground  elsewhere  than  in  those  conveniences.  No  person 
shall  soil  or  render  unfit  for  use  in  any  way  any  convenience  or  sanitary 
utensil  or  appliance  provided  for  the  use  of  the  persons  employed.  Pump 
cisterns,  sumps,  and  water  accumulations  in  the  mine  shall  not  be  in- 
directly used  for  the  purpose  of  a  sanitary  convenience. 

(6)  It  shall  be  the  duty  of  the  owner,  agent,  or  manager  to  see  that 
plant,  material,  and  other  things  necessary  to  enable  the  above  rule  to  be 
carried  out  are  provided  and  maintained  in  working  order,  and  to  appoint 
sufficient  competent  officials  to  enforce  the  requirements  of  the  rules,  and 
for  this  purpose  to  assign  to  each  his  respective  duties. 

Sewers. 

Sewers  are  underground  channels  designed  to  receive  and 
convey  away  by  gravitation  the  rainfall  and  waste  waters  of  the 
town,  and,  where  the  water-carriage  system  has  been  adopted, 
excretal  refuse  as  well.  In  former  times,  and  in  some  towns  at 
the  present  day,  if  a  river  or  stream  passed  through  or  near  a 
town,  the  sewers  took  the  shortest  available  course  to  the  banks 
of  the  stream,  and  there  discharged — each  sewer  by  its  own  out- 
fall. When  it  became  no  longer  possible  for  towns  to  discharge 
their  crude  sewage  into  streams  in  this  manner,  intercepting 
sewers  of  large  size  had  to  be  constructed  to  receive  the  sewage 
of  the  tributary  sewers  and  conduct  it  outside  the  town. 

As  we  have  already  seen,  brick  sewers,  as  originally  con- 
structed, perform  a  double  function;  they  are  land  drains  as 
well  as  sewers.     By  permanently  lowering  the  level  of  the  subsoil 


122  HYGIENE   AND    PUBLIC    HEALTH 

water  in  towns,  these  sewers  have  had  an  important  effect  in 
improving  the  health  of  the  inhabitants. 

But  the  beneficial  influence  of  sewers  acting  as  drains  has  an 
undoubted  drawback,  viz.,  that  drain  sewers  will  readily  permit 
of  foul  liquids  percolating  out  of  them,  through  their  walls,  to 
pollute  the  surrounding  soil  and  contaminate  ground  water  and 
ground  air  in  the  neighbourhood.  That  such  escape  of  foul 
water  does  take  place  is  plainly  shown  by  the  fact  that  in  London, 
with  its  drain  sewers,  all  shallow  well  waters  have  been  found  to 
be  polluted  with  sewage,  and  the  wells  have  in  consequence  been 
closed.  It  is  now  the  practice  of  all  engineers  to  construct  sewers 
as  far  as  possible  water-tight,  and  to  provide  other  means  for 
draining  the  soil. 

The  Combined  System. — In  this  system  the  sewers  are  designed 
to  receive  the  rain — or  such  part  of  it  as  does  not  evaporate  or 
is  not  retained  by  the  soil — falling  over  the  area  covered  by  the 
town,  as  well  as  the  sewage  proper.  The  amount  of  evaporation 
depends  largely  on  the  temperature  of  the  air;  but  even  in 
summer  it  is  found  in  towns,  where  a  large  part  of  the  surface 
exposed  to  rainfall  consists  of  roofs  and  paved  surfaces  of  yards, 
courts,  and  streets  (especially  also  where  there  are  steep 
gradients),  that  from  one-half  to  three-quarters  of  the  rain  falUng 
reaches  the  sewers.  It  is  therefore  necessary  to  construct  the 
sewers  of  sufficient  size  to  take  a  large  part  of  the  rain  falling 
during  heavy  storms,  such  as  |  inch  of  rain  in  one  hour  in  towns, 
and  J  to  l^  inch  in  the  suburbs;  otherwise,  if  no  storm  overflows 
are  provided,  the  sewers  in  low-lying  districts  are  overcharged, 
and  cellars  and  basements  are  flooded.  In  London  the  inter- 
cepting sewers  were  constructed  to  receive  \  inch  of  rain  over 
the  whole  area  sewered  in  twenty-four  hours  (including  subsoil 
water) ;  but  storm  overflows  direct  into  the  Thames  relieve  these 
sewers  during  heavy  storms.  When  a  storm  occurs  after  a  time 
of  drought,  the  sewers  are  flushed  of  accumulated  deposit,  and 
the  sewage  which  first  escapes  by  the  storm  overflows  is  often 
very  strong  and  foul,  and  productive  of  nuisance  in  the  river. 
At  high-water,  too,  the  storm  overflows  are  tide  locked,  and 
then  low-lying  districts  may  be  flooded. 

This  principle  of  the  interception  of  sewage  is  also  commonly 
practised  in  seaside  towns  where  the  original  sewers  have  been 
given  a  direct  course  to  the  sea,  and  the  escaping  sewage  gave 
rise  to  offence.     The  intercepting  sewer  running  along  the  sea- 


DISPOSAL   OF   REFUSE  12.3 

shore  picks  up  the  original  sewers,  and  conveys  the  sewage  to 
its  outlet  some  distance  away  from  the  town.  Such  a  main 
outfall  sewer  discharging  into  the  sea  should  terminate  below 
the  water-level,  even  at  low  tide,  and  should  have  the  outlet 
protected  by  a  flap  valve. 

To  prevent  deposits,  sewers  should  be  rendered  self-cleansing 
by  being  constructed  with  a  sufficient  gradient,  and  of  a  size 
suitable  to  the  volume  of  sewage  which  they  will  ordinarily  be 
required  to  carry.  According  to  Mr.  Baldwin  Latham,  sewers 
of  from  12  to  24  inches  diameter  should  have  a  gradient  sufficient 
to  produce  a  velocity  of  not  less  than  2 J  feet  per  second,  and 
in  sewers  of  larger  dimensions  in  no  case  should  the  velocity 
be  less  than  2  feet  per  second.  For  large  sewers  a  less  gradient 
is  required  than  for  small  sewers  to  produce  the  same  velocity; 
but  the  volume  of  the  sewage  to  be  conveyed  must  be  very  much 
greater  for  the  large  than  for  the  small  sewer.  A  sewer  10  feet 
in  diameter  having  a  fall  of  2  feet  per  mile;  a  sewer  5  feet  in 
diameter  having  a  fall  of  4  feet  per  mile;  a  sewer  2  feet  in 
diameter  having  a  fall  of  10  feet  per  mile ;  and  a  sewer  i  foot  in 
diameter  with  a  fall  of  20  feet  per  mile,  will  all  have  the  same 
velocity  of  flow,  but  the  volume  of  sewage  in  the  lo-foot  sewer 
must  be  100  times,  in  the  5-foot  sewer  25  times,  and  in  the 
2-foot  sewer  4  times,  the  volume  of  sewage  in  the  i-foot 
sewer. 

To  calculate  the  discharge  from  sewers,  the  following  formula 
is  generally  used : — 

Let  V  =  velocity  of  flow  in  feet  per  minute. 
D  =  hydraulic  mean  depth. 
F=fall  in  feet  per  mile. 
Then  V=5  5  VD^  2F. 

If  A  =  sectional  area  of  current  of  fluid,  Vx  A=  discharge  in 
cubic  feet  per  minute.  The  hydrauhc  mean  depth  is  the  sec- 
tional area  of  the  current  of  fluid  -^  the  wetted  perimeter  [i.e., 
that  part  of  the  circumference  of  the  sewer  wetted  by  the  fluid 
flowing  through  it) ;  in  circular  sewers  running  full  or  half  full 
it  is  one-fourth  the  diameter.  The  term,  when  applied  to  a  sewer, 
implies  the  depth  of  a  rectangular  channel  whose  sectional  area 
equals  that  of  the  curviUnear  channel  under  consideration,  and 
whose  width  is  equal  to  the  entire  wetted  perimeter  of  the  latter. 

In  modern  systems  of  sewerage,  the  sewers  are  laid  in  straight 
lines  with  manholes  at  every  point  of  change  of  direction.     The 


124  HYGIENE    AND   PUBLIC    HEALTH 

inspection  and  cleansing  of  the  sewers  is  much  faciHtated  by 
such  an  arrangement.  The  best  form  of  sewer  in  all  cases  in 
which  the  volume  of  sewage  undergoes  fluctuation  is  the  egg- 
shaped,  the  small  end  of  the  egg  being  downwards.  In  this 
form  there  is  a  greater  depth  of  sewage  and  less  contact  with 
the  walls  of  the  sewer  (and  consequently  less  friction)  than  in 
any  other  form.  For  outfall  sewers,  in  which  the  volume  of 
sewage  to  be  conveyed  is  large  and  uniform,  Mr.  Baldwin  Latham 
advises  the  circular  form,  as  it  is  cheaper  and  stronger  when 
constructed.  Up  to  i8  inches  internal  diameter,  sewers  should 
be  circular  in  section;  and  for  these  small  sizes,  stoneware, 
cement,  or  concrete  pipes  are  better  than  sewers  constructed 
of  brick.  Iron  pipes  and  patent  joints  in  stoneware  pipes  are 
often  used  in  damp  sites.  No  public  sewer  should  be  less  than 
9  inches  in  diameter,  owing  to  the  risk  of  smaller  pipes  becoming 
obstructed  and  stopped  up  by  articles  improperly  introduced 
into  the  house  drains. 

Sewers  of  unequal  sectional  area  should  not  join  with  level 
inverts;  but  the  bottom  of  the  lesser  sewer  should  have  a  fall 
into  the  main  at  least  equal  to  the  difference  between  the 
diameters  of  the  tributary  and  the  main  sewer. 

Well  burnt,  tough,  impervious  bricks,  or  glazed  firebricks, 
should  be  used  in  the  construction  of  sewers,  especially  in  the 
construction  of  the  lowest  segment  or  invert  of  the  sewer,  which 
is  the  part  most  liable  to  wear  and  erosion  from  the  passage  of 
stones  and  grit  in  the  sewage  over  it.  For  the  smaller  sewers 
suitably  curved  bricks  only  should  be  used.  Sewers  under  3  feet 
in  diameter,  when  laid  in  good  ground,  may  be  constructed 
of  4-J-inch  brickwork.  When  laid  in  bad  shifting  ground,  or 
for  larger  sewers,  g-inch  brickwork  should  be  used.  Suitably 
curved  stoneware  blocks  are  sometimes  used  for  the  inverts  of 
sewers;  their  smooth  hard  upper  faces  forming  an  excellent 
floor  for  the  sewer.  When  these  blocks  are  made  hollow,  they 
provide  a  means  of  draining  off  the  subsoil  water  during  the 
construction  of  the  sewer;  but  engineers  do  not  now  advise 
their  use,  as  the  hollow  block  is  apt  to  split  from  the  weight 
of  the  sewer  built  over  it ;  and  in  sandy  soils  sand  in  the 
subsoil  water  passes  into  the  hollow  blocks  and  may  cause 
settlement  of  the  sewer.  The  mortar  used  in  jointing  the 
bricks  should  be  made  of  the  best  Portland  cement  and  fine 
sharp  sand. 


DISPOSAL   OF   REFUSE  I25 

llie  Separate  System. — Where  it  is  intended  to  convey  away 
sewage  proper  only,  storm,  surface,  and  subsoil  waters  being 
separated,  the  sewers  need  be  only  of  small  size.  Under  such 
circumstances  glazed  stoneware  pipes  jointed  with  Portland 
cement,  are  generally  used  to  form  the  tributaries,  whilst  the 
outfall  sewer  is  constructed  of  brickwork.  Cement  or  silicated 
concrete  pipes  have  been  used,  especially  in  Germany,  instead 
of  stoneware  pipes.  They  are  said  to  be  less  brittle,  to  withstand 
extremes  of  climate,  and  to  resist  the  chemical  action  of  the 
sewage  better  than  stoneware  pipes.  Under  the  separate 
system,  the  sewers,  of  whatever  material,  must  receive  water- 
closet  sewage  and  waste  waters  only;  all  rain-water  from  yards, 
or  areas,  must  be  conveyed  by  separate  pipes  into  surface 
channels  at  the  sides  of  the  streets,  when  the  gradients  are 
sufficient,  or  into  underground  channels  constituting  a  system 
of  drains  quite  distinct  from  the  sewers.  At  convenient  points 
the  surface  channels  or  underground  drains  should  discharge 
into  the  stream  or  river  which  forms  the  natural  drainage  bed 
of  the  locahty.  The  drainage  of  the  subsoil  should  be  effected 
by  agricultural  tile  drains  laid  in  the  same  trench,  but  above 
the  sewers,  and  diverted  into  the  watercourses  at  all  suitable 
points. 

The  advantages  of  the  separate  system  are:  (i)  The  volume 
of  sewage  to  be  conveyed  outside  the  town  is  small  as  compared 
with  that  to  be  dealt  with  by  the  combined  system;  its  daily 
or  seasonal  fluctuations,  and  the  total  quantities  to  be  dealt  with, 
can  be  calculated  approximately  from  the  population  and 
water  supply  (points  of  great  importance  where  the  sewage 
has  to  be  pumped  to  the  outfall,  or  to  be  purified  before  being 
discharged) ;  (2)  the  sewage  is  uniform  in  composition  because 
protected  from  dilution  with  storm  waters,  and  its  purification 
and  utilization  day  by  day  are  therefore  undertaken  with  much 
less  difficulty  than  is  the  case  with  sewage  which  is  sometimes 
strong  and  at  others  very  weak  from  admixture  with  rain  and 
subsoil  waters;  (3)  the  sewers,  being  small  and  having  smooth 
walls,  are  more  frequently  flushed,  and  there  is  less  tendency 
to  deposit,  with  formation  of  foul  gases,  than  in  the  case  of  the 
larger  brick  sewers. 

The  disadvantages  are:  (i)  That  every  house  must  have  two 
drains  or  two  sets  of  pipes — one  for  sewage  and  the  other  for 
rain-water ;  and  this  gives  rise  to  mistakes  on  the  part  of  builders. 


126  HYGIENE   AND    PUBLIC   HEALTH 

who  occasionally  connect  the  pipes  with  the  wrong  system; 
(2)  that  the  surface  water  from  yards  and  streets  is  often  too 
foul  to  admit  into  a  stream,  especially  when  a  storm  succeeds 
a  period  of  drought,  unless  the  yards  and  streets  are  constantly 
cleansed  and  well  scavenged;  (3)  that  the  flushing  effect  on  the 
sewers  of  storm  waters  is  lost.  It  is,  however,  sufficiently 
obvious  that  these  disadvantages  in  no  way  counterbalance  the 
undoubted  advantages  of  the  separate  system. 

Inspection,  Flushing,  and  Ventilation  of  Sewers. 

In  any  system  of  sewerage  it  is  necessary  to  provide  means 
of  access  to  the  sewers  for  their  cleansing  and  for  the  removal 
of  accumulations  of  deposit.  Manholes  are  shafts  sunk  from 
the  surface  of  the  road  to  the  sewer  by  which  the  sewer-men 
can  descend.  They  are  constructed  of  brickwork,  and  pro- 
vided with  a  locked  iron  door  at  the  street  level.  In  streets 
where  there  is  much  traffic,  the  shaft  is  sunk  from  the  footway 
perpendicularly  for  a  short  distance,  and  then  carried  down 
by  means  of  steps  to  the  side  of  the  sewer.  In  other  cases  the 
manholes  are  sunk  from  the  middle  of  the  road  to  the  crown  of 
the  sewer.  They  have  also  a  variety  of  other  uses;  they  are 
used  as  points  of  junction  between  tributary  pipe  sewers  and 
the  main  sewer,  curved  channels  being  constructed  in  the  floor 
of  the  manhole;  and  they  are  also  the  points  at  which  flushing 
gates  may  most  advantageously  be  fixed  in  brick  sewers. 

Flushing  gates  are  sluices  made  to  fit  the  whole  or  part  of  the 
sectional  area  of  a  sewer.  When  in  position  they  dam  back  the 
sewage  in  the  sewer  above,  and  on  being  raised,  or  liberated, 
the  sewage  so  stored  rushes  forwards  and  effectually  flushes 
the  sewer  below.  Self-acting  gates  are  often  used  for  this 
purpose.  The  gate  being  hinged  below  its  centre,  the  pressure 
of  the  sewage  on  that  portion  of  the  gate  which  is  below  the 
hinge  fixes  it  in  position.  As  the  sewage  rises,  the  upper  portion 
of  the  gate  is  likewise  exposed  to  the  pressure  of  the  sewage, 
and  presenting  a  larger  area  than  the  part  below  the  hinge,  a 
point  is  at  length  reached  when  the  gate  tilts,  assuming  a  hori- 
zontal position,  and  the  sewage  escapes.  Flushing  gates  are 
not  used  for  flushing  the  upper  ends  of  brick  sewers,  nor  are  they 
used  for  flushing  pipe  sewers.  For  tliese  purposes,  automatically 
discharging  siphon  flush  tanks  find  a  most  useful  application. 
They  should  be  supplied  with  water  from  a  tap  connected  with 


DISPOSAL   OF    REFUSE  127 

the  town  water  mains,  and  regulated  to  discharge  at  intervals 
as  required. 

It  might  be  thought  that  the  pipe  sewers  used  with  the  separate 
system  do  not  require  artificial  flushing.  But  experience  has 
taught  otherwise,  and  it  nmst  be  remembered  also  that  under 
this  system  the  sewers  are  not  flushed  by  storm  waters.  There 
can  be  no  doubt  that  heavy  rainfall  is  very  effectual  in  flushing 
sewers;  but  besides  introducing  a  quantity  of  grit  and  sand 
from  the  roads,  rainfall  cannot  be  depended  upon  in  this  climate 
to  occur  at  properly  recurring  intervals,  and  is  often  absent  for 
long  periods  in  summer,  when  sewer  deposits  are  most  abundant 
and  offensive. 

The  ventilation  of  sewers  is  a  matter  of  importance,  as  the 
health  of  a  sewered  district  probably  depends  to  some  extent 
on  the  efficiency  of  the  sewer  ventilation. 

The  most  offensive  gases  are  given  off  from  sewerd  in  which 
deposit  forms,  such  as  the  old-fashioned  brick  conduits  with 
flat  bottoms,  or  oval  sewers  in  which  a  portion  of  the  invert  has 
sunk  below  its  proper  level,  or  sewers  which  are  too  large  for 
the  volume  of  sewage  they  ordinarily  convey,  and  in  which  the 
deposits  and  slime,  formed  on  their  floors  and  sides,  are  not 
removed  by  flushing.  Outfall  sewers  in  which  sewage  is,  for 
any  reason,  backed  up  and  stagnant  during  a  portion  of  the 
day  are  also  liable  to  become  sewers  of  deposit.  The  deposit 
rapidly  putrefies,  giving  off  offensive  gases,  which  escape  through 
the  nearest  ventilator;  or  should  the  sewer  be  insufliciently 
ventilated,  the  foul  gases  find  an  exit  through  house  drains 
and  traps  into  the  interior  of  houses. 

In  all  sewers,  owing  to  the  constant  variation  of  the  flow 
of  sewage  through  them,  some  deposit  forms  on  their  sides, 
which,  being  alternately  wet  and  dry,  rapidly  putrefies  and 
parts  with  its  putrefactive  ferments  to  the  sewage  flowing  by. 
In  pipe  sewers  there  is  less  tendency  to  deposit  than  in  brick 
sewers  of  large  diameter,  owing  to  the  smooth  internal  surfaces 
of  the  pipes,  and  to  the  greater  frequency  with  which  they  are 
washed,  as  pipe  sewers  are  more  often  running  fuU  or  nearly 
full  than  brick  sewers. 

Natural  ventilation  of  sewers,  by  which  movements  of  air  in 
them  are  produced,  is  due  to  a  variety  of  causes,  the  most 
important  of  which  are : — (i)  Where  there  is  a  strong  and  rapid 
stream,  a  current  of  air  is  produced  which  is  in  the  same  direc- 


128  HYGIENE   AND    PUBLIC   HEALTH 

tion  as  the  sewage  stream,  and  of  proportional  velocity.  Most 
of  the  openings  into  the  sewers  will  be  inlets  for  fresh  air  (drawn 
in  by  the  current  of  air  beneath),  which  finally  escapes  through 
the  outfall  sewer.  (2)  During  the  cold  months  of  the  year 
the  temperature  inside  a  sewer  is,  owing  to  the  warmth  of  the 
sewage,  higher  (average  about  7°  F.)  than  that  of  the  external 
atmosphere,  consequently  the  warmer  sewer  air  tends  to  rise 
and  to  be  replaced  by  the  cold  external  air.  During  the  warm 
months  of  the  year  the  temperature  of  the  sewer  is  by  day  often 
considerably  cooler  than  the  external  air.  In  spring  and  autumn 
the   temperatures   inside   and   outside   are   more   nearly  equal. 

(3)  The  air  of  sewers  is  generally  saturated  with  moisture, 
and  therefore  lighter  as  a  rule  than  the  general  atmosphere 
outside,  both  in  summer  and  winter.  For  this  reason  sewer  air 
generally  tends  to  rise  up  from  any  openings  into  the  sewer. 

(4)  The  passage  of  hot  liquids  from  houses  and  from  factory 
boilers  causes  a  rise  in  the  temperature  of  the  sewage  and  ex- 
pansion of  the  sewer  air.  Blowing  off  steam  from  boilers  into 
sewers  causes  a  great  rise  of  pressure,  and  unless  ample  ventila- 
tion is  provided  house  traps  will  be  forced.  (5)  During  the 
early  part  of  the  day,  the  volume  of  sewage  in  the  sewers  increases 
rapidly  to  a  maximum,  and  air  is  consequently  slowly  expelled, 
to  be  replaced  by  inflowing  air  as  the  level  of  the  sewage  falls. 
The  rising  of  the  tide  in  an  outfall  sewer,  not  protected  by  a 
tidal  valve,  will  also  displace  air,  but  the  displacement  is  so 
gradual  as  to  be  almost  inappreciable.  Where  storm  waters 
are  admitted  into  the  sewers,  sudden  heavy  rainfalls  exert  a 
marked  influence  in  expelling  air,  which  is  somewhat  counter- 
balanced by  the  aspirating  effect  produced  by  the  flow  of  air 
in  the  direction  of  the  current.  (6)  Sudden  falls  of  barometrical 
pressure  cause  air  and  gases  dissolved  in  the  sewage  to  be  given 
off.  (7)  Sudden  variations  in  temperature  of  the  external  air 
produce  variations  in  pressure  of  the  sewer  air.  A  high  tempera- 
ture favours  decomposition  of  the  sewage  and  evolution  of  gases. 

Openings  into  the  crowns  of  sewers  from  the  surface  of  the 
roadway  should  be  made  at  distances  of  not  more  than  100  3'ards 
apart.  Some  of  these  will  act  as  inlets,  and  others  as  outlets, 
and  the  pressure  of  air  in  the  sewer  will  at  no  time  be  able  to 
rise  sufficiently  to  force  the  traps  on  house  pipes  and  drains. 

There  are  objections  which  apply  to  the  method  of  ventilating 
sewers  by  means  of  the  soil  pipe  ventilators  of  houses,  as  when 


DISPOSAL   OF    REFUSE  I29 

this  method  is  carried  out  there  must  be  no  disconnecting  traps 
to  the  house  drains  and  fresh-air  inlets  to  the  drains  cannot 
be  fixed.  Sewer  air  escaping  in  large  volumes  near  dormer 
windows  might  also  cause  a  serious  nuisance.  Where  a  dis- 
connecting trap  is  fixed  on  the  house  drain,  a  4-inch  pipe  may 
be  carried  up  to  the  ridge  of  the  roof  from  the  drain  on  the 
sewer  side  of  the  trap,  its  end  being  left  open;  and  it  will  be 
found  useful  as  an  exit  for  sewer  air  when  used  in  combination 
with  road  ventilators.  But  it  is  needful  to  bear  in  mind  that 
where  rain-water  is  admitted  to  the  sewers,  during  heavy  rainfall 
when  ventilation  is  most  required  for  affording  a  safe  exit  for 
suddenly  displaced  sewer  air,  house  drains,  or  any  part  of 
them,  are  often  useless  for  this  purpose,  as  their  openings  into 
the  sewer  may  be  sealed  by  the  height  at  which  the  sewage 
is  flowing  in  the  sewer. 

The  best  form  of  street  ventilator  is  the  shaft  sunk  from  the 
middle  of  the  roadway  to  the  crown  of  the  sewer.  Beneath  the 
grating  at  the  surface  of  the  street  should  be  placed  a  dirt  box 
to  catch  gravel  and  mud,  which  would  otherwise  fall  into  the 
sewer,  a  space  being  left  around  the  box  for  the  passage  of  air. 
The  dirt  box  should  be  capable  of  removal  from  the  surface  of 
the  road.  Ventilators  may  also  be  constructed  in  connection 
with  manholes.  A  shaft  is  sunk  for  a  short  distance  by  the 
side  of  the  manhole,  openings  being  made  between  them  for 
the  passage  of  air.  Mud  and  gravel  fall  to  the  bottom  of  this 
shaft,  from  which  a  pipe  conducts  the  water  to  the  sewer  beneath. 
The  air  which  escapes  from  the  sewers  by  these  street  ventilators 
is  rapidly  diluted  with  fresh  air;  and,  from  their  position  in 
the  centre  of  the  roadway,  there  is  the  least  chance  of  offence  to 
foot  passengers  or  of  foul  air  gaining  entrance  to  houses.  In 
narrow  courts  and  streets,  especially  at  the  upper  or  dead  ends 
of  sewers,  the  surface  ventilators  should  be  replaced  by  shafts 
carried  up  from  the  crown  of  the  sewer  to  above  the  tops  of 
houses;  for  it  is  desirable  to  avoid  any  risk  of  foul  sewer  air 
collecting  in  stagnant  courts  and  streets  surrounded  by  buildings, 
in  which  rapid  dilution  of  the  sewer  exhalations  with  fresh  air 
might  not  always  take  place.  Street  gulleys  should  be  effectually 
trapped,  both  to  prevent  mud  and  sand  entering  the  sewer, 
and  to  avoid  an  escape  of  sewer  air  close  to  the  footways  and 
the  fronts  of  houses. 

Iron  wire  baskets  containing  small  wood  charcoal  were   at 

9 


130  HYGIENE    AND   PUBLIC   HEALTH 

one  time  extensively  used  to  sweeten  the  air  escaping  through 
the  ventilators.  When  dry  they  exercise  considerable  influence 
in  oxidizing  and  deodorizing  organic  vapours.  But  they  rapidly 
become  wet  from  rain  and  watery  vapour,  and  then  they  are 
not  only  useless  as  deodorizers,  but  the  pores  are  so  clogged  as 
to  obstruct  all  passage  of  air  through  them.  For  these  reasons 
their  use  has  been  nearly  everywhere  discontinued. 

Various  processes  (such  as  Reeves')  have  from  time  to  time 
been  patented  for  deodorizing  the  sewer  air  escaping  from  street 
ventilators  by  bringing  it  in  contact  with  gases,  generated  by 
the  automatic  and  gradual  mixing  of  different  chemical  solu- 
tions. More  recently  a  method  of  cremating  the  sewer  air,  by 
passing  it  over  or  through  a  gas  flame  placed  in  a  chamber  at 
the  top  of  the  ventilator,  has  been  tried.  By  this  method  the 
escaping  sewer  air  is  heated,  possibly  even  to  the  point  of  steriliza- 
tion, whilst  the  combustion  of  the  gas  tends  to  create  an  artificial 
draught  up  the  sewer  ventilator.  There  can  be  no  question 
that  any  general  adoption  of  such  systems  is  undesirable.  If 
the  sewers  are  well  laid  and  self-cleansing,  they  are  not  required. 
Should  the  sewers  be  so  old  and  dilapidated  as  to  be  generally 
offensive  throughout  a  district,  it  would  prove  more  satisfactory 
and  far  more  beneficial  to  the  public  health,  to  reconstruct  them 
on  modern  principles  than  to  inaugurate  a  system  of  concealing 
the  effects  without  attacking  the  cause. 

Where  sewers  are  laid  with  steep  gradients,  it  is  found  that 
the  current  of  air  tends  to  pass  in  the  reverse  direction  to  the 
flow  of  the  sewage  from  the  low  to  the  high  levels.  To  prevent 
the  escape  of  large  volumes  of  foul  air  at  the  upper  parts  of  a 
sewered  district,  it  is  therefore  necessary  to  construct  at  various 
points  a  tumbling  bay — ^with  manhole  and  ventilator  opening 
above  at  the  street  level.  Then  the  sewer  air  in  its  course 
upwards  meet  a  flap  valve,  hung  from  the  crown  of  the  sewer 
immediately  over  the  tumbling  bay,  and  is  forced  to  escape 
into  the  outer  air  through  the  ventilator. 

It  was  at  one  time  thought  that  by  connecting  sewers,  by 
means  of  shafts,  with  a  furnace  chimney,  a  powerful  extractive 
force,  useful  in  ventilating  a  large  portion  of  the  system,  would 
be  put  in  operation.  By  this  method,  however,  a  great  draught 
for  a  short  distance  only  is  produced,  as  air  rushes  in  from  all 
openings  in  the  neighbourhood  to  supply  the  place  of  that 
extracted  by  the  furnace.    Beyond  a  very  short  distance  no 


DISPOSAL   OF   REFUSE  I3I 

effect  is  prodaccd,  and  there  is  besides  considerable  risk  of  traps 
in  houses  being  drawn.  If  any  such  method  is  adopted,  the 
chimney  selected  should  be  one  in  connection  with  a  furnace 
which  is  kept  going  day  and  night  throughout  the  entire  year, 
and  all  untrapped  openings  into  the  sewers  in  the  neighbourhood 
of  the  furnace  must  be  carefully  closed.  At  the  same  time  the 
connections  of  house  drains  to  the  sewers  should  be  examined,  to 
make  certain  that  such  an  intercepting  siphon  trap  exists  on 
every  drain  as  will  not  become  unsealed.  The  method  is  really 
only  applicable  to  large  main  sewers  which  do  not  receive  house 
drains,  but  intercept  the  sewage  from  tributary  sewers. 

Outfall  Servers. — In  some  cases  it  may  be  necessary  to  carry 
the  sewage  of  a  town  across  a  river  or  a  valley.  This  may 
sometimes  be  done  by  bridging;  but  usually  the  outfall  sewer 
is  at  too  low  a  level  to  permit  of  it.  In  such  cases  the  sewer 
should  be  carried  across  by  means  of  an  inverted  siphon,  formed 
of  wrought-iron  pipes  with  riveted  flange  joints,  laid  in  the  bed 
of  the  river  or  valley.  Arrangements  must  be  made  for  pre- 
venting the  accumulation  of  solid  matters  at  the  lowest  point 
of  the  siphon,  resulting  eventually  in  a  stoppage,  to  which  there 
is  a  tendency  unless  the  current  through  is  of  sufficient  velocity 
to  carry  all  solid  matters  with  it.  With  this  view  the  sewage 
may  be  strained  before  passing  through  the  siphon,  or  the  siphon 
must  be  periodically  flushed.  To  give  exit  to  air  under  pressure 
in  the  siphon,  which  might  prevent  its  proper  action,  a  ventilating 
pipe  should  be  attached  to  the  descending  arm. 

The  Disposal  of  Sewage. 

The  disposal  of  the  sewage  of  a  town  or  district  is  often  a 
most  difficult  problem  to  solve.  Since  the  Rivers  Pollution 
Prevention  Act  became  law  in  1876,  it  has  been  illegal  to  discharge 
crude  sewage  into  a  stream — this  term  including  rivers,  streams, 
canals,  lakes,  and  watercourses,  other  than  watercourses  mainly 
used  as  sewers,  and  also  the  sea  to  such  extent,  and  tidal  waters 
to  such  point,  as  may  after  local  inquiry,  or  on  sanitary  grounds, 
be  determined  by  the  Local  Government  Board.  It  is  greatly 
to  be  regretted  that  this  Act  has  in  many  parts  of  the  country 
entirely  failed  to  prevent  the  continued  pollution  of  streams, 
from  which  the  community  has  already  so  largely  suffered. 

Where  sewage  is  discharged  into  fresh  nmning  water  and  at 
once  largely  diluted,  it  becomes  in  course  of  time  to  a  great 


132  HYGIENE    AND    PUBLIC   HEALTH 

extent  purified.  Distributed  through  a  large  volume  of  river 
water,  the  organic  matters  are  oxidized  (through  the  aid  of  nitri- 
fying bacteria)  by  the  oxygen  dissolved  in  the  water  and  by  that 
given  out  by  minute  water  plants  (algae,  diatoms,  and  desmids), 
and  are  also  assimilated  by  minute  animals  (infusoria,  rhizopoda, 
entomostraca,  anguillulae,  etc.).  They  are  thus  purified,  or  got 
rid  of,  without  the  occurrence  of  putrefaction  and  the  formation 
of  offensive  gases,  which  must  occur  when  the  sewage  is  not 
sufficiently  diluted  with  fresh  water  and  the  temperature  of 
the  air  and  water  is  high — ^the  growth  of  fermentative  bacterial 
organisms  then  taking  place  to  such  an  extent  as  to  cause  putre- 
faction. Putrefactive  bacteria  will  no  doubt  in  time  break  up 
complex  organic  matters  into  their  constituent  parts,  and  thus 
purify  sewage;  but  the  process  is  one  productive  of  nuisance 
and  injury  until  the  ultimate  effect  is  attained. 

In  the  case  of  tidal  sewage-polluted  rivers,  the  Reports  of  the 
Royal  Commission  on  Metropolitan  Sewage  Discharge  show 
that  the  only  true  sources  of  dilution  of  the  sewage  are  the  land 
water  entering  from  above,  and  the  sea  water  from  the  mouth 
of  the  river.  During  dry  weather,  when  the  quantity  of  land 
water  is  slight,  the  displacement  of  the  sewage  towards  the  sea 
is  very  slow  (about  a  quarter  of  a  mile  daily  in  the  case  of  the 
Metropolitan  sewage) ;  so  that  the  sewage  discharged  on  any 
particular  day  oscillates  up  and  down  the  river  with  the  tide, 
and  is  continually  receiving  fresh  increments.  The  sewage,  too, 
that  is  discharged  after  high  water  on  an  ebbing  tide  will  be 
carried  up  by  the  flowing  tide  above  the  outfall ;  and  when  neap 
tides  are  giving  place  to  spring  tides,  the  whole  volume  of  dis- 
charged sewage  is  carried  up  higher  and  higher  above  the  outfalls 
every  day  as  the  spring  tides  increase.  The  consequence  is 
that  at  such  times  the  sewage  may  be  carried  in  the  river  up  to 
or  above  the  town  so  discharging  its  sewage. 

The  effect,  too,  of  the  sea  salts  m  estuary  water  is  to  cause  a 
precipitation  of  organic  matters  and  a  deposit  of  mud,  whilst 
the  oxidation  and  purification  processes  are  delayed  by  their 
presence. 

If  the  volume  of  sewage  discharged  is  relatively  small  to  the 
volume  of  water  in  the  river,  the  sewage  will  in  time  be  purified; 
but  such  water  can  under  no  circumstances  be  a  proper  source 
of  supply  for  drinking  water. 

Under  certain  circumstances  crude  sewage  may  be  discharged 


DISPOSAL   OF   REFUSE  I33 

directly  into  tliu  sea  without  risk  of  nuisance  and  oifcnce.  If 
the  sewage  can  at  all  times  be  borne  away  from  the  shore  out 
to  sea,  it  becomes  mixed  with  an  immense  volume  of  water 
and  rendered  harmless.  The  danger  is  that  sewage  may  be 
cast  up  by  the  tide  on  the  foreshore,  or  borne  along  by  currents 
the  whole  length  of  the  sea  front  of  a  town.  To  avoid  such  an 
event,  the  outfall  must  be  chosen  at  such  a  spot  that  the  sewage, 
at  whatever  state  of  the  tide  it  may  be  discharged,  shall  be 
carried  by  currents,  where  such  exist,  straight  out  to  sea,  or  at 
least  in  a  direction  away  from  the  town.  The  direction  of  the 
currents  may  be  ascertained  by  means  of  float  experiments. 

The  outfall  sewer  must  open  below  the  level  of  the  water  at 
all  states  of  the  tide,  and  its  mouth  should  be  protected  by  a 
tidal  valve  to  prevent  sea  water  entering  it.  The  prevailing 
winds  should  also  be  studied,  to  prevent  the  possibility  of  floating 
faecal  matters  being  blown  back  on  to  the  beach.  If  the  town 
lies  at  a  low  level,  so  that  its  sewers  are  tide  locked  for  several 
hours  of  each  tide,  tanks  must  be  constructed  to  retain  the  sewage 
which  accmnulates  at  such  periods;  or  a  certain  length  of  large 
oval  tank  sewer  must  be  built  to  serve  the  same  purpose. 

Tank  sewers,  however,  are  very  generally  productive  of 
nuisance.  The  tide-locked  sewage  stagnates  in  them,  and  a 
copious  deposit  of  sediment  takes  place  which  gives  rise  to  the 
formation  of  foul  gases.  In  such  cases  no  amount  of  ventilation 
suffices  to  obviate  the  nuisance.  It  is  better  to  have  recourse 
to  steam  pumping  at  the  outfall,  or  to  use  Shone's  Pneumatic 
Sewage  Ejectors  to  relieve  the  sewers  of  their  accumulated 
sewage. 

Shone's  system  is  now  in  operation  at  several  towns  lying  on 
low  flat  ground,  and  has  been  found  very  beneficial  in  preventing 
the  evils  which  result  from  absence  of  proper  sewer  gradients. 

The  motive  power  is  compressed  air,  which  is  conveyed  from 
a  central  station  by  wrought-iron  pipes  to  the  cylindrical  reser- 
voirs or  "  ejectors,"  which  are  situated  in  chambers  beneath  the 
streets  at  different  parts  of  the  town,  and  receive  the  sewage 
from  the  street  sewers.  When  the  ejectors  are  full,  a  valve 
opens  and  compressed  air  is  admitted  by  means  of  a  float  acting 
on  a  counterpoise  lever,  and  the  sewage  is  thereby  forced  out 
into  a  gravitating  sewer  at  a  higher  level.  A  ball  valve  in  the 
pipe  sewer  entering  the  "  ejector  "  prevents  the  sewage  from  being 
forced  backwards  by  the  compressed  air;  and  as  the  sewage  is 


134  HYGIENE    AND    PUBLIC  HEALTH 

discharged  and  its  level  sinks  in  the  "  ejector,"  the  sinking  of  the 
float  closes  the  valve  of  the  compressed  air  tube,  and  a  fresh 
charge  of  sewage  can  then  enter.  The  great  advantage  of  the 
system  is  that  good  gradients  can  be  given  to  the  sewers,  for  the 
ejectors  are  placed  at  sufficient  depths  below  the  surface  of  the 
ground  to  permit  of  house  drains  and  street  sewers,  with  which 
they  are  connected,  having  a  good  fall;  and  the  sewage  can 
thus  be  carried  away  and  forced  out  of  the  town  in  a  fresh  con- 
dition. In  addition,  no  storage  is  required  as  in  ordinary  pump- 
ing, for  the  rate  of  working  of  the  ejectors  varies  with  the  rate 
of  flow  of  the  sewage  into  them,  although  the  air  compression 
machinery  at  the  central  station  works  nearly  uniformly. 

Liernur's  pneumatic  system  of  sewage  removal  and  treat- 
ment is  carried  out  at  Amsterdam  and  Trouville.  It  is  claimed 
to  be  especially  applicable  in  towns  where  the  water  supply  is 
limited,  and  where  the  ground  is  too  flat  to  admit  of  good  sewer 
gradients.  There  is  an  air-tight  system  of  sewers,  the  contents 
of  which  are  drawn  into  closed  chambers  fixed  in  different  parts 
of  the  town,  by  means  of  a  powerful  air  pump  at  a  central  station. 
From  these  chambers  the  sewage  is  sucked  into  a  steam  concen- 
trator at  the  central  station,  and  is  there  heated  to  about  ioo°  C, 
after  the  ammonia  has  been  fixed  by  the  addition  of  sulphuric 
acid.  The  dried  sludge  ("  poudrette  ")  finds  a  ready  market  as 
manure.  It  appears  that  the  pipes  tend  to  get  clogged,  but 
otherwise  the  system  works  well. 

The  Purification  and  Utilization  of  Sewage. 

It  can  safely  be  said  that  in  this  country  no  stream  or  river 
should  ever  receive  crude  sewage;  for  so  numerous  are  the 
towns  on  the  banks  of  nearly  every  stream,  that,  although  the 
sewage  of  one  town  might  be  purified  after  a  certain  run,  it  would 
be  quite  impossible  for  any  stream  to  purify  the  successive 
sewage  discharges  from  every  town  on  its  banks.  As  the  sewage 
must  be  purified  before  discharge,  the  question  arises  whether 
the  manurial  matters  contained  in  it  can  be  utilized,  and  made 
to  pay  the  whole  or  part  of  the  expenses  incurred  in  its  purifica- 
tion. It  becomes  necessary,  then,  to  consider  the  amount  and 
value  of  the  manurial  ingredients  contained  in  ordinary  town 
sewage. 

In  the  first  place  as  to  the  chemical  composition  of  sewage. 
The  Rivers  Pollution  Commissioners  give  as  the  average  in  water- 


DISPOSAL  OF   REFXTSE  135 

closeted  towns,  in  100,000  parts,  722  of  total  solid  matters  in 
solution,  in  which  there  are  6703  of  ammonia;  total  combined 
nitrogen,  7728;  chlorine,  1066;  and  an  inappreciable  quantity 
of  nitrogen  as  nitrates  and  nitrites.  In  100,000  parts  there  are, 
besides,  44  69  of  suspended  matters,  of  which  2051  are  organic, 
and  24- 18  mineral  matters.  This  is  an  average  from  a  large 
number  of  analyses ;  but  it  must  be  borne  in  mind  that  the  sewage 
of  different  towns  varies  greatly  in  character,  and  that  the  sewage 
of  the  same  town  varies  in  strength  from  day  to  day  and  from 
hour  to  hour.  To  obtain  an  exact  knowledge  of  the  average 
strength  of  a  day's  sewage  in  any  town,  samples  must  be  taken 
frequently — at  least  every  hour — and  to  form  a  sample  for 
analysis  they  must  be  mixed  in  such  proportions  as  are  indicated 
by  gauging  the  flow  of  sewage  at  the  time  each  sample  was  taken. 
In  this  way  only  can  the  average  composition  of  the  sewage  be 
arrived  at  with  anything  Hke  exactitude. 

The  strength  of  the  sewage  depends  on  the  number  of  water- 
closets  in  the  town  (proportion  of  water-closets  to  middens), 
the  amount  of  water  supply  per  head  of  the  population,  the 
amount  of  waste  liquors  discharged  into  the  sewers  from  manu- 
factories, and,  in  the  case  of  combined  sewers,  the  amount  of 
rain  that  has  fallen  and  of  subsoil  water  that  has  found  its  way 
into  them.  During  the  early  part  of  the  day  (in  dry  weather) 
the  sewage  of  any  town  is  strongest  and  the  flow  greatest,  whilst 
at  night  the  sewers  may  be  discharging  nothing  but  subsoil 
water. 

The  chief  valuable  ingredients  of  sewage  are  the  different  forms 
of  combined  nitrogen,  the  phosphates,  and  salts  of  potash.  The 
money  value  of  these  constituents  in  100  tons  of  the  sewage  of 
the  strength  noted  above  is  17s.,  the  dissolved  matters  being 
worth  15s.,  the  suspended  2s.  This  gives  a  value  to  the  sewage 
of  about  2d.  per  ton.  We  have  already  seen  that  the  yearly 
excretal  refuse  of  an  individual  of  a  mixed  population  is  worth 
from  6s.  8^.  to  7s.  [see  p.  76),  and  this  refuse,  if  diluted  with  water 
to  form  40  tons  of  sewage  (an  average  dilution  of  24  gallons  per 
head  per  day),  will  also  give  a  value  to  the  sewage  of  2d.  per 
ton.  This  dilution  is  about  that  of  the  London  sewage  during 
dry  weather.  It  may  further  be  stated  that  855  tons  of  the 
sewage  of  the  composition  given  by  the  Rivers  Pollution  Com- 
missioners contain  i  ton  of  solid  matters  (in  solution  and  in 
suspension),  estimated  to  be  worth  £7  5s.  4^.     From  such  data 


136  HYGIENE  AND  PUBLIC  HEALTH 

as  these  calculations  might  be  made  of  the  total  yearly  value 
of  the  sewage  of  any  town.  But  such  theoretical  calculations 
are  very  far  from  representing  the  real  values  available  for 
agricultural  purposes. 

The  composition  of  sewage  from  midden  towns  {sec  p.  yy) 
does  not  differ  very  materially  from  that  of  water-closeted  towns. 
The  Rivers  Pollution  Commissioners  gave  as  the  average  com- 
position of  midden  town  sewage  in  100,000  parts:  Total  solids  in 
solution,  824;  organic  nitrogen,  1975;  ammonia,  5435;  total 
combined  nitrogen,  6-451;  total  solids  in  suspension,  3911,  of 
which  21-30  are  organic  matters,  and  17-81  mineral  matters. 

Subsidence,  Straining,  and  Precipitation. 

By  allowing  sewage  to  settle  in  tanks,  a  portion  of  the  sus- 
pended matters  subsides  to  the  bottom  and  a  more  or  less 
clarified  liquid  can  be  decanted  from  the  top.  By  straining 
crude  sewage  through  beds  of  ashes  or  charcoal,  the  suspended 
matters  are  removed;  but  the  filters  speedily  become  clogged, 
and  require  frequent  renewal  at  great  expense. 

Certain  chemical  substances,  when  mixed  with  sewage,  cause 
a  more  rapid  and  copious  precii^itation  of  the  suspended  matters 
than  can  be  effected  by  subsidence  alone.  The  number  of 
chemicals  that  have  been  used  or  advocated  for  this  purpose  is 
enormous,  as  may  be  seen  on  inspection  of  the  specifications  of 
patents  taken  out  to  protect  the  inventors  of  such  processes. 
Lime — as  lime  water  or  milk  of  lime — sulphate  of  alumina,  and 
protosulphate  of  iron,  are  the  substances  now  most  commonty 
used  as  precipitation  agents.  Lime  is  the  most  frequently 
employed — either  alone  or  in  combination  with  sulphate  of 
alumina  or  iron. 

The  precipitating  effect  of  lime  on  sewage  is  due  partly  to  its 
combination  with  carbonic  acid,  forming  an  insoluble  carbonate 
of  hme,  and  partly  to  its  combination  with  some  of  the  organic 
bases  of  sewage.  These  substances  subside,  carrying  with  them 
most  of  the  suspended  matters  in  the  sewage,  and  sink  to  the 
bottom  of  the  tank,  forming  the  sludge;  whilst  a  more  or  less 
clear  liquid  remains  above.  If  too  much  lime  is  added,  the 
sludge  and  supernatant  liquid,  being  strongly  alkaline,  tend 
soon  to  undergo  decomposition.  The  proportion  of  lime  usually 
added  to  sewage  of  average  strength  is  about  12  grains  to  the 
gallon  of  sewage. 


DISPOSAL   OF   REFUSE  I37 

The  precipitating  effect  of  sulphate  of  alumina  on  sewage  is 
due  to  combination  of  the  sulphuric  acid  with  lime  and  other 
bases  in  the  sewage,  whilst  the  alumina  hydrate  is  precipitated 
in  a  flocculent  condition,  entangling  and  carrying  down  in  its 
course  most  of  the  suspended  organic  matters.  The  crude 
sulphate  of  alumina  used  as  a  precipitant  is  acid,  and  reduces 
somewhat  the  alkalinity  of  the  lime  when  this  material  is  em- 
ployed in  combination  with  it.  For  treating  sewage  of  medium 
strength  the  quantities  need  not  exceed  5  grains  of  hme  and 
5  grains  of  sulphate  of  alumina  per  gallon  of  sewage. 

When  protosulphate  of  iron  is  added  to  alkaline  sewage  or  to 
sewage  which  has  been  already  treated  with  lime,  a  highly  floc- 
culent hydrated  protoxide  of  iron  is  formed,  which  falls  to  the 
bottom  of  the  tank,  carrying  suspended  organic  matters  with  it. 
The  iron  salt  is  also  a  powerful  antiseptic,  checking  further  putre- 
faction of  the  sludge  and  effluent,  when  used  in  sufficient  quantity. 
But  its  use  is  attended  with  the  disadvantage  that  the  mud 
banks  of  the  stream,  into  which  the  efHuent  is  discharged,  are 
blackened  by  the  formation  of  sulphide  of  iron.  When  used  with 
hme,  protosulphate  of  iron  should  be  added  in  the  proportion  of 
from  2  to  5  grains  per  gallon  of  average  sewage.  Tlie  London 
sewage  is  thus  treated,  the  lime  and  iron  being  added  in  the 
proportion  of  5  and  2  grains,  respectively,  to  the  gallon  of 
sewage. 

The  combination  of  iron  with  alumina  is  also  effective  as  a 
precipitating  agent,  and  both  enter  into  the  composition  of  two 
well-known  sewage  precipitants — Ferrozone  and  Aluminoferric. 

These  three  precipitating  agents — lime,  sulphate  of  alumina, 
and  protosulphate  of  iron — cause  a  more  or  less  complete  deposi- 
tion of  the  suspended  matters  in  sewage,  and  also  remove  the 
grosser  sewage  odour  from  the  effluent;  but  they  have  very 
little  effect  in  removing  from  the  sewage  the  organic  matters 
in  solution.  Sulphate  of  alumina  is  said  to  have  the  effect  of 
removing  5  per  cent,  of  the  dissolved  organic  matters  of  sewage, 
but  lime  and  iron  remove  practically  none.  The  matters  pre- 
cipitated from  sewage,  which  form  the  sludge  at  the  bottom  of  the 
tanks,  are  comparatively  worthless,  whilst  the  bulk  of  the 
valuable  manurial  ingredients  remains  in  the  effluent. 

To  insure  the  most  complete  clarification  of  the  sewage  liquid 
by  chemical  precipitants,  the  following  conditions  must  be 
satisfied:    The  sewage  must  be  fresh  and  undecomposed,  and 


138  HYGIENE   AND   PUBLIC   HEALTH 

the  larger  solid  bodies  should  be  strained  from  it  before  the 
admixture  of  the  chemical  precipitants.  The  chemicals  must  be 
added  to  the  sewage  immediately  before  it  arrives  at  the  tanks, 
and  must  be  well  stirred  and  mixed  up  with  it  by  means  of  rota- 
tory mixers.  There  must  be  sufficient  tank  accommodation. 
The  Local  Government  Board  requires  that  the  tanks  must  be 
capable  of  holding  the  dry  weather  flow  for  24  hours.  The  tanks 
are  often  arranged  in  series,  so  that  the  sewage  may  pass  slowly 
but  continuously  through  two,  three,  or  four  tanks  before  the 
supernatant  liquid  escapes  into  the  effluent  channel,  which  should 
be  kept  scrupulously  clean.  The  tanks  must  be  at  least  4  feet 
deep,  and  the  effluent  passing  out  of  a  tank  should  flow  over  a 
weir  not  more  than  |  inch  below  the  surface  into  the  next  tank 
of  the  series,  or  into  the  effluent  channel.  After  a  certain  period 
of  continuous  working,  the  flow  of  sewage  through  the  series 
must  be  discontinued,  and  the  sludge  allowed  to  settle,  the  clear 
liquid  above  being  drawn  off  through  float  valves  into  the 
effluent  channel.  Sometimes  the  chemically  treated  sewage  is  not 
allowed  to  pass  slowly  from  tank  to  tank  in  series,  but  each  tank 
is  filled  separately.  When  full  the  flow  is  stopped  and  the 
sewage  is  kept  at  rest  for  from  2  to  4  hours  (according  to  its 
strength)  so  that  it  may  deposit  its  sludge.  The  clarified  super- 
natant liquid  is  then  drawn  off.  There  should  be  a  double  set 
of  tanks,  in  order  that  the  treatment  of  the  sewage  may  continue 
whilst  the  sludge  is  being  removed.  The  sludge  must  be  frequently 
removed  or  it  will  putrefy,  and  black  masses  will  be  disengaged, 
which,  rising  to  the  surface,  give  off  foul  gases.  The  tanks, 
when  emptied,  must  be  thoroughly  cleansed  before  being  refilled. 
A  form  of  precipitation  tank  (such  as  the  Dortmund  tank)  with  a 
conical  bottom  has  the  advantage  over  the  old-fashioned  flat- 
bottomed  tank  in  so  far  that  it  permits  the  sludge,  which  falls 
to  the  apex  of  the  cone,  to  be  removed  without  first  drawing 
off  the  supernatant  eifluent. 

Occasionally  substances  which  act  as  deodorants  or  antiseptics 
are  added  to  the  sewage  as  well  as  the  chemical  precipitants. 
The  addition  of  manganate  of  soda  and  sulphuric  acid  to  chemi- 
cally treated  sewage  has  been  recommended  by  Mr.  Dibdin  in 
order  to  promote  oxidation.  Another  deodorizing  method  is 
that  known  as  the  Amines  process.  The  sewage  is  treated  with 
milk  of  lime  and  with  a  small  quantity  of  herring  brine,  which 
contains  a  certain  percentage  of  the  compound  ammonia  termed 


DISPOSAL   OF   REFUSE  I3g 

methylamine.  This  substance  acts  as  a  deodorant  and  antiseptic, 
so  that  the  effluent  undergoes  no  secondary  fermentation; 
whilst  the  sludge  is  so  far  deodorized  that  it  can  be  dried  in 
pits  exposed  to  the  air,  or  on  the  floor  of  a  drying  kiln,  without 
giving  rise  to  noxious  effluvia.  It  is  now  generally  recognized 
that  the  use  of  deodorants,  as  auxiliaries  to  precipitation  pro- 
cesses, is  advantageous  if  they  do  not  interfere  with  the  natural 
agencies  of  purification. 

In  the  Hermite  system  sewage  is  treated  with  partially 
electrolyzed  sea  water.  The  electric  current,  generated  by  a 
dynamo,  is  passed  through  sea  water  contained  in  a  galvanized 
iron  tank,  between  electrodes  of  zinc  and  platinum.  In  doing 
so,  magnesium  chloride  is  probably  decomposed,  forming  a 
disinfecting  fluid  of  a  strength  equal  to  075  gram  of  chlorine 
per  litre.  The  active  principle  of  the  fluid  may  be  an  oxygenated 
compound  of  chlorine,  hypochlorous  acid,  or  hypochlorite  of 
magnesia.  The  solution  has  the  smell  of  a  weak  solution  of 
bleaching  powder.  It  contains  no  free  chlorine.  It  is  claimed 
for  the  process  by  its  inventor  that  the  solution  produces  an 
instantaneous  decomposition  of  faecal  matter  in  sewage,  and 
effectually  sterilizes  the  sewage,  but  the  experiments  conducted 
at  Worthing  do  not  bear  out  these  assertions.  A  solution  of 
bleaching  powder  in  water  would  probabl}^  be  equally  effectual, 
and  much  cheaper. 

In  the  oxychloride  process  sea  water  or  water  containing  10  per 
cent,  of  common  salt  is  electrically  decomposed  in  an  electrolyzer 
having  a  large  superficial  area  of  electrical  surface,  which  permits 
the  use  of  a  high  density  current  at  a  low  voltage.  The  resulting 
liquid  contains  0*2  per  cent,  of  available  chlorine.  From  Dr. 
Rideal's  experiments  at  the  Guildford  Sewage  Works  it  appears 
that  when  mixed  with  appropriate  volumes  of  sewage  effluents 
the  oxychloride  solution  very  largely  reduces  the  total  number 
of  organisms  present  in  the  effluent,  and  practically  eliminates 
Bacillus  coli  communis.  Thus  3^  gallons  of  oxychloride  per 
1,000  gallons  of  secondary  effluent,  i.e.,  effluent  from  septic 
tank  treatment,  contact  beds,  and  streaming  filters,  is  sufflcient 
after  one  hour's  treatment  to  reduce  the  Bacillus  coli  from 
100,000  per  c.c.  of  untreated  effluent,  so  that  none  could  be 
found  in  i  c.c.  It  is  claimed  for  this  process  that  whilst  a  sewage 
effluent  cannot  be  actually  sterilized  by  its  means,  yet  organisms 
of  intestinal  origin  can  be  so  far  ehminated  as  to  render  the 


140  HYGIENE   AND   PUBLIC   HEALTH 

effluent  admissible  into  a  stream  supplying  potable  water,  or 
into  waters  containing  oyster  layings  or  water-cress  beds. 
Oxychloride  solution  itself  is  non-poisonous. 

In  the  ABC  process,  alum,  blood,  clay,  and  animal  and 
vegetable  charcoal  are  added  to  the  sewage.  The  blood  is  said 
to  act  as  a  refiner,  but  in  the  small  quantity  used  its  action  is 
probably  nil;  the  clay  acts  as  a  weighting  material,  carrying 
down  the  precipitated  matters;  whilst  the  charcoal  acts  to  a 
certain  extent  as  a  deodorant.  A  highly  clarified  effluent  is 
produced  by  this  process  on  a  small  area  of  ground,  and  the 
dried  sludge  ("  poudrette  "  or  "  native  guano  ")  can  be  sold  as 
manure. 

The  suspended  matters,  or  sludge,  of  sewage  being  deposited 
at  the  bottom  of  the  settling  tanks,  the  questions  arise:  What 
is  to  be  done  with  the  clarified  sewage  ?  and.  How  is  the  sludge 
to  be  got  rid  of  ?  No  nuisance  will  result  if  the  effluent  is  dis- 
charged into  a  quickly  running  stream  or  river,  whose  volume 
is  at  least  ten  times  greater  than  that  of  the  effluent,  and  which 
is  not  used  below  the  point  of  discharge  as  a  source  of  supply 
of  drinking  water.  The  danger  is  that  during  drought  in  summer 
the  volume  of  fresh  water  might  considerably  diminish;  and 
then,  the  efiiuent  sewage  not  being  sufficiently  diluted,  would 
putrefy  and  become  turbid,  forming  foul  deposits  in  the  bed 
of  the  stream,  and  giving  rise  to  offensive  exhalations.  This 
would  be  especially  likely  to  happen  if,  at  the  same  time,  the 
temperature  of  the  air  was  high.  By  this  method,  too,  all 
the  valuable  manurial  ingredients  of  sewage  run  to  waste.  The 
only  satisfactory  mode  of  purifying  the  effluent  sewage  is  to 
carry  it  over  land  by  irrigation,  or  through  specially  constructed 
filter-beds. 

Where  it  is  not  possible  to  obtain  suitable  land  for  this  pur- 
pose, the  partial  purification  of  the  effluent  from  the  tanks  may 
be  effected  by  passing  through  specially  constnicted  filters, 
consisting  of  burnt  ballast,  coke,  coke- breeze,  coal,  or  gravel ;  or 
the  filters  may  be  composed  of  coarse  sand  laid  upon  magnetic 
oxide  and  carbide  of  iron  (polarite).  The  nitrifying  organisms 
in  the  pores  of  the  filter  exert  a  powerful  oxidizing  effect  on  the 
organic  matters  dissolved  in  the  effluent,  by  which  these  are 
converted  into  nitrates  and  nitrites,  etc.  The  slower  the  filtra- 
tion, i.e.,  the  longer  the  effluent  hquid  is  in  contact  with  the 
particles  composing  the  filter-bed,  the  greater  is  the  purification. 


DISPOSAL   OF   REFUSE  I4I 

The  filtration  must  be  intermittent  to  allow  of  aeration  of  the 
filter. 

The  sludge  left  at  the  bottom  of  the  tanks  is  generally  con- 
ducted into  a  well,  and  thence  pumped  out  in  a  semi-liquid 
condition.  It  then  contains  from  90  to  95  per  cent,  of  water. 
It  may  be  got  rid  of  by  allowing  it  to  flow,  or  by  forcing  it  up, 
in  this  liquid  condition,  along  raised  carriers  on  to  land,  into 
which  it  is  subsequently  dug,  thereby  eventually  becoming 
incorporated  with  the  soil.  This  was  the  method  pursued  at 
Birmingham,  the  sewage  being  treated  with  lime,  and  the  effluent 
from  the  tanks  being  purified  by  irrigation  over  the  soil  of  the 
sewage  farm.  If  the  semi-liquid  sludge  is  allowed  to  dry  by 
exposure  to  the  air  in  pits,  it  generally  causes  a  nuisance,  so 
that  it  is  the  usual  practice  to  press  part  of  the  moisture  out  of 
the  sludge  by  hydraulic  filter  presses,  by  which  a  solid  cake,  con- 
taining from  50  to  60  per  cent,  of  moisture,  is  produced.  The 
pressed  sludge  can  be  stored  up  without  causing  any  nuisance, 
and  sold  or  given  away  according  to  the  demand  for  such  sewage 
manure.  It  may  be  further  dried  by  heating  in  drying  machines, 
and  then  ground  into  a  granular  condition,  when  it  generally 
contains  some  20  per  cent,  of  moisture.  In  this  condition  the 
manure  is  far  more  suitable  for  application  to  land  than  in  the 
form  of  the  coherent  masses  which  issue  from  the  filter  presses. 

Although  the  theoretical  value  of  a  ton  of  pressed  sludge 
cake  is  calculated  at  17s.,  the  actual  price  obtained  from  the 
sale  of  this  sludge  cake  varies  in  different  towns ;  in  some  there  is 
no  demand  for  it,  and  it  is  either  burnt  in  a  destructor  furnace, 
used  for  raising  low-lying  grounds,  or  even  a  small  premium  is 
paid  to  farmers  for  removing  it.  Owing  to  the  large  amount  of 
Hme  it  contains  its  actual  manurial  value  is  but  slight. 

Calculation. — State  approximately  the  amount  of  moist  sludge  containing 
90  per  cent,  of  moisture  that  can  be  precipitated  daily  from  the  sewage  of  a 
population  of  10,000,  with  a  water  supply  of  20  gallons  per  head  per  day. 

The  sewage  may  be  taken  as  equivalent  to  the  water  supply,  viz.,  20  x 

1  ,1-   1-  ■  1  ^     2,000,000 

10,000  =  200,000  gallons  per  day;  or  10  x  200,000  lb.  by  weight  = 

2,240 

=  892-86  tons.     We  will  suppose  that  in  every  100,000  parts  of  the  sewage 

40  parts  of  suspended  matter  can  be  precipitated  by  chemical  reagents. 

Then  the  dry  solids  precipitated  from  the  sewage  amount  to  x 

1 00, 000 
892-86  tons  =  o-357  ton,  and  the  moist  sludge  containing  00  per  cent,  of 
moisture  will  be  10  X  0-357=  3-57  tons. 


142  hygiene  and  public  health 

The  Biological  Purification  of  Sewage. 

The  chief  natural  agencies  concerned  in  the  purification  of 
organic  matter  are  micro-organisms.  It  is  almost  entirely  due 
to  such  organisms  that  organic  matter — whether  it  be  faeces 
deposited  on  the  surface  of  soil,  or  an  animal  body  buried  within 
it — eventually  becomes  resolved  into  invisible  and  harmless 
gases  and  mineral  ash,  for  sterihzed  organic  matter  remains 
undecomposed  for  indefinite  periods,  so  long  as  steriUty  is 
maintained. 

Ever  since  cesspools  were  employed  for  the  reception  of  the 
sewage  of  a  house,  it  has  been  noted  that  the  material  which  is 
periodically  emptied  out  of  the  cesspool,  or  which  overflows  from 
it,  is  a  liquid  containing  very  little  suspended  solid  matter. 
Sohd  matters  in  bulk  are  only  encountered  near  the  floor  of  the 
cesspool.  How  is  it  that  a  comparatively  small  cesspool,  with  an 
overflow  discharging  nothing  but  liquid  material  for  a  year  or 
more,  does  not  become  filled  with  the  large  amount  of  solid 
faecal  matter  daily  entering  it  ?  The  answer  is  that  micro- 
organisms in  countless  myriads  are  constantly  feeding  upon  this 
solid  matter,  and  converting  it  into  products  which  ultimately 
become  dissolved  in  the  liquid  part  of  the  sewage.  The  organisms 
which  effect  this  change  are  of  many  forms,  and  may  be  broadly 
classified  into  three  groups. 

1.  Those  which  work  in  the  absence  of  oxygen  (anaerobes). 

2.  Those  which  work  in  the  presence  of  oxygen  (aerobes). 

3.  Those  which  are  capable  of  working  either  in  the  presence 
or  absence  of  oxygen  (facultative  aerobes). 

Our  knowledge  of  the  last-named  group  is  not  sufficient  to 
enable  us  to  speak  with  certainty  as  to  the  part  they  play  in 
sewage  purification,  but  it  is  certain  that  both  the  aerobes  and 
anaerobes  are  concerned  in  the  resolution  of  organic  matter. 
With  regard  to  these  two  classes  of  organisms,  there  are  reasons 
for  believing  that  the  anaerobes  are  the  most  efficacious  in  causing 
the  liquefaction  of  the  solid  matter  contained  in  sewage.  Prior 
to  attack  by  these  liquefying  organisms,  the  sohd  organic  matter 
is  in  a  more  or  less  stable  condition;  but  as  the  result  of  their 
life  action  the  complex  organic  molecule  is  split  up  into  by- 
products, which  are  largely  soluble  and  unstable,  and  con- 
siderable quantities  of  gases  (CH4,  NH.^,  CO.,,  and  SH.,)  are 
evolved. 


DISPOSAL    OF    REFUSE  I43 

This  first  stage  of  purification  of  sewage  is  closely  analogous  to 
the  process  of  gastric  digestion,  whereby  the  organic  matter  is 
split  up  and  liquefied;  the  gelatinous  and  albuminoid  material 
undergoing  a  peptonizing  process,  and  the  non-nitrogenous 
substances  being  reduced,  and  finally  converted  into  COo  and 
HgO.  As  in  digestion,  also,  the  element  of  time  is  essential. 
The  organisms  must  not,  therefore,  be  asked  to  do  their  work  in 
too  short  a  time,  or  their  activity  will  be  unavaihng. 

The  second  stage  of  purification  is  doubtless  largely  performed 
by  the  aerobes,  and,  in  consequence,  every  effort  should  be  made 
to  set  them  their  work  under  conditions  favouring  an  abundant 
supply  of  available  oxygen.  The  more  or  less  stable  solid 
organic  matters  having  been  broken  up,  rendered  less  stable,  and 
thrown  into  solution  in  the  first  stage,  are  in  the  second  stage 
converted  into  the  ultimate  products  CO2,  NH3,  HoO,  and  traces 
of  SH.,;  nothing  ultimately  remaining  but  a  trivial  quantity  of 
mineral  matter,  rich  in  nitrates,  chlorides,  and  sulphates. 

It  is  only  in  recent  years  that  these  natural  agencies  of  puri- 
fication have  been  scientifically  utilized  in  the  disposal  of  sewage 
in  bulk,  but  we  have  already  arrived  at  such  a  stage  of  know- 
ledge that  some  remarkable  results  have  been  achieved.  The 
Royal  Commission  on  Sewage  Disposal,  appointed  in  1898, 
issued  an  Interim  Report  in  lyoi.  In  this  Report  they  state 
that  "It  is  practicable  to  produce  by  artificial  processes  alone, 
as  opposed  to  land  treatment,  either  from  sewage  or  from  certain 
mixtures  of  sewage  and  trade  refuse,  effluents  which  will  not 
putrefy,  which  would  be  classed  as  good  according  to  ordinary 
chemical  standards,  and  which  might  be  discharged  into  a 
stream  without  fear  of  creating  a  nuisance."  The  advantages 
often  gained  over  the  older,  or  what  may  be  termed  the  chemico- 
biological  method  (in  which  the  sewage  solids  are  first  precipi- 
tated by  chemicals,  the  comparatively  clear  effluent  being  then 
exposed  to  biological  agencies  in  filter  beds  or  in  land),  are 
obvious.  The  almost  useless  sludge  which  resulted  from  the 
chemical  treatment,  the  collection  and  ultimate  disposal  of 
which  entails  considerable  labour  and  expense,  is  reduced  to  a 
relatively  small  bulk  (in  the  septic  tank  quite  \  of  the  suspended 
matters  entering  the  tank  are  destroyed),  and  the  cost  of  the 
chemicals  and  of  their  appHcation  is  also  saved.  But  the 
greatest  gain  is  doubtless  often  in  the  direction  of  greater 
efficiency  of  treatment,  which  results  in  a  purer  and  sweeter 


144  HYGIENE    AND   PUBLIC   HEALTH 

effluent — one  more  readily  susceptible  to  the  agencies  of  ultimate 
purification,  and  more  valuable  to  vegetable  life. 

We  may  now  review  the  various  means  which  have  been 
adopted  for  utilizing  these  natural  agencies  in  sewage  purifica- 
tion. The  first  practical  attempt  to  solve  the  problem  was 
commenced  by  the  Massachusetts  Board  of  Health  in  1888. 
The  extensive  experiments  since  made  by  that  Board  have 
estabHshed  the  fact  that  intermittent  downward  filtration  through 
prepared  filters  of  suitable  material  will,  by  reproducing  the 
most  favourable  conditions  of  land  filtration,  achieve  all  the 
good  results  of  the  latter  on  a  much  smaller  area.  The  experi- 
ment showed  that  the  beds  need  not  be  of  a  greater  depth 
than  4  to  5  feet,  in  order  to  treat  satisfactorily  100,000  gallons 
of  sewage  to  the  acre  per  diem.  In  such  beds,  after  a 
week  or  two  of  sewage  treatment,  the  particles  of  filtering 
material  become  covered  with  thin  films  ("  colonies  ")  of  micro- 
organisms. 

Mr.  Scott- Moncrieff  was  the  first  (1891)  to  suggest  a  mode 
of  treatment  whereby  the  preliminary  liquefaction  of  solid 
matters  could  be  brought  about  in  a  separate  apparatus,  and 
the  purification  of  the  matter  in  solution  could  be  subsequently 
eifected.  This  mode  of  treatment  of  sewage  by  separating  the 
stages  of  its  purification  is  doubtless  advantageous,  seeing  that 
the  classes  of  organisms  concerned  in  the  prehminary  lique- 
faction are  distinct  from  those  concerned  in  the  subsequent 
purification,  and  each  class  exerts  its  powers  most  effectually 
when  kept  apart  from  the  other.  There  is,  moreover,  evidence 
that  the  second  stage  of  purification  itself  comprises  many 
subsidiary  stages,  and  that  special  classes  of  organisms  are 
concerned  in  these  several  stages. 

Almost  all  the  installations  at  present  in  use  embody  the 
principle  of  dividing,  to  a  greater  or  less  degree,  the  whole  pro- 
cess of  sewage  purification  by  natural  means  into  these  two 
stages:  Stage  I.  providing  essentially  for  liquefaction  of  solids, 
and  Stage  II.  for  subsequent  purification  of  the  unstable  and 
Hquid  products  of  Stage  I. 

The  installation  adopted  by  Mr.  Scott-Moncrieff  consisted 
of  two  or  more  tanks  ("  cultivation  tanks  ")  filled  with  large 
stones  below  and  smaller  ones  above.  The  sewage  is  allowed 
to  flow  slowly  and  continuously  into  a  false  bottom  on  the 
floor  of  the  tanks  and  to  escape  at  the  top.     In  its  upward 


DISPOSAL   OF   KEFUSE  I45 

passage  over  the  stones  the  solid  matters  of  the  sewage  arc  to 
a  large  extent  retained,  and  the  stones  become  coated  with 
anaerobic  liquefying  organisms  obtained  from  the  sewage. 
Under  the  influence  of  these  organisms  the  solids  of  the  sewage 
become  liquefied  to  such  an  extent  that  the  effluent  escaping 
from  the  top  of  the  tank  contains  but  very  little  suspended 
matter.  In  Stage  II.  of  purification  the  aim  is  to  bring  the 
sewage  under  the  most  favourable  aerobic  conditions  obtainable. 

To  this  end  the  tank  effluent  is  conducted  into  a  series  of 
channels  ("  nitrification  channels  ")  freely  exposed  to  the  air 
and  filled  with  large  stones,  which  serve  the  double  purpose  of 
breaking  up  the  current  of  liquid  (and  thereby  helping  to  thor- 
oughly aerate  it),  and  also  of  affording  surfaces  on  which  the 
aerobic  organisms  can  plant  themselves  in  great  numbers. 

More  recently  Mr.  Scott-Moncrieff  designed  means  of  securing 
an  even  more  complete  aeration  of  the  effluent  from  the  tank  by 
the  use  of  a  series  of  perforated  trays  containing  filtering  media, 
placed  at  intervals  of  a  few  inches  one  above  another,  so  that  the 
liquefied  sewage  delivered  over  the  surface  of  the  top  tray  tricldes 
slowly  from  tray  to  tray  to  the  ultimate  outfall  in  the  effluent 
collecting  channel. 

It  is  probable,  as  claimed  by  the  inventor,  that  the  organisms 
in  the  different  trays,  having  to  deal  with  sewage  in  different 
stages  of  purification,  become  differentiated,  and  therefore  work 
to  the  best  advantage. 

He  also  advocates,  where  possible,  the  addition  to  the  effluent 
from  the  trays  of  a  certain  volume  of  well-oxygenated  water. 

Kenwood  and  Butler  found  from  an  extensive  series  of 
experiments  performed  upon  an  installation  of  a  modified 
Scott-Moncrieff  anaerobic  tank  at  Finchley,  that  there  was  a 
continuous  reduction  of  the  more  stable  organic  matter  to 
unstable  organic  compounds,  and  subsequent  production  of  the 
ultimate  products  of  anaerobic  organic  decomposition. 

A  microscopical  examination  of  the  small  amount  of  matter 
retained  in  the  tank  disclosed  the  presence  of  fine  granular 
debris  which  was  rich  in  iron,  particles  of  silica  and  carbon, 
algoid  growths  (some  with  chlorophyll  and  others  without), 
a  few  live  protozoa  and  rotifers,  vegetable  hairs,  bundles  of 
vegetable  fibres,  large  numbers  of  vegetable  spiral  vessels, 
zoogloea,  an  ovum  of  tienia,  a  few  striated  muscle  fibres,  cotton 
fibres,  and  human  hairs. 

10 


146  HYGIENE    AND    PUBLIC   HEALTH 

By  experiments  on  a  septic  tank,  or  hollow  chamber,  on  a 
small  scale,  they  found  that  the  same  changes  which  occurred  in 
Scott-Moncrieff's  anaerobic  filter  tank  took  place  in  a  hollow 
septic  tank,  only  somewhat  more  slowly. 

Extensive  experiments  by  Mr.  Dibdin  from  1891  to  1895 
with  the  Metropolitan  sewage  led  to  his  advocacy  of  what  is 
known  as  the  Sutton  system  of  biological  purification.  The 
sewage  is  first  strained  of  large  particles  by  means  of  fine  metal 
strainers  introduced  at  the  sewer  outfall,  where  the  sewage 
enters  the  works;  it  is  then  exposed  to  downward  filtration 
through  coarse  beds.  It  is  in  these  coarse  beds  that  liquefaction 
should  take  place.  They  arc  4  feet  deep,  and  made  of  coarse 
burnt  ballast  of  particles  of  such  a  size  that  they  will  pass 
through  a  2-inch  ring,  but  are  rejected  by  a  |-inch  mesh;  the 
object  of  using  such  coarse  material  being  to  admit  the  solid 
particles  of  crude  sewage  into  the  body  of  the  bed,  and  also  to 
favour  thorough  aeration  when  the  liquid  sewage  is  drawn  off. 
The  coarse  material,  moreover,  does  not  get  so  readilj^  clogged. 
The  efiiuent  from  the  coarse  bed  is  then  conveyed  on  to  the 
surface  of  a  fine  filter  4  feet  deep,  constructed  of  particles  which 
will  pass  a  J-inch  mesh,  but  which  are  rejected  by  one  of  ^V  inch. 

The  sewage  is  allowed  to  fill  these  beds  almost  to  their  top 
surfaces,  and  then  to  rest  in  them  for  a  period  of  two  hours 
(hence  they  are  known  as  contact  beds).  Then  the  beds  are 
slowly  emptied  and  allowed  to  remain  at  rest  for  several  hours, 
so  that  several  of  such  filters  are  necessary  in  even  a  small 
installation.  Each  filter-bed  is  filled  up  thrice  daily.  This  inter- 
mittent application  of  the  sewage  insures  also  a  certain  amount 
of  aeration  of  the  beds.  One  drawback  to  the  use  of  the  coarse 
or  "  roughing  "  filter  is  the  fact  that  the  upper  stratum  of  the 
filtering  material  becomes  clogged  at  intervals  with  a  black 
deposit  of  solid  matter.  The  surface  of  such  filters,  therefore, 
requires  occasional  raking  or  ploughing. 

The  practice  of  applying  the  crude  sewage  by  a  single  carrier 
to  a  coarse  continuous  bed  would  have  the  effect  of  ov'ertaxing 
the  bed  on  either  side  of  the  trough,  for  the  material  there  will 
collect  more  than  its  share  of  suspended  matter  whilst  the  bed 
is  filling;  such  a  filter,  therefore,  is  not  given  the  best  chance 
of  carrying  on  its  work. 

Kenwood  and  Butler  found  that  in  installations  upon  Dibdin's 
principle  with  coarse  and  fine  contact  beds,  a  greater  area  of 


DISPOSAL   OF    REFUSE  I 47 

coarse  filter  than  of  Hue  liiter  should  be  provided,  and  that  the 
sewage  should  be  locked  up  for  longer  periods  (4  hours)  in  the 
coarse  beds,  and  shorter  periods  (2  hours)  in  the  hne  beds.  It  is 
in  the  coarse  beds  that  the  liquefaction  of  the  solid  matter  takes 
place,  and  the  stability  of  the  organic  matter  in  solution  is 
shaken,  and  time  is  the  all-important  element  in  bringing  about 
these  changes.  Their  experiments  also  demonstrated  the  fact 
that,  for  the  second  stage  of  purification,  the  transference  of  the 
sewage  from  one  bed  to  another  in  a  series  of  two  or  three  beds 
brought  about  a  higher  degree  of  purification  in  a  shorter  time 
than  prolonged  treatment  in  one  bed  alone. 

The  "  septic  tank  "  method  was  devised  by  Mr.  Cameron  of 
Exeter  at  about  the  same  time  that  Mr.  Dibdin's  experiments 
were  in  progress. 

The  method,  like  that  of  Mr.  Scott-Moncrieff,  provides  for 
a  well-defined  line  of  demarcation  between  the  stages  of  lique- 
faction and  of  subsequent  purification.  Provision  is  made  for 
liquefaction  under  strictly  anaerobic  conditions  in  a  large  covered 
receptacle  provided  with  an  inlet  for  the  sewage  and  an  outlet 
for  the  tank  effluent.  The  sewage  travels  so  slowly  through 
the  tank  that  every  particle  takes  some  twenty-four  hours  in 
passing  through  it.  This  period  of  time  is  sufficient  for  such  a 
complete  sedimentation  and  liquefaction  of  solids  to  be  effected 
that  the  tank  effluent  should  contain  but  a  few  grains  per 
gallon  of  fine  suspended  matter.  The  black  deposit  which 
settles  in  the  bottom  of  the  tank  was  found  after  fifteen  months' 
working  to  be  under  2  feet  in  depth.  This  deposit  consists  of 
indigestible  material,  and  includes  mineral  matter,  cellulose, 
vegetable  and  elastic  fibres,  cartilage  cells,  etc.  The  gases  given 
off  from  the  tanks  are  not  offensive,  but  are  highly  inflammable. 
The  mixture  of  gases  contains  (Rideal)  C02  =  o-6,  methane  = 
24*4,  hydrogen  =  36-4,  nitrogen  =  38-6,  in  100  parts. 

The  second  stage  of  purification  is  effected  by  passing  the 
dark  coloured  tank  effluent  through  an  "  aerator  " — a  long 
trough  over  the  edges  of  which  the  liquid  falls  in  thin  films, 
thereby  mechanically  entanghng  a  certain  quantity  of  air; 
and  from  thence  on  to  a  series  of  coke-breeze  filters  4I  feet  deep. 
These  filters  are  filled,  rested  while  full,  slowly  emptied,  and 
rested  for  several  hours  while  empty,  in  the  manner  advocated 
by  Mr.  Dibdin.  The  effluent  from  the  tank  is  applied  to  the 
filters  in  rotation  by  an  ingenious  automatic  arrangement,  which 


148  HYGIENE   AND    PUBLIC   HEALTH 

removes  the  necessity  for  continuous  manual  attention.  The 
practice  at  Exeter  leads  to  about  six  hours  being  consumed  in 
the  filling  of  each  filter,  which  then  remains  full  for  six  hours; 
the  filter  is  then  emptied  in  half  an  hour,  and  is  allowed  to 
remain  at  rest  for  the  remainder  of  the  twenty-four  hours  {i.e., 
eleven  and  a  half  hours).  The  Local  Government  Board  has 
since  sanctioned  a  scheme  for  the  treatment  of  the  whole  of 
the  Exeter  sewage  on  similar  lines. 

When  sewage  is  allowed  to  flow  slowly  through  an  open  tank, 
a  thick  spongy  scum  gradually  covers  the  surface.  The  eftluents 
furnished  by  similar  sewage  from  an  open  "  scum  "  tank  and 
a  closed  septic  tank  are  very  similar  to  each  other.  The  scum 
provides  a  cheap  roof  which  preserves  the  heat  in  the  sewage  and 
thereby  promotes  bacterial  action,  and  also  tends  to  prevent  the 
dissemination  of  smell  from  the  tanks.  One  may  broadly  sum- 
marize the  advantages  of  anaerobic  tanks  as  follows:  They  pro- 
mote uniformity  of  effluent ;  they  permit  of  the  digestion  of  from 
30  to  40  per  cent,  of  the  suspended  solids  of  sewage,  with  the 
result  that  such  solids  in  the  tank  effluent  rarely  exceed  15 
to  20  parts  per  100,000;  the  stability  of  most  of  the  organic 
solids  is  rapidly  reduced  by  a  short  sojourn  in  a  tank,  and 
subsequent  purification  thereby  much  facilitated. 

The  difficulties  often  arising  from  the  treatment  of  the  highly 
offensive  efiluent  from  a  septic  tank  led  Dibdin  to  advocate  the 
preliminary  treatment  of  crude  sewage  in  slate  beds,  in  which 
it  is  only  retained  for  two  hours,  so  that  it  emerges  in  a  fresh 
condition.  The  slates,  which  are  the  refuse  of  slate  quarries, 
are  laid  horizontally  in  layers  about  2^  inches  apart,  in  a  bed 
about  4  feet  deep.  The  slates  are  supported  on  small  slate  slabs 
of  the  required  thickness.  These  beds  are  filled  from  the  top, 
and  emptied  from  the  bottom,  the  sewage  remaining  at  rest 
for  two  hours,  and  the  beds  being  left  empty  for  a  like  period. 
This  process  is  now  at  work  at  Devizes,  where  the  ciiide  sewage 
is  very  strong,  and  is  mixed  with  the  refuse  from  breweries.  The 
effluent  from  the  slate  beds  is  clear  and  inodorous,  and  is  in  a 
condition  very  suitable  for  application  to  the  contact  beds  of 
fine  clinker,  in  which  the  process  of  purification  is  completed. 
A  certain  amount  of  silt  from  the  sewage  is  deposited  on  the 
slates,  but  the  amount  so  collected  is  not  large,  and  it  has  not 
been  found  necessary  to  wash  out  the  silt  more  frequently  than 
once  or  twice  a  year.    The  deposited  silt  soon  loses  any  sewage 


DISPOSAL   OF   REFUSF.  I49 

odour,  and  has  the  character  of  rich  mould  when  taken  from  the 
slates,  with  a  strong  earthy  smell. 

Slate  bed  installations  have  been  successfully  adopted  in 
many  places  of  recent  years,  and  have  been  found  to  give  satis- 
factory results.  Where  the  sewage  is  abnormally  strong,  and 
the  faecal  matter  has  had  no  time  to  disintegrate,  as  in  barrack 
sewage,  and  especially  in  barracks  where  there  is  much  stable 
drainage,  the  quantity  of  suspended  matter  is  often  so  great  as 
to  choke  the  lower  portion  of  the  slate  beds,  with  the  result  that 
putrefaction  occurs,  and  the  lastl  portion  of  the  slate  bed  effluent 
is  highly  offensive.  In  such  installations  the  crude  sewage 
should  be  sedimented  in  detritus  tanks  before  passing  to  the 
slate  beds ;  and,  if  the  slate-bed  effluent  contains  much  suspended 
matter,  it  should  be  made  to  flow  through  a  shallow  "  humus  " 
bed  to  deposit  the  fine  sediment,  before  it  is  distributed  to 
contact  beds  or  aerating  filters.  In  this  way  the  tendency  of 
secondary  filter  beds  to  become  clogged  with  humus  from  a  slate 
bed  effluent  may  be  counteracted.  The  great  advantage  of  the 
slate  beds  in  a  satisfactory  installation  is  that  the  primary 
effluent  is  inoffensive,  and  much  less  liable  to  create  a  nuisance  on 
secondary  treatment,  than  is  the  septic  effluent  from  a  septic  tank. 

In  Colonel  Ducat's  method  the  stages  of  liquefaction  and 
subsequent  purification  go  on  continuously  side  by  side  in  the 
same  apparatus.  A  filter  some  8  feet  in  depth,  and  varying  in 
area  with  the  amount  of  sewage  it  is  required  to  treat,  is  built 
up  from  the  ground  level  with  walls  composed  of  agricultural 
drain  pipes,  arranged  so  that  their  long  axes  are  directed  (with 
a  slight  fall)  towards  the  interior  of  the  filter.  By  this  arrange- 
ment the  wind,  from  whatever  direction,  can  blow  into  the  body 
of  the  filter,  whereas  the  slope  of  the  pipes  prevents  the  sewage 
from  flowing  out  of  them.  The  body  of  the  filter  is  formed  of 
layers  of  coke,  large  at  the  top  and  small  below,  each  layer, 
which  is  about  i8  inches  deep,  being  separated  from  its  neigh- 
bours by  an  aerating  layer  of  big  stones  and  of  pipes.  Dis- 
tributing troughs  apply  the  sewage  evenly  over  the  top  of  the 
filter,  through  which  it  slowly  passes,  the  effluent  finally  collecting 
in  a  channel  which  surrounds  the  bottom  of  the  filter. 

Colonel  Ducat  also  devised  means  of  warming  his  filter  in 
the  winter,  thus  providing  against  the  effects  of  frost,  and 
also  insuring  a  constant  temperature  specially  favourable  to 
the  work  of  the  micro-organisms. 


150  HYGIENE    AND    PUBLIC   HEALTH 

This  process  has  furnished  satisfactory  results  in  practice; 
but  it  is  difficult  to  believe  that  this  would  generally  be  the  case, 
seeing  that,  the  process  being  one  of  continuous  action,  the 
essential  and  all-important  element  of  time  is  not  sufficiently 
provided  for  the  "  digestion  "  which  by  other  methods  forms 
the  preliminary  state  of  sewage  treatment. 

When  an  installation  is  provided  for  the  natural  purification 
of  sewage,  the  organisms  concerned  in  the  process  are  planted 
on  the  filters,  etc.,  by  the  sewage  itself;  but  it  is  not  until  after 
the  sewage  has  been  applied  to  the  installation  for  many  days 
that  the  organisms  have  become  sufficiently  developed  and 
differentiated  to  produce  their  best  effects. 

In  installations  of  the  "  septic  tank  "  or  the  Scott-Moncrieff 
tank,  the  provision  made  must  be  sufficient  to  hold  at  least  one 
day's  sewage  flow.  The  matter  is,  however,  complicated  by 
the  necessity  of  making  provision  for  some  at  least  of  the  storm 
water,  which  may  at  times  swell  the  dry  weather  flow,  for  during 
rainy  periods  the  volume  of  sewage  is  often  more  than  quad- 
rupled. The  Local  Government  Board  requires  that  storm 
water  amounting  to  thrice  the  dry  weather  flow  of  sewage  must 
be  treated  in  every  respect  as  the  sewage,  while  any  additional 
quantity  of  storm  water  up  to  six  times  the  dry  weather  flow 
must  receive  special  treatment,  either  by  means  of  an  artificial 
filter  or  by  land  used  for  no  other  purpose.  The  storm  water 
over  and  above  six  times  the  dry  weather  flow  may  be  discharged 
into  a  stream.  Local  authorities  must  therefore  make  provision 
for  the  treatment  of  six  times  the  dry  weather  flow.  Special 
storm  water  filters  of  burnt  ballast,  etc.,  will  deal  satisfactorily 
with  500  gallons  of  dilute  sewage  to  each  superficial  yard  of 
filter  area  (2,420,000  gallons  per  acre)  per  diem. 

Aerating  filler-heds  must  be  constructed  of  fine  grain  material. 
The  nature  of  this  material,  given  that  it  is  hard  and  durable, 
does  not  appear  to  be  a  matter  of  prime  importance.  It  may  be 
of  coal,  cinders,  coke,  clinker,  saggars  (refuse  potter}'),  burnt 
ballast,  gravel,  or  flint,  and  local  circumstances  may  be  left  to 
determine  which  to  select.  Coke  is  generally  scarce  and  ex- 
pensive, coal  is  expensive,  and,  like  burnt  ballast,  gravel,  and 
flint,  can  often  only  be  obtained  by  the  payment  of  heavy  charges 
for  carriage.  Sand  and  gravel  do  not  appear  to  be  so  satisfactory 
as  filters  of  clinker,  coke,  coal,  and  burnt  ballast.  In  order  to 
secure  good  and  uniform  results,  the  filters  should  never  be  made 


DISPOSAL   OF    REFUSE  151 

to  deal  with  more  than  a  million  gallons  of  average  sewage  per 
acre  per  diem  (about  200  gallons  per  superficial  yard).  The  water 
capacity  of  these  fine  grain  beds  diminishes  somewhat  with  use 
owing  to  the  retention  of  solid  sediment,  until  as  a  rule  a  stage 
of  equilibrium  is  reached,  when  the  liquid  capacity  of  tlie  bed 
generally  averages  about  33  per  cent,  of  the  total  cubic  capacity. 

Contact  beds  of  coarse  coke-breeze  or  burnt  ballast,  used  to 
receive  crude  sewage,  separate  a  large  proportion  of  the  sus- 
pended matter  of  the  sewage;  hence  their  capacity  for  liquid 
generally  settles  down  to  a  smaller  proportion,  represented 
commonly  by  an  average  figure  of  25  per  cent.  The  eight  hours 
cycle  of  treatment  of  these  filter-beds  meets  with  the  approval 
of  the  Local  Government  Board,  the  time  being  allotted  as 
follows:  I  hour  to  fill,  2  hours  to  rest  full,  i  hour  to  empty,  and 
4  hours  to  rest  empty.  It  has  now  been  proved  that  such 
contact  beds  can  be  worked  at  the  rate  of  1,000,000  gallons  per 
acre  per  diem,  if  the  eight  hours'  cycle  is  strictly  maintained. 

In  all  natural  processes  of  sewage  purification  the  sewage  must 
first  of  all  be  passed  through  a  grit  or  detritus  chamber  in  order 
to  retain  large  mineral  particles,  which  would  otherwise  find 
their  way  into  the  installation  and  accumulate  there,  organisms 
being  of  course  quite  incapable  of  attacking  them. 

What  is  essential  in  the  working  of  a  natural  process  is  for 
the  superintendent  of  the  works  to  fully  appreciate  that  he  hcS 
countless  colonies  of  living,  working  units  under  his  control. 
Their  work  must  always  be  regulated  according  to  their  powers, 
and  sufficient  and  periodical  intervals  of  rest  must  be  allowed 
them  between  the  regular  periods  of  work.  Then,  and  then 
only,  will  they  attune  their  powers  to  the  work  they  are  called 
upon  to  perform,  and  so  establish  that  equilibrium  between 
intake  and  output  which  is  so  easy  to  maintain,  and  so  difficult 
to  regain  when  once  lost. 

It  is  an  interesting  matter  to  note  that  the  total  nitrogen  in 
organic  combination  in  the  sewage  which  enters  any  of  these 
installations  is  not  nearly  accounted  for  in  the  NH3,  nitrates, 
nitrites,  and  the  organic  nitrogen  still  remaining  in  the  final 
effluent.  The  loss  is  doubtless  due  to  the  fact  that  free  nitrogen 
passes  away  from  the  beds,  possibly  also  oxides  of  nitrogen,  and 
a  considerable  amount  of  ammonia. 

On  the  ground  that  the  micro-organisms  concerned  in  oxida- 
tion and  nitrification  of  organic  matters  are  so  dependent  on 


152  HYGIENE    AND   PUBLIC  HEALTH 

oxygen,  that  they  will  even  reduce  chemical  compounds  in 
order  to  use  their  available  oxygen,  Adeney  advocates  the 
addition  to  the  sewage  of  small  quantities  of  an  agent  contain- 
ing available  oxygen,  such  as  nitrate  of  soda  or  the  manganate 
of  soda.  With  the  same  object  Lowcock  has  devised  a  filter 
of  sand  and  gravel  which  is  kept  aerated  by  pumping  air  into  it, 
and  which  can  be  used  continuously  with  good  results. 

The  intermediate  flushing  of  the  filter-beds  with  water  has  been 
advocated  by  Lomain,  Barwise,  and  others,  and  where  prac- 
ticable there  is  every  reason  to  believe  that  a  gain  would  result ; 
for  there  is  a  general  tendency  for  matter  in  colloidal  solution 
and  fine  suspended  matter  to  deposit  and  unduly  accumulate 
upon  the  filter,  thereby  impairing  the  working  efficiency  of  the 
filter,  reducing  the  quality  of  the  effluent,  and  entailing  con- 
siderable cost  in  its  removal.  Bostock  Hill  advocates  the  use 
of  coal  asa  filtering  material  (Garfield's  filter),  the  particles  of 
coal  being  about  the  size  of  |-inch  cubes  at  the  bottom  of  the 
filter,  and  becoming  smaller  towards  the  top. 

When  certain  trade  effluents,  especially  waste  acids,  are 
passed  into  town  sewage,  experiment  alone  can  decide  whether 
it  will  be  necessary  to  employ  a  preliminary  chemical  (lime) 
treatment  prior  to  bacterial  treatment  in  filter-beds.  It  is 
certain  that  the  natural  agencies  of  purification  are  for  the  most 
part  capable  of  dealing  with  such  quantities  of  the  trade  effluents 
as  more  usually  find  their  way  into  sewage.  It  would,  however, 
be  advantageous  if  manufacturers  could  be  made  to  distribute 
the  discharge  of  trade  wastes  more  equally  over  the  twenty-four 
hours;  and  in  some  cases  the  waste  products  should  undergo 
some  purification  or  treatment  before  they  are  permitted  to 
leave  the  premises  on  which  they  are  produced. 

Trade  effluents  may  be  objectionable  by  reason  of  the  presence 
of  excessive  amounts  of  suspended  matter,  such  as  lime,  clay, 
shale,  fibre,  fine  stone,  or  coal,  etc.  In  most  cases  the  suspended 
matter  may  be  removed  by  simple  subsidence  in  suitably  con- 
structed settling  tanks,  aided,  if  necessary,  by  the  addition  of 
such  chemicals  as  lime,  copperas,  or  alumino-ferric.  Fine  screens 
or  specially  adapted  straining  filters  may  be  necessary  in  some 
cases. 

The  introduction  of  brewery,  tannery,  glue- factory,  etc.,  waste 
into  sewage  is  often  productive  of  nuisance  in  the  subsequent 
processes  of  treatment,  more  especially  in  the  case  of  small  towns, 


DISPOSAL    OF    REFUSE  I53 

where  the  brewery  waste  forms  a  considerable  proportion  of  the 
total  volume  of  liquid  carried  to  the  outfall  sewer.  The  brewery 
waste  has  an  aromatic  odour,  which  is  penetrating  and  dis- 
agreeable, and  is  sometimes  perceptible  at  a  considerable  dis- 
tance from  the  sewage  works.  In  such  cases  it  may  be  desirable 
to  have  the  septic  tanks  covered  over,  and  not  to  employ 
sprinklers  to  distribute  the  tank  effluent  over  the  streaming  or 
aerating  filters,  as  the  wind  passing  through  the  effluent  issuing 
from  the  sprinklers  may  convey  smell  to  a  distance.  If  the  sewage 
works  are  in  the  neighbourhood  of  dwellings,  primary  and 
secondary  contact  beds  are  less  likely  to  be  productive  of  nuisance 
than  sprinkler  beds ;  and  if  streaming  filters  are  to  be  used,  fixed 
distributors  will  be  preferable  to  revolving  sprinkhng  arms. 
But  it  is  generally  preferable  to  obtain  some  treatment  of  such 
trade  effluents  before  they  are  admitted  to  the  pubhc  sewer. 
They  may  be  purified,  with  or  without  preHminary  dilution,  by 
lime;  and,  after  precipitation,  they  may  be  passed  through  filter 
beds  or  applied  to  land. 

Sewage  rich  in  fatty  and  soapy  matters,  as  in  districts  where 
certain  manufactories  and  laundries  are  numerous,  is  very 
retractable  to  purification  by  biological  agencies.  The  fat  is 
especially  resistant  and  tends  to  coat  the  particles  of  which 
the  aerating  beds  are  composed,  thereby  reducing  their  biological 
efficiency,  and  presenting  obstacles  to  the  passage  of  the  sewage 
through  a  fine  filter.  Trade  effluents  containing  much  fat  should 
be  treated  before  being  passed  into  the  public  sewers.  The  fat 
may  be  largely  removed  by  suitably  constructed  grease-traps, 
or  recovered  by  treatment  with  acid  or,  in  the  ca.se  of  soap,  with 
lime. 

Kenwood  and  Butler  found  that  a  fi.lter  soon  acquires  a  state 
of  equilibrium,  as  regards  powers  of  purification,  which  tends 
to  adjust  itself  to  the  average  strength  of  the  polluting  material 
with  which  it  is  day  by  day  being  suppHed.  It  is  for  this  reason 
that  the  necessity  for  multiple  filters  is  so  great  where  strong,  or 
alternating  weak  and  strong,  sewages  have  to  be  dealt  with ;  for 
a  filter  will  effect  only  a  certain  percentage  reduction  of  the 
polluting  ingredients  of  the  sewage  it  receives,  even  when  it 
has  reached  its  maximum  biological  efflciency. 

The  point  always  to  be  borne  in  mind  is  that  what  has  to  take 
place  is  not  merely  the  reduction  of  unstable  matter  to  ultimate 
products,  but  the  reduction  of  the  more  stable  organic  matter 


154  HYGIENE   AND    PUBLIC    HEALTH 

to  the  unstable.  The  reduction  of  the  unstable  to  the  ultimate 
appears  to  be  best  effected  by  change  of  filters,  that  of  stable  to 
unstable  by  rest  in  a  filter. 

Drs.  Clowes  and  Houston  advocate  the  use  of  coke  for  contact 
filters  in  pieces  of  about  the  size  of  walnuts,  as  the  larger  pieces 
enable  the  bed  to  hold  a  larger  volume  of  sewage  and  to  be 
more  rapidly  filled  and  emptied,  as  well  as  more  effectively 
emptied  and  aerated.  They  find  that  in  a  bed  13  feet  in  depth 
the  purification  approximates  to  that  in  one  4  feet  deep. 

A  bacterial  filter  of  coke  will  cost  from  ;,r2,ooo  to  £4,000  per 
acre,  and  each  acre  will  treat  from  500,000  to  1,000,000  gallons 
daily,  according  to  the  nature  of  the  sewage. 

The  amount  of  purification  exerted  by  a  filter  or  installation 
may  be  expressed  as  a  percentage  calculated  upon  the  reduction  in 
the  albuminoid  ammonia  and  oxygen  absorbed  figures  of  the 
liquids  before  and  after  treatment.  In  many  installations  such 
purification  amounts  to  over  80  per  cent,  of  the  original  pollu- 
tion. 

If  the  aeration  beds  (commonly  known  as  streaming  filters) 
are  treated  intermittently  (and  excellent  results  can  be  got  by 
this  method),  then  the  sewage  must  be  applied  evenly  and  equally 
over  the  whole  area  of  the  filter.  It  is  difficult  to  effect  this 
with  ordinary  fixed  trough  distributors;  but  it  can  be  provided 
for  by  means  of  revolving  sprinkling  arms,  such  as  Candy's,  or 
the  Fiddian  Rotary  Distributor,  which  automatically  revolve 
horizontally  over  a  circular  bed,  the  motive  power  being  loss  of 
head  (about  i  foot)  by  the  passage  of  the  sewage  on  its  way  to 
the  sprinkling  arms.  Stoddart's  distributor  consists  of  a  gal- 
vanized iron  channel  furrowed  with  numerous  narrow  gutters  in 
close  parallel  rows.  Along  the  under  surface  of  each  gutter  is  a 
series  of  small  perforations  terminating  in  vertical  points.  The 
clarified  sewage,  entering  these  gutters,  forms  drops  upon  each 
of  the  vertical  points  which  drip  steadily  on  to  the  filter-bed 
immediately  below.  Streaming  filters  are  more  expensive  to 
construct  and  maintain  than  contact  beds,  and  are  more  often  a 
nuisance  from  flies.  The  chief  source  of  the  white-winged  fly,  so 
common  on  many  coarse  percolating  filters,  is  the  accumulation 
of  undigested  suspended  and  colloidal  matter  with  gelatinous 
growths,  which  occur  immediately  below  the  surface  of  perco- 
lating or  streaming  filters. 

The  methods  of  distribution  of  tank  cftluent  over  filter-beds 


DISPOSAL   OF    REFUSE  I55 

by  means  of  elongated  water-wheels,  which,  pivoted  at  the  centre, 
roll  bodily  over  the  surface  of  a  filter  on  circular  rail-tracks  laid 
around  the  circumference  of  the  filter,  or  by  travelling  distri- 
butors, in  which  the  watcr-whcels  pass  backwards  and  forwards 
over  rectangular  beds,  are  far  preferable,  from  the  point  of  view- 
both  of  even  and  regular  distribution  of  the  effluent  over  the 
filter,  and  also  of  lessened  likelihood  of  nuisance,  to  the  revolving 
sprinklers  and  fixed  nozzle  distributors.  In  the  water-wheel 
distributor,  the  effluent  falls  in  thin  sheets,  and  has  but  little 
depth  of  air  to  traverse,  the  water-wheel  being  close  down  upon 
the  bed,  unlike  the  fountain  sprays  of  the  sprinkler  and  nozzle 
distributors.  Consequently  there  is  less  risk  of  effluvia  being 
conveyed  b)^  winds  to  considerable  distances. 

In  Messrs.  Whittaker  and  Bryant's  installation,  as  the  sewage 
passes  to  the  sprinkler  a  jet  of  steam  is  blown  through  it,  which 
raises  its  temperature,  the  bacterial  bed  being  thereby  kept  at 
an  equable  temperature  very  favourable  to  the  activity  of  bac- 
teria. It  is  also  claimed  that  the  application  of  the  warm 
sewage  to  the  surface  of  the  bed  causes  an  expansion  of  the  air 
between  the  filtering  particles;  and,  as  a  consequence,  fresh  air 
is  drawn  through  the  drain  pipes  at  the  bottom  of  the  filter, 
and  made  to  traverse  the  body  of  the  bed,  a  high  degree  of  aera- 
tion being  thus  assured.  It  is  said  that  such  a  bed  can  deal  with 
600  gallons  of  sewage  per  square  yard  in  twenty-four  hours 
(2,904,000  gallons  per  acre). 

The  artificial  warming  of  bacterial  beds,  though  it  increases 
bacterial  activity,  is  not  necessary;  for  even  in  the  coldest 
winter  months  the  temperature  of  the  body  of  the  beds  rarely 
falls  below  50°  F.,  though  the  temperature  of  the  atmosphere 
may  be  below  40°  F. 

It  may  be  taken  for  granted  that  circumstances  favouring 
high  oxygenation  promote  the  ultimate  changes  of  purification 
and  the  production  of  an  effluent  with  good  physical  characters 
— incapable  of  putrefaction  and  of  developing  odour.  Efficient 
oxygenation  is  aimed  at  in  the  system  of  emptying  and  filling 
fine  bacterial  beds  in  Dibdin's  method,  in  the  aerating  channels 
and  beds  of  the  "  septic  tank  "  method,  in  the  nitrifying  channels 
and  trays  of  Scott-Moncrieff,  in  the  Ducat  filter,  Stoddart's 
distributor,  Lowcock's  filter,  Adeney  and  Parry's  suggestions 
for  the  addition  of  small  quantities  of  an  oxidizing  agent  in 
the  effluent,  and  in  the  use  of  sprinklers  and  water-wheel  dis- 


156  HYGIENE   AND   PUBLIC   HEALTH 

tributors.  Contact  beds  do  not  secure  oxygenation  of  the  effluent 
so  well  as  some  of  the  other  methods  in  practice;  and  observa- 
tions go  to  show  that  the  best  results  are  to  be  obtained  by  an 
intermittent  application  of  the  previously  sedimented  sewage 
upon  a  bed,  which  is  unenclosed,  or  the  outlet  pipe  of  which, 
when  enclosed  by  a  retaining  wall,  is  constantly  open  (streaming 
filters). 

With  the  evidence  at  present  available,  it  is  extremely  difficult 
to  decide  as  to  the  respective  merits  of  all  of  the  installations 
which  have  been  advocated.  Sewage  varies  so  much  in  its 
characters,  and  in  the  relative  proportions  of  its  different  con- 
stituents, that  experiments  performed  on  different  sewages 
afford  no  precise  information  on  which  can  be  based  a  safe  and 
scientific  comparison. 

Any  opinion  expressed  must,  therefore,  be  accepted  with 
reservation,  but  probably  every  one  of  the  methods  referred  to 
may  be  made  to  give  satisfactory  results.  Questions  of  economy 
of  plant  and  of  time,  of  working  and  maintenance,  and  of  the 
relative  applicability  of  the  process  to  local  wants  and  conditions, 
must  and  will  ultimately  determine  the  choice. 

There  is  no  evidence  of  the  ehmination  of  the  micro-organisms 
characteristic  of  sewage  by  anj^-  process  of  filtration  in  bacterial 
filter-beds.  It  is  evident,  then,  that  such  processes  can  in  no 
sense  be  regarded  as  effectual  in  preventing  danger,  where  filter 
effluents  are  discharged  into  streams  used  for  water  supply,  into 
water  where  water-cress  is  grown,  or  into  estuaries  where  oysters 
are  laid. 

The  Royal  Commission  on  Sewage  Disposal  appointed  in  1898 
reported  at  the  end  of  1903  that  they  were  satisfied  that  the 
consumption  of  shell-fish  specifically  polluted  by  sewage  may 
cause  enteric  fever  and  other  illnesses,  and  that  bacteriology 
at  present  cannot  be  relied  upon  to  determine  whether  or  not 
shell- fish  are  so  polluted.  It  is,  however,  a .  fact  that  a  very 
much  smaller  number  of  Bacilli  colt  or  coli-like  microbes  are  found 
in  oysters  stored  in  pure  water  than  in  those  stored  in  polluted 
waters.  In  the  opinion  of  the  Royal  Commission  tidal  waters 
should  be  placed  under  the  jurisdiction  of  some  competent 
authority,  whose  duty  it  would  be  to  see  that  where  shell-fish 
are  collected,  fattened,  or  stored,  there  is  no  risk  of  dangerous 
contamination.  They  further  recommend  that  in  respect  of 
imported  shell-fish  similar  precautions  should  be  demanded  as 


DISPOSAL   OF    REFUSE  I57 

a  condition  of  their  importation  to  this  country;  and,  in  default, 
all  imported  shell-lish  should  be  deposited  in  registered  layings 
for  at  least  six  weeks  antecedent  to  their  disposal  on  the  market. 

The  same  Royal  Commission  reported  in  1901,  that  while  in 
the  case  of  sewage  effluents  from  land  which  is  of  a  kind  suitable 
for  the  purification  of  sewage,  there  are  fewer  micro-organisms 
of  intestinal  origin  than  in  the  effluents  from  most  artificial 
processes,  yet  any  sewage  effluent  must  be  regarded  as  potentially 
dangerous.  In  conclusion  they  say  that  the  general  protection 
of  our  rivers  is  a  matter  of  such  grave  concern  as  to  demand  the 
creation  of  a  separate  Commission,  or  a  new  department  of 
the  Local  Government  Board,  which  shall  be  a  Supreme  Rivers 
Authority,  dealing  with  matters  relating  to  rivers  and  their 
purification,  and  which,  when  appeal  is  made  to  them,  shall  have 
power  to  take  action  in  cases  where  the  Local  Authorities  have 
failed  to  do  so. 

A  fair  sewage  effluent  would  have  the  following  composition 
in  100,000  parts: 


Saline  and  free  ammonia  . 

Organic  ammonia 

Oxygen  absorbed  in  4  hours  at  8u°  F 

Oxidized  nitrogen 

Chlorine    ..... 

Suspended  matter 

Solids  in  solution 

(a)  Volatile 

(b)  Non-volatile 


1-50 

0-I2 
1-40 

i-oo 
lo-oo 

1-50 

86-15 
35-05 
51-10 


In  an  experimental  installation  at  Hanley,  the  sewage  being 
subjected  to  septic  tank  treatment  and  subsequent  filtration 
tlu-ough  a  streaming  filter  4^  feet  deep  formed  of  broken  saggars 
(a  waste  material  which  is  plentiful  in  the  pottery  towns),  and 
composed  as  to  the  lower  9  inches  of  particles  from  2J  to  i| 
inches  in  diameter,  and  as  to  the  upper  3  ft.  9  in.  of  particles 
h  to  I  inch  in  diameter,  Dr.  Reid  found  that  the  septic  tank 
effected  a  purification  of  64  per  cent,  and  62  per  cent,  in  the 
organic  ammonia  and  oxygen  absorbed  figures,  respectively,  as 
compared  with  the  crude  sewage,  whilst  as  regards  the  filter 
effluent  the  percentage  purification  was  97  per  cent,  and  94  per 
cent.,  the  amount  of  nitric  nitrogen  in  the  effluent  being  1-62 
parts  per  100.000. 

A  satisfactory  sewage  effluent  must  be  without  faecal  odour  and 
marked  deposit.  In  the  opinion  of  many,  the  organic  ammonia 
figure  is  the  best  criterion  of  a  satisfactory  effluent.     It  is  held 


158  HYGIENE   AND   PUBLIC   HEALTH 

by  some  authorities  that  this  figure  should  not  exceed  o-i  part 
per  100,000,  while  others  advocate  a  limit  of  015,  or  even  02. 
The  oxygen  absorbed  by  oxidizable  organic  matter  in  four  hours 
at  80°  F.  does  not  exceed  1-5  parts  per  100,000  in  good  effluents. 
The  chlorine  and  free  and  saline  ammonia  figures  are  unimportant, 
since  these  are  ultimate  products;  the  chlorine  in  the  effluent 
of  a  sewage  of  average  strength  is  about  10  parts  per  100,000. 
There  should  be  practically  no  solids  in  suspension;  the  Rivers 
Pollution  Commissioners'  standard  required  that  the  suspended 
matter  should  not  exceed  3  parts  of  dry  mineral  matter  per 
100,000,  nor  I  part  of  dry  organic  matter  per  100,000.  Above 
all,  the  final  effluent  must  not  be  liable  to  putrefaction  or 
secondary  decomposition. 

The  presence  of  oxidized  nitrogen  in  an  effluent  must  not  be 
regarded  as  a  sure  index  of  purity,  although  if  nitrates  are  found 
to  persist  in  an  inoffensive  effluent  for  a  few  days  after  its 
collection,  the  effluent  is  not  likely  to  become  offensive.  Nitrates 
are  a  measure  not  of  that  pollution  which  may  be  oxidized,  but 
of  that  which  has  been  oxidized,  and  their  presence  gives  no 
indication  of  what  remains  to  be  purified. 

No  general  standard  applicable  to  all  cases  is  possible  or 
desirable.  The  best  possible  results  must  always  be  aimed  at, 
having  due  regard  to  the  nature  of  the  sewage,  and  to  the 
conditions,  volume,  and  uses  of  the  stream  which  is  ultimately 
to  receive  it.  The  maximum  impurity  permissible  will  in  certain 
cases  be  very  slight  indeed,  while  in  others  a  greater  latitude 
may  be  conceded.  But  certainly  all  effluents  should  conform 
to  the  following  requirements:  they  should  contain  but  very 
httle  suspended  matter  (certainly  not  more  than  3  parts 
per  100,000) ;  they  should  possess  no  odour  of  sulphuretted 
hydrogen;  and  there  should  be  no  physical  evidence  of  putre- 
faction when  they  are  incubated  for  a  week  in  a  closed  vessel 
at  80°  F. 

The  Eighth  Report  of  the  Royal  Commission  on  Sewage  Dis- 
posal (1912)  suggests,  as  the  most  generally  satisfactory  test  for  a 
sewage  effluent,  discharged  into  non-tidal  waters,  the  determina- 
tion of  its  capacity  to  absorb  dissolved  oxygen,  the  test  to  be 
applied  to  the  effluent  with  all  its  suspended  solids,  and  not  to 
the  filtered  effluent  as  recommended  in  the  Fifth  Report  of  the 
Commission.  The  absorption  of  dissolved  oxygen  should  be 
allowed  to  proceed  for  five  days  at  a  uniform  temperature  of 


DISPOSAL   OF   REFUSE  159 

65°  F.,  and  in  this  period  the  absorption  of  dissolved  oxygen 
should  not  exceed  2  parts  by  weight  per  100,000  parts  of  effluent 
(=  14  c.c.  per  htre).  Further,  the  effluent  should  not  contain 
more  than  3  parts  of  suspended  solids  per  100,000. 

The  average  amount  of  oxygen  found  in  clean  fresh  water 
saturated  with  this  gas  is  i  part  per  100,000,  or  7  c.c.  per  litre. 
The  Commissioners  consider  that  if  a  river  water,  which  has 
received  sewage  effluent,  does  not  take  up  more  than  04  part 
of  oxygen  per  100,000  in  five  days  at  65°  F.,  the  water  will  be 
ordinarily  free  from  signs  of  poUution;  but  if  the  absorbed 
dissolved  oxygen  is  above  this  figure,  signs  of  pollution  will 
almost  certainly  be  apparent,  with  a  strong  probability  of  nuisance 
arising. 

The  effect  of  an  effluent  upon  a  stream  does  not  generally 
depend  upon  the  absolute  amount  of  organic  matter  contained 
in  it,  but  rather  on  the  nature  and  condition  of  the  organic 
matter.  The  important  point  to  ascertain  in  examining  an 
effluent  is  the  extent  to  which  the  original  organic  matter  has 
undergone  fermentation.  Thus,  an  effluent  which  is  non- 
putrescible  on  incubation  must  already  have  undergone  a  satis- 
factory amount  of  fermentation.  Not  only  will  it  remain  stable 
when  discharged  into  a  stream,  but  it  will  also  take  up  but  little 
dissolved  oxygen  from  the  water  into  which  it  is  discharged. 
An  effluent  which  does  not  take  up  dissolved  oxygen  from  the 
water  of  a  stream  more  rapidly  than  that  water  can  naturally 
re-aerate  itself  from  the  air,  will  be  unproductive  of  nuisance,  and 
will  not  injure  fish  life. 

As  regards  solid  suspended  matters  in  effluents  from  artificial 
filtration  processes,  on  an  average  two-thirds  of  them  are  volatile, 
i.e.,  organic,  and  one-third  are  mineral.  The  organic  solids  are 
practically  always  putrescible,  and  capable  of  taking  up  oxygen 
from  water  comparatively  rapidly.  So  long  as  such  solids  are 
kept  moving  in  oxygenated  water,  or  in  water  containing  nitrate 
in  solution,  they  will  cause  no  nuisance;  but,  if  allowed  to  accumu- 
late in  the  sluggish  reaches  of  a  stream,  they  will  ultimately  form 
a  black  and  putrid  mud. 

Nuisance  may  not  only  be  caused  in  a  stream  by  secondary 
fermentation  of  the  organic  matters  in  a  sewage  effiuent,  but  the 
effluent  may  cause  the  growth  in  the  stream  of  lowly  vegetable 
organisms,  which  often  give  rise  to  nuisance  and  difficulty. 
Even  the  best  effluents  contain  a  certain  amount  of  plant  food 


l60  HYGIENE   AND   PUBLIC   HEALTH 

in  solution,  and  therefore  tend  to  promote  vegetable  growths. 
In  the  case  of  a  stream  receiving  well-purified  and  nitrated 
effluents  these  growths  are  green,  from  the  presence  of  chlorophyll, 
and  are  unproductive  of  nuisance  until  they  become  detached  and 
decompose.  In  streams  receiving  imperfectly  oxidized  effluents, 
containing  much  sulphates,  grey  growths  of  the  sewage-fungus 
order  arise,  and  tend  to  choke  up  the  bed  of  the  stream,  at  the 
same  time  causing  an  offensive  nuisance  when  decomposition 
occurs. 

Intermittent  Downward  Filtration. 

When  sewage  percolates  through  porous  soil,  it  is  purified  to 
a  greater  or  less  extent.  This  purification  is  partly  due  to  the 
soil  acting  as  a  mechanical  filter,  separating  out  and  retain- 
ing the  suspended  matters  in  the  sewage;  but  greatly  more  to 
the  destruction  by  organisms  of  the  organic  matters  in  the 
sewage.  This  purification  is  chiefly  effected  by  the  bacterial 
organisms  which  exist  in  the  upper  layers  (extending  to  3  or  4 
feet  from  the  surface)  of  all  soils,  but  chiefly  in  those  rich  loamy 
soils  which  contain  much  organic  matter.  The  nitrifying 
organisms  feed  on  the  organic  matters  of  sewage,  causing  their 
oxidation.  They  require  air  and  oxygen  for  their  growth  and 
hfe,  which  are  supplied  to  them  when  the  soil  is  being  aerated 
during  its  periods  of  rest.  The  soil  or  the  sewage  should  also 
be  rich  in  hme  or  other  alkah;  for  the  nitric  and  nitrous  acids 
formed  by  the  nitrifying  organisms  must  be  able  to  combine 
with  bases,  or  the  nitrifying  action  ceases. 

A  very  large  volume  of  sewage  can  be  purified  on  a  small  area 
of  land,  if  the  soil  is  of  a  porous  and  rich  loamy  character.  Sandy 
soils  are  not  efficient  purifiers — at  any  rate  at  first.  Clay,  and 
other  retentive  soils,  must  be  well  broken  up  and  mixed  with 
ashes.  The  surface  of  the  land  must  be  levelled,  and  under- 
drained  with  porous  tile  drains,  laid  at  a  distance  of  about  10 
to  30  feet  apart,  according  to  the  nature  of  the  soil,  and  at  a 
depth  of  4  or  5  feet  from  the  smrface.  The  area  should  be  laid 
out  in  plots;  and  no  plot  should  receive  sewage  for  more  than 
six  hours,  so  that  it  may  have  eighteen  hours'  rest  out  of  the 
twenty-four;  to  this  end  the  screened,  filtered,  or  precipitated 
sewage  is  distributed  over  each  plot  of  ground  intermittently 
by  means  of  branching  carriers.  If  it  is  intended  to  apply  the 
sewage  of  more  than  1,000  people  to  an  acre,  the  sewage  should 
be  treated  chemically,  or  passed  through  a  septic  tank,  to  remove 


DISPOSAL   OF   REFUSE  l6l 

the  suspended  matters,  and  the  clarified  sewage  only  should  be 
appHed  to  the  land. 

When  crude  sewage  is  applied  in  large  volumes  to  a  small 
area  of  land,  the  pores  of  the  soil  become  clogged  with  the  slimy 
suspended  matters,  and  a  kind  of  coating  is  formed  over  the 
surface,  which  prevents  the  percolation  of  the  sewage  and  the 
penetration  of  air  into  the  interstices  of  the  soil.  When  the 
sewage  of  considerably  less  than  i,ooo  people  is  to  be  appUed 
per  acre,  the  screened  sewage  may  be  applied  in  its  crude  state; 
for  it  is  much  cheaper  to  allow  the  suspended  matters  to  reach  the 
soil  by  gravitation  in  the  liquid  sewage,  than  to  separate  them 
by  precipitation  and  then,  as  is  sometimes  necessary,  to  pump  the 
liquid  sludge  on  to  the  land.  It  is  generally  the  practice  to 
lay  out  the  filter  areas  in  ridges  and  furrows,  the  sewage  being 
allowed  to  flow  down  the  furrows,  whilst  vegetables  are  grown 
on  the  ridges.  The  roots  of  the  vegetables  assimilate  organic 
products,  and  thus  help  to  purify  the  sewage,  whilst  the  leaves 
and  stalks,  being  above  the  sewage,  are  not  contaminated  by 
floating  matters.  The  suspended  matters  deposited  from  the 
crude  sewage  in  the  furrows  must  be  dug  into  the  soil  from  time 
to  time,  before  they  have  time  to  form  an  impenetrable  coating. 

By  intermittent  downward  infiltration  through  specially  pre- 
pared filter-beds,  the  clarified  sewage  of  even  5,000  people  can 
be  appHed  to  each  acre  of  filter;  but  it  is  not  really  safe  to 
allow  less  than  i  acre  to  each  1,000  of  population  (20,000  to 
30,000  gallons  daily  of  dry  weather  sewage  flow),  when  the  inter- 
mittent downward  filtration  is  through  soil,  however  suitable 
the  soil  may  be.  Under  favourable  circumstances,  the  effluent 
water  issuing  from  the  drains  will  be  found  very  free  from  organic 
matter.  The  nitrogen  of  the  sewage  exists  in  the  effluent  water, 
but  in  the  innocuous  forms  of  ammonia,  nitrates,  and  nitrites. 
The  sewage,  therefore,  by  this  process  is  effectuall}^  purified; 
but  all  its  manurial  ingredients  are  wasted,  except  in  those  cases 
where  the  sale  of  vegetables,  grown  on  ridges,  covers  part  of  the 
cost  of  the  distribution.  But  the  area  of  land  being  so  limited, 
the  crops,  and  the  income  derived  from  their  sale,  must  necessarily 
be  very  small. 

Irrigation. 

In  the  words  of  the  Royal  Commission  on  Metropolitan  Sewage 
Discharge,  broad  irrigation  means  "  the  distribution  of  sewage 
over  a  large  surface  of  ordinary  agricultural  ground,  having  in 


i62  HYGIENE   AND   PUBLIC    HEALTH 

view  a  maximum  growth  of  vegetation  (consistently  with  due 
purification)  for  the  amount  of  sewage  supphed."  Filtration 
means  "  the  concentration  of  sewage  at  short  intervals,  on  an 
area  of  specially  chosen  porous  ground,  as  small  as  will  absorb 
and  cleanse  it ;  not  excluding  vegetation,  but  making  the  produce 
of  secondary  importance.  The  intermittency  of  application  is  a 
sine  qua  non  even  in  suitably  constituted  soils,  wherever  complete 
success  is  aimed  at." 

It  becomes  necessary  to  inquire  what  are  the  conditions  under 
which  the  crude  sewage  of  a  town  may  be  applied  to  land  by 
broad  irrigation.  Experience  has  taught  that  no  great  profit 
should  be  looked  for  from  a  sewage  farm.  Unfortunately  local 
authorities  have  found  great  difficulty  in  acquiring  sufficient 
land  at  a  low  rental  for  purifying  sewage. 

In  the  first  place,  the  land  chosen  should  be  so  situated  in 
relation  to  the  town  that  the  sewage  may  flow  to  it  by  gravita- 
tion; pumping  is  costly  and  greatly  reduces  any  profits  that 
may  arise.  The  rent  to  be  given  for  the  land  ought  not  to  exceed 
£2  los.  per  acre  (Bailey  Denton).  The  extent  of  land  that  should 
be  acquired  varies  under  different  circumstances;  on  an  average 
I  acre  to  every  100  to  200  persons  of  the  population  is  sufficient. 
The  best  kind  of  soil  is  a  friable  loam;  but  clayey,  gravelly, 
or  sandy  soils  are  all  capable  of  purifying  and  utihzing  sewage 
when  properly  managed.  "  Peat  and  stiff  clay  soils  are  generally 
unsuitable  for  the  purification  of  sewage  "  (Interim  Report  of 
the  Royal  Commission  on  Sewage  Disposal,  1901).  The  land 
must  be  levelled,  and,  unless  very  porous,  underdrained,  to  allow 
the  sewage  to  percolate  and  prevent  its  stagnation  on  the  surface. 
With  very  dense  clay  soils  filtration  is  impossible,  and  in  such 
cases  surface  flow  must  be  entirely  relied  upon.  This  is  capable 
of  giving  a  fairly  pure  effluent  if  the  sewage  has  been  freed  of 
suspended  matters  by  a  preliminary  precipitation,  and  if  the 
area  of  the  land  is  sufficient.  In  these  cases  undcrdrainage 
should  not  be  attempted,  as  in  dry  summer  weather  the  stiff' 
clay  soil  cracks,  and  the  sewage  may  pass  away  directly  through 
the  fissures  into  the  underdrains,  and  so  reach  the  watercourses 
unpurified.  The  main  carriers  for  the  distribution  of  the  sewage 
on  the  farm  should  be  masonry,  concrete,  or  stoneware  channels., 
which  can  be  easily  flushed  and  cleansed. 

Great  care  must  be  exercised  where  sewage  is  allowed  to  irrigate 
-land  of  a  clialky  nature,  or  where  a  top  layer  of  clayey  soil  of 


DISPOSAL   OF    REFUSE  163 

but  little  thickness  covers  a  thick  stratum  of  chalk.  In  ccitain 
chalk  formations,  what  are  known  as  "  swallow  holes  "  exist 
— that  is,  extensive  fissures  in  the  chalk  reaching  up  to  the  sur- 
face. In  such  cases  it  sometimes  may  happen  that  unpurified 
sewage  flowing  over  the  surface  may  disappear  into  one  of  these 
fissures  or  swallow  holes  and  pollute  the  underground  water, 
which  at  no  great  distance  away  may  be  pumped  out  of  a  deep 
well  in  the  chalk  to  supply  houses,  villages,  or  towns.  Such 
an  occurrence  is  believed  to  have  occurred  at  the  East  Riding 
Lunatic  Asylum,  near  Beverley,  Yorkshire.  The  top  layer  of 
clay  becomes  extensively  cracked  in  dry  summer  weather,  per- 
mitting unpurified  sewage  to  pass  through  to  the  chalk  beneath, 
where  it  was  conducted  by  fissures  to  the  deep  well,  about  half 
a  mile  distant,  which  supplied  Beverley  with  water.  As  the 
water  in  this  well  is  sometimes  depressed  b}^  pumping  to  the 
extent  of  17  feet,  the  area  of  the  circle  drained  by  the  well  must 
be  very  extensive.  In  the  immediate  neighbourhood,  a  stream 
much  polluted  by  the  sewage  of  a  village  on  its  banks  disappeared 
into  one  of  these  swallow  holes,  where  the  chalk  rises  up  into  the 
bed  of  the  stream. 

The  method  most  capable  of  general  application  for  applying 
the  sewage  from  the  main  carriers  to  the  surface  of  the  farm 
is  that  known  as  the  ridge  and  furrow  sj^stem.  The  surface  is 
laid  out  in  ridges — 30  to  60  feet  broad — running  parallel  to 
each  other,  and  at  right  angles  to  the  main  carrier,  with  a  slight 
fall  from  it.  Between  every  two  ridges  is  a  furrow  formed  by 
the  slope  (a  fall  of  several  inches)  of  the  two  ridges  towards  each 
other.  The  sewage  is  made  to  pass  down  a  grip  in  the  centre 
of  the  ridge,  and  thence  to  flow  over  the  sides  towards  the 
furrow.  When  the  central  grip  becomes  clogged  with  the  sus- 
pended matters  of  the  sewage,  it  should  be  filled  in,  and  a 
fresh  one  made  in  its  place.  The  underdrains  of  porous 
earthenware  should  be  laid  at  a  depth  of  about  5  feet  in  the 
soil,  and  from  20  to  100  feet  apart,  according  to  the  porosity 
of  the  soil. 

What  is  known  as  the  "  catch  water  system  "  of  irrigation 
can  be  adopted  where  the  areas  for  sewage  treatment  have 
sufficient  gradients.  By  this  method  a  series  of  furrows  or 
trenches  are  dug  in  lines  one  below  the  other.  The  sewage  is 
conducted  to  the  topmost  trench,  over  which  it  passes  to  find 
its  way  into  the  next  lower  trench,  and  so  downwards  to  the 


164  HYGIENE  AND  PUBLIC  HEALTH 

bottom  of  the  slope,  where  the  subsoil  effluent  is  collected  and 
carried  into  a  stream. 

The  best  crops  for  a  sewage  farm  are  Italian  rye  grass,  roots 
(mangold  wurzel),  and  cabbages.  Italian  rye  grass  absorbs 
a  large  volume  of  sewage,  and  bears  from  five  to  as  many  as 
seven  cuttings  in  the  year.  After  two  or  three  years,  the  plot 
of  rye  grass  should  be  ploughed  up,  and  the  land  sown  with 
cabbages  or  roots  (mangolds).  These  may  be  sewaged  when 
growing,  but  they  should  not  be  sewaged  when  they  arrive  at 
maturity.  They  help  to  exhaust  the  soil  of  the  sewage  products 
retained  in  it,  which  have  not  been  absorbed  by  the  rye  grass. 
Pulse,  cereals,  and  all  other  vegetables  should  not  be  sewaged 
when  in  growth,  except  in  times  of  great  drought.  The  land, 
when  fallow,  may  be  enriched  by  the  application  of  sewage; 
for  some  of  the  manurial  ingredients  of  sewage  are  doubtless 
retained  in  it,  ready  for  use  on  a  future  occasion.  Market 
gardening  may  be  undertaken,  and  made  very  profitable  on 
farms  where  the  area  of  land  is  more  than  sufficient  to  deal  with 
all  the  sewage ;  but,  where  this  is  not  the  case,  market  gardening 
does  not  answer,  because  the  area  so  cultivated  cannot  deal  with 
the  whole  volume  of  sewage. 

The  amount  of  capital  required  to  stock  and  work  a  sewage 
farm  is  very  great,  probably  five  times  the  amount  required  for 
an  ordinary  farm.  The  crops  that  have  to  be  taken  off  the 
land  are  enormous,  and  a  large  amount  of  labour  is  required  to 
keep  it  clean  and  free  from  weeds.  The  crops  of  Itahan  rye  grass, 
being  so  large,  may — and  often  do — exceed  the  demands  of  the 
local  markets.  If  not  sold  at  once,  the  grass  is  wasted;  for  it 
will  not  keep,  and  will  not  bear  long  carriage.  In  dry  summers 
it  may  be  made  into  hay,  and  at  other  times  it  may  be  converted 
into  ensilage.  It  has  been  found,  however,  that,  to  reap  the 
greatest  profits  from  a  sewage  farm,  the  produce  should  be 
converted  into  milk  and  meat.  In  other  words,  a  dairy  farm 
should  be  established,  and  stock  should  be  reared  and  fattened 
for  market.  The  idea  that  sewage-grown  vegetable  produce 
is  dropsical  and  prone  to  decompose  has  been  long  exploded. 
The  milk  and  meat,  also,  from  animals  fed  on  such  produce 
in  no  way  differs  from  milk  and  meat  produced  on  ordinary 
farms. 

From  experiments  extended  over  five  years  (1871-76),  the 
British  Association  Sewage  Committee  found  that  the  average 


DISPOSAL   OF    REFUSE  165 

amount  of  nitrogen  recovered  in  the  crops  of  a  sewage  farm  was 
3288  per  cent,  of  that  appHed  in  the  sewage.  About  ii  per 
cent,  of  the  nitrogen  in  the  sewage  escapes  in  the  effluent  water, 
ahnost  entirely  as  nitrates  and  nitrites,  whilst  a  portion  of  the 
unaccounted-for  nitrogen  is  stored  up  in,  and  enriches,  the  soil 
of  the  farm. 

The  amount  of  evaporation  of  water  from  the  surface  of  a 
sewage  farm  is  enormous.  The  above  committee  found  that, 
on  an  average  of  over  a  year's  observations,  only  473  per  cent, 
of  the  sewage  pumped  on  to  the  land  was  discharged  through 
the  deep  drains  as  effluent  water.  This  fact  must  be  reckoned 
with  on  making  analyses  of  effluent  water  from  sewage  farms, 
which  are  to  be  compared  with  samples  of  crude  sewage  flowing 
on  to  the  farm.  Although  the  evaporation  of  water  is  so  great, 
the  committee  found  that  there  was  no  loss  of  ammonia  from 
the  sewage  by  evaporation  in  its  passage  along  the  open  grips 
and  carriers  on  the  farm. 

One  of  the  great  drawbacks  to  the  utiHzation  of  sewage  by 
irrigation  is  the  fact  that  the  sewage  must  be  applied  to  the 
land  as  it  comes,  by  night  as  well  as  by  day;  on  Sundays  as 
well  as  on  week  days.  There  may  be  times  when  it  may  not 
be  desirable  to  apply  sewage  to  the  general  surface  of  the  farm, 
especially  during  wet  weather,  when  enormous  volumes  of  dilute 
sewage  arrive  at  the  farm.  This  difficulty  may  be  got  over  by 
laying  out  a  portion  of  the  farm  as  a  filter-bed  closely  drained. 
The  extent  of  this  filtration  area  should  be  sufficient  to  purify 
the  whole  of  the  sewage  when  not  required  on  the  general  surface 
of  the  farm.  The  land  may  be  left  fallow,  or  laid  out  in  ridges 
and  furrows  and  cropped.  When  the  sewage  is  much  diluted 
with  storm  water,  it  may,  in  other  cases,  be  carried  over  a  specially 
prepared  filtering  area  planted  with  osier  beds,  or  over  meadow 
lands,  before  being  discharged  into  a  stream.  It  would  be  of 
great  advantage  if  storm  and  subsoil  waters  could  always  be 
excluded  from  the  sewers;  the  problem  of  satisfactory  disposal 
of  the  sewage  would  be  thereby  greatly  facilitated. 

During  the  most  severe  frosts  irrigation  may  continue  uninter- 
ruptedly. A  coating  of  ice  is  formed  over  the  surface  of  the 
farm,  but  the  sewage,  which  always  has  a  temperature  well  above 
the  freezing-point,  flows  underneath  this  coating  and  sinks  into 
the  soil,  which  remains  unfrozen  and  open.  As  the  weather 
moderates,  the  sewage  rapidly  melts  the  ice  above  it.     Even 


l66  HYGIENE    AND    PUBLIC   HEALTH 

in  America,  where  the  frosts  are  most  intense,  no  trouble  has 
arisen  from  this  cause  on  any  of  the  sewage  farms. 

Are  sewage  farms  productive  of  nuisance  and  injury  to  health  ? 
There  can  be  no  doubt  that  badly  managed  farms— where  more 
sewage  is  applied  than  the  land  can  absorb  and  cleanse,  or  where, 
from  the  sewage  being  appHed  too  continuously,  the  surface 
becomes  sodden,  and  ponded  sewage  stagnates  on  it — may  be 
a  nuisance.  When  properly  conducted,  and  the  sewage  is 
distributed  over  the  land  in  as  fresh  a  state  as  possible,  and  not 
after  prolonged  sojourn  in  a  lengthy  main  or  outfall  sewer, 
sewage  irrigation  is  not  found  to  be  productive  of  any  nuisance. 

That  sewage  farming  is  no  more  unhealthy  than  ordinary 
farming  is  shown  from  the  returns  of  the  nine  sewage  farms  which 
were  in  competition  for  the  Royal  Agricultural  Society's  prizes. 
The  rate  of  mortality  amongst  the  labourers  and  their  families, 
on  an  average  of  the  number  of  years  these  farms  had  been 
in  operation,  did  not  exceed  3  per  1,000  per  annum.  No  facts, 
either,  have  ever  been  brought  forward  in  favour  of  the  view 
that  entozoic  diseases  are  spread  by  the  agency  of  sewage  farms. 
It  is  probable  that  alkaline  sewage  destroys  organisms  Hke  the 
ova  of  tapeworms,  whose  natural  habitat  is  the  acid  secretion 
of  the  human  intestines.  If  so,  they  are  destroyed  before  they 
arrive  at  the  farm.  On  one  farm,  too,  it  was  found  that  there 
was  a  remarkable  absence  of  those  molluscan  and  insect  forms 
of  life  which  frequently  play  the  part  of  intermediary  bearers 
to  entozoal  larvae,  and  without  which  the  cycle  of  their  existence 
cannot  be  completed.  Even  where  cattle  have  been  allowed 
to  feed  upon  land  to  which  sewage  is  being  appHed,  it  has  not 
been  found  that  they  are  in  any  way  affected  with  parasitic 
diseases. 

Generally  speaking,  land  is  becoming  too  valuable  to  be  put 
to  purposes  of  sewage  purification,  hence  the  modern  endeavour 
to  reproduce  all  the  most  favourable  conditions  of  land  and  to 
concentrate  them  in  a  small  area  known  as  a  bacterial  bed; 
but  where  land,  suitable  in  nature  and  quantity,  can  be  procured, 
equally  good  results  are  obtainable. 


CHAPTER  III 

AIR  AND  VENTILATION 

Pure   atmospheric    air,    freed   from   aqueous   vapour,    has   the 
following  volumetric  composition: — 

Oxygen           .  .             .             .             .  2094 

Nitrogen         .  .             .             .             .  7809 

Argon              .  .             .             .             .  094 

Carbonic  acid  ....  0-03 

100-00 


The  amount  of  aqueous  vapour  present  in  air  is  variable,  the  average 
in  this  country  being  1-4  per  cent. 

Traces  of  organic  matter,  ozone,  mineral  salts,  ammonia,  nitric  acid, 
neon,  helium,  krypton,  xenon,  hydrogen,  and  carburetted  hydrogen  are 
found  in  air;  and  in  towns  sulphurous  acid  and  sulphuretted  hydrogen. 

This  composition  is,  as  regards  the  four  gases  which  compose 
almost  the  entire  bulk  of  ordinary  air,  remarkably  uniform 
in  every  part  of  the  world.  Even  in  the  midst  of  large  cities, 
where  the  atmosphere  is  being  polluted  in  many  ways,  the  air 
of  open  spaces  differs  but  very  slightly  in  the  proportion  of  its 
constituent  gases  from  the  air  on  the  open  plains,  mountains, 
or  seas,which  is  far  removed  from  such  sources  of  contamination. 
This  is  not  to  be  wondered  at  when  the  immense  power  and 
universality  of  the  forces  which  promote  purification  of  the 
atmosphere  are  considered.  Such  are:— The  wind,  which  dilutes 
and  sweeps  away  impurities,  bringing  pure  air  in  their  place; 
the  rain,  which  washes  the  air,  carrying  down  in  its  fall  dis- 
solved gases  and  suspended  impurities;  the  chemical  effects  of 
the  oxygen  and  ozone  in  the  air  on  the  oxidizable  matters  in  it ; 
and,  lastly,  the  power  possessed  by  the  green  parts  of  plants, 
in  sunHght,  of  absorbing  carbonic  acid,  fixing  the  carbon,  and 
setting  free  the  oxygen.     The  latter  process  is,  however,  reversed 

167 


l68  HYGIENE   AND    PUBLIC    HEALTH 

during  the  hours  of  night,  COg  being  evolved;  but  the  balance 
is  decidedly  in  favour  of  purification. 

Ozone,  which  is  oxygen  in  an  allotropic  and  highly  active 
condition,  is  generally  absent  from  town  air,  even  in  open  squares 
and  parks. 

Confining  our  attention  for  the  present  to  the  outer  air — the 
air  outside  buildings — it  has  been  found  in  large  cities  that 
when  the  atmosphere  is  stagnant,  and  no  wind  is  blowing, 
especially  during  fogs,  the  air  of  open  spaces  may  contain  only 
some  20 -So  per  cent,  of  oxygen,  or  even  less,  and  the  carbonic 
acid  may  exceed  o-o6  per  cent.,  with  a  considerable  increase 
likewise  in  organic  matters.  Such  observations  have  been  made 
in  London  and  Manchester.  In  the  narrow  closed  courts  or 
streets,  surrounded  by  high  buildings,  which  constitute  so  large 
a  portion  of  the  densely  populated  parts  of  these  cities,  the  air 
has  been  found  considerably  more  impure  than  the  samples 
above  given,  which  were  taken  from  open  spaces.  The  air  of 
such  places  is  stagnant  and  confined,  as  in  a  well;  there  is  no 
circulation  to  effect  a  proper  renewal  of  fresh  air  and  dispersion 
of  accumulated  impurities,  and  the  sun  rarely  penetrates.  Yet 
such  is  the  only  air  supply  attainable  in  thousands  of  the 
dwellings  of  the  poorer  classes. 

We  thus  see  that  although  in  towns  much  may  be  done  by 
constructing  wide  and  airy  streets,  by  preventing  the  undue 
aggregation  of  dwellings  and  their  back  to  back  construction, 
and  by  suitable  restrictions  as  to  their  height,  to  provide  for 
proper  ventilation  and  purification  of  the  atmosphere,  yet  its 
purity  is  liable  to  variations,  which  do  not  occur  in  the  air  of 
the  open  country.  These  variations  may  be  only  very  slight 
in  amount,  but  they  are  not  unimportant.  Their  bearing  on 
the  health  and  vitality  of  the  populations  exposed  to  their 
influence  is  probably  considerable. 

Amongst  suspended  matters  usually  present  in  the  air,  to  a 
greater  or  less  extent,  are  minute  particles  of  mineral  matter 
(including  common  salt,  especially  near  the  sea),  soot,  dust  of 
various  kinds — in  towns  consisting  largely  of  organic  matters 
from  horse  droppings — textile  fibres,  vegetable  debris,  pollen 
of  grasses  and  flowers  in  the  early  summer,  the  spores  of  various 
fungi  and  moulds,  diatoms,  bacteria  and  their  spores,  monads 
and  amoebiform  organisms — dead  and  living.  The  purest  air, 
such   as  exists  at  considerable  elevations  on   mountains  and 


AIR    AND   VENTILATION  169 

over  the  sea,  contains  but  very  little  suspended  matter.  In 
towns,  especially  manufacturing  towns,  the  air  is  often  loaded 
with  soot  and  dust  of  mineral  origin.  The  dust  in  the  atmo- 
sphere provides  innumerable  nuclei  for  the  condensation  of 
moisture  or  water  vapour. 

In  towns,  the  amount  of  organic  and  mineral  dust  in  the  air 
will  depend  greatty  on  the  efficiency  of  the  scavenging  and 
watering  of  the  streets.  The  wind  raises  minute  particles  from 
the  surface  of  the  ground,  and  carries  them  often  great  distances 
before  the}^  are  deposited.  In  this  way  infectious  particles  from 
domestic  dust  heaps  and  dried  excreta  may  be  caught  up  and 
carried  into  the  air. 

Air  is  vitiated  by  respiration  of  men  and  animals  ;  by  com- 
hustion  of  coal,  gas,  oil,  etc.  ;  by  fermentation  and  putrefaction 
of  animal  and  vegetable  organic  matters  ;  by  various  trade  and 
manufacturing  processes. 

Vitiation  by  Respiration. 

An  adult  individual  at  rest  breathes  at  the  rate  of  about 
seventeen  respirations  a  minute.  At  each  respiration  about 
500  c.c.  (30-5  cubic  inches)  of  air  pass  in  and  out  of  his  lungs. 
The  air  in  the  lungs  loses  4  per  cent,  of  oxygen,  which  is  absorbed 
by  the  blood  in  the  pulmonary  capillaries,  and  gains  carbonic 
acid  from  the  venous  blood  to  the  extent  of  3-5  to  4  per  cent. 
The  nitrogen  remains  unchanged.  In  addition,  the  expired  air 
is  raised  in  temperature  to  nearly  that  of  the  blood,  98-4°  F.; 
it  contains  5  per  cent,  of  aqueous  vapour,  and  a  larger  pro- 
portion of  putrefiable  organic  matters  than  the  air  which  it 
inspired. 

The  amount  of  carbonic  acid  which  is  given  off  by  an  adult 
male  person  at  rest  can  be  calculated  from  the  above  figures, 
and  will  be  found  to  be  072  cubic  foot  in  one  hour.  From 
actual  experiment  it  has  been  determined  that  an  average  adult 
gives  off  0-9  of  a  cubic  foot  of  CO.,  during  gentle  exertion,  and 
possibly  as  much  as  i-8  during  hard  work.  The  adult  female 
gives  off  about  one-fifth  less  of  each  of  these  quantities  under 
similar  circumstances,  and  an  infant  is  said  to  give  off  about 
05  cubic  foot  of  CO.,  per  hour.     In  a  mixed  assembly  at  rest, 

17  X  30x^10^    ^^^  ^^^^  breathed  per  hour. 

1728      ^  ■^ 
4  per  cent,  of  171=0-72  cub.  foot  per  hour  of  COg. 


170  HYGIENE   AND   PUBLIC    HEALTH 

including  male  and  female  adults  and  children,  the  CO2  given 
off  per  head  is  therefore  taken  as  o-6  of  a  cubic  foot. 

The  repeated  inhalation  of  air  fouled  by  human  beings  tends 
to  the  production  of  a  lowered  state  of  health  and  promotes  the 
onset  of  disease. 

Recent  experiments  have  demonstrated  that  the  physical 
changes  in  impure  air  are  mainly  responsible  for  the  usual 
symptoms  complained  of  in  overcrowded  rooms. 

These  experiments  included  a  number  of  tests  made  in  a 
specially  constructed  glass  chamber  in  which  the  physical  and 
chemical  qualities  of  the  air  could  be  rigorously  controlled.  It 
was  found  that  with  a  respiratory  impurity  of  carbonic  acid 
exceeding  any  recorded  up  to  that  time  as  having  been  found 
in  the  air  of  a  crowded  room — e.g.,  from  i-o  to  1-5  or  even 
17  per  cent. — no  injurious  property  of  the  air  could  be  demon- 
strated so  long  as  the  temperature  and  humidity  were  kept  low; 
and  that  under  these  circumstances  the  absence  of  any  dis- 
turbance was  so  complete  that  the  power  of  co-ordination 
remained  intact — as  was  proved  by  the  ease  and  normal  manner 
in  which  certain  arithmetical  calculations  given  by  way  of  test 
were  carried  out.  Parallel  results  have  been  obtained  in  the 
case  of  schoolrooms  crowded  with  children,  but  in  which  the 
temperature  was  kept  low. 

On  the  other  hand,  as  soon  as  the  temperature  and  humidity 
were  increased  to  beyond  certain  hmits,  there  appeared,  both  in 
normal  and  in  diseased  persons  who  were  submitted  to  experi- 
ment, the  usual  symptoms  that  occur  when  people  are  crowded 
together  in  one  room — i.e.,  feehngs  of  drowsiness  and  headache, 
oppression,  lassitude,  giddiness,  nausea,  etc.  These  symptoms, 
however,  could  be  relieved  at  once  simply  by  reducing  the 
temperature  and  humidity  of  the  air  to  normal,  and  they  may 
be  attributable  to  heat  retention. 

Increase  of  Carbon-dioxide  Gas. — In  the  air  of  an  inhabited 
room  the  amount  of  CO2  is  always  increased,  as  compared  with 
pure  air;  and  this  increase  is  directly  proportional  to  the  number 
of  persons  present,  and  inversely  proportional  to  the  volume 
of  fresh  air  introduced  by  ventilation.  But  the  increase  of 
CO2,  even  in  crowded  and  badly  ventilated  rooms,  is  compara- 
tively speaking  a  small  matter.  The  amount  of  CO.,  by  volume 
in  pure  air  being  from  3  to  4  parts  per  10,000,  in  inhabited 
rooms,   the  proportion  of  CO2,  even  where    there  is  excessive 


AIR    AND   VENTILATION  I7I 

crowding  and  very  defective  ventilation,  as  in  some  elementary 
schools,  seldom  rises  above  50  volumes  per  10,000,  and  it  requires 
about  six  times  as  much  (300  volumes  per  10,000)  to  produce 
an  immediately  perceptible  effect  on  the  respiration,  as  shown 
by  increased  depth  and  frequency  of  breathing  (Haldane)  ; 
whilst  no  poisonous  effects  appear  to  be  produced  until  the 
proportion  of  CO.,  rises  to  500  volumes  per  10,000,  or  10  times 
the  amount  ever  hkely  to  be  found  in  inhabited  rooms.  There 
is  always  about  6  per  cent,  of  CO2  in  the  residual  air  of  the  pul- 
monary alveoli  (Haldane  and  Priestley).  An  increase  of  COg 
in  the  respired  air  stimulates  the  respiratory  centre  to  induce 
increased  pulmonary  action,  so  that  the  percentage  of  COg  in 
the  alveolar  air  remains  constant.  The  alteration  in  the  breath- 
ing induced  by  respiring  air  containing  50  volumes  of  CO2  per 
10,000  is  quite  inappreciable.  A  slight  muscular  exertion,  such 
as  that  of  walking  at  the  rate  of  3  miles  an  hour,  would  pro- 
duce 30  times  as  nmch  effect  on  the  breathing.  From  these 
facts  it  may  be  inferred  that  the  increased  CO.,  in  the  air  of 
inhabited  rooms  is  not  of  itself  productive  of  injury  to  health. 

Diminution  of  Oxygen. — The  diminution  of  oxygen  in  air 
vitiated  b\^  respiration  has  been  the  subject  of  experiment,  but 
in  no  case  has  the  reduction  been  found  to  be  more  than  trifling. 
The  normal  amount  of  oxygen  in  pure  air  being  20-94  per  cent, 
by  volume,  instances  have  been  recorded  where  the  oxygen  has 
been  reduced  to  2065;  but  it  can  hardly  be  supposed  that  such 
a  reduction  can  exert  any  influence  on  health,  having  regard 
to  the  fact  that  many  mountain  climates  are  notoriously  healthy 
at  altitudes  where  the  diminution  of  atmospheric  pressure  cor- 
responds with  a  very  much  greater  reduction  in  the  percentage 
of  oxygen. 

Ozone. — Formerly  considerable  importance  was  attributed  to 
the  alleged  absence  of  ozone  from  the  air  of  inhabited  places. 
But  owing  to  the  unreliability  of  the  methods  for  ascertaining 
the  presence  of  this  gas,  doubt  has  risen  as  to  whether  this 
supposed  allotropic  form  of  oxygen  exists  in  the  general  atmo- 
sphere at  all,  and  whether  the  supposed  characteristics  of  ozone 
are  not  really  due  to  the  presence  of  nitrous  acid. 

Organic  Matter. — For  man}'  j^ears  it  was  believed  that  the 
injurious  effects  due  to  the  breathing  of  air  vitiated  by  human 
respiration  were  attributable  to  organic  matters  contained  in 
expired  air.     It  was  supposed  that  these  organic  matters  were 


172  HYGIENE   AND   PUBLIC   HEALTH 

partly  suspended  in  the  air,  consisting  of  small  particles  of  epi- 
thelium and  fatty  matters  from  the  mouth,  and  in  part  were 
in  the  form  of  an  organic  vapour  from  the  lungs  and  air-passages, 
which  was  held  to  be  nitrogenous  in  character  and  poisonous 
when  rebreathed.  The  experiments,  however,  of  Berger, 
Weir  Mitchell,  and  Billings  in  the  United  States,  and  of  Haldane 
and  Lorrain  Smith  in  this  country,  tend  to  show  that  there  is 
no  volatile  organic  poison  in  expired  air;  whilst  there  is  no 
definite  proof  that  the  tests  for  the  presence  of  organic  matter 
in  air  vitiated  by  respiration  are  any  indications  that  the  source 
of  such  matters  is  the  air  expelled  from  the  lungs.  The  reducing 
action  of  vitiated  air  upon  permanganate  of  potash  may  be 
due  to  other  constituents  of  such  air  than  organic  matters;  and 
the  fact  that  the  washings  of  such  air  with  distilled  water  yield, 
on  distillation,  ammonia  and  albuminoid  ammonia  in  excess 
of  that  present  in  pure  air,  does  not  necessarily  mean  that  the 
organic  matters,  of  which  these  ammonias  may  be  taken  as 
evidence,  are  invariably  derived  from  the  lungs.  They  may, 
in  fact,  be  due  to  volatile  products  given  off  from  the  teeth  and 
gums,  from  dirty  skins,  and  from  excretions  adhering  to  foul 
clothing.  More  exact  research  is  required  to  ascertain  the 
organic  constituents  (if  any)  of  expired  air,  and  to  differentiate 
them  from  the  volatile  products  of  decomposition  arising  from 
the  general  surface  and  other  parts  of  the  body. 

Personal  Emanations. — These  emanations  are  undoubtedly 
very  largely  responsible  for  the  unpleasant  odours  which  are 
perceptible  on  passing  from  the  outer  air  into  a  crowded,  unven- 
tilated  room,  more  particularly  when  the  occupants  are  persons 
of  imcleanly  habit.  No  sufficient  experiments  have  been  made, 
nor  are  there  perhaps  any  satisfactory  tests  known  which  could 
determine  the  nature  and  quantity  of  the  volatile  matters  to 
which  these  odours  are  due.  It  is  possible  that  the  deleterious 
action  of  air  vitiated  by  the  presence  of  human  beings  is  to 
some  extent  due  to  the  presence  of  these  odoriferous  volatile 
substances,  minute  in  amount  though  they  be.  The  long  con- 
tinued action  of  such  substances  on  the  olfactory  nerves  ma}' 
ultimately  induce  through  the  central  nervous  system  alterations 
in  respiration,  circulation  and  nutrition,  which  are  inconsistent 
with  the  maintenance  of  good  health. 

Heat  and  Moisture. — It  is  probable  that  the  heightened  tem- 
perature and  the  larger  amount  of  watery  vapour  present  in 


AIR   AND    VENTILATION  I73 

the  air  of  places  much  vitiated  by  the  presence  of  human  beings 
are  auxihary  factors  of  some  importance  in  producing  loss  of 
health.  The  debihtating  effects  produced  by  respiring  impure 
air  are  undoubtedly  augmented  when  such  air  is  much  raised 
in  temperature,  and  the  tendency  to  an  increased  output  of 
foul-smelhng  volatile  products  from  the  bodies  of  the  occupants 
of  a  room  is  materially  increased  by  a  high  temperature  and  an 
atmosphere  approaching  saturation  from  the  presence  of  mois- 
ture given  off  in  the  breath.  Unless  the  vitiation,  however, 
is  extreme,  it  is  but  seldom  that  the  temperature  of  the  air  or 
its  relative  humidity  are  sufficiently  raised  by  the  presence  of 
the  occupants  of  a  room  to  exert  any  noticeable  effects,  apart 
from  the  much  greater  effects  produced  in  the  same  direction  by 
the  combustion  of  fires  and  gas. 

Micro-organisms. — It  is  now  known  that  during  ordinary  quiet 
breathing  micro-organisms  are  not  given  off  from  the  air-pas- 
sages to  the  expired  air;  but  that  the  respiratory  efforts  associated 
with  laboured  respiration,  such  as  coughing,  sneezing,  and  loud 
talking,  are  characterized  by  the  spraying  of  microbes  present 
on  the  mucous  membranes  of  the  air-passages  into  the  air.  Most 
of  the  microbes  so  given  off  are  harmless  and  incapable  of  affect- 
ing the  health  of  those  who  breathe  such  air;  but  at  times  the 
infective  organisms  of  nasal  and  laryngeal  catarrhs,  of  influenza, 
diphtheria,  tuberculosis,  and  other  diseases,  are  thus  ejected  from 
the  air-passages,  and  may  be  the  means  of  propagating  these 
diseases.  Apart,  however,  from  the  occasional  presence  of 
definite  pathogenic  bacteria,  the  number  of  harmless  organisms 
in  the  air  we  breathe  does  not  appear  to  be  very  material.  A 
small  number  of  germs  per  htre  of  air  is  more  an  indication  of 
cleanliness  of  the  apartment  and  the  absence  of  dust,  than  of 
efficient  ventilation  and  the  avoidance  of  respiratory  impurity. 

The  number  of  microbes  present  in  air  vitiated  by  respiration 
seems  to  bear  no  very  definite  relation  to  the  amount  of  CO2 
gas  present.  This  is  not  to  be  wondered  at  when  we  know  that 
the  greatest  numbers  of  microbes  are  found  in  the  air  which 
contains  the  largest  amount  of  dust,  and  that  the  air  of  inhabited 
places  may  be  stagnant  and  therefore  comparatively  free  from 
dust,  although  much  polluted  by  respiration.  It  appears  also 
that  the  microbes  and  dust  particles  in  the  air  we  breathe  do 
not  as  a  rule  reach  the  lungs,  but  adhere  to  the  moist  membranes 
lining  the  mouth,  nose,  and  throat,  and  are  got  rid  of  by  the 


174  HYGIENE   AND   PUBLIC   HEALTH 

mucous  excretions  of  these  membranes.  The  air  reaching  the 
lungs  is  consequently,  as  a  rule,  sterile;  and  the  expired  air  in 
gentle  breathing  is  also  devoid  of  organisms.  It  is  probable 
that  the  infective  organisms  present  occasionally  in  the  air  are 
absorbed  into  the  system,  after  being  deposited  on  the  mucous 
surfaces  of  the  nose,  tonsils,  or  palate,  and  only  occasionally 
reach  the  air  cells  or  bronchi  of  the  lungs. 

On  the  whole,  then,  it  would  appear  that  there  is  some  con- 
stituent of  air  vitiated  by  human  respiration  and  transpiration, 
which  is  responsible  for  the  injurious  action  of  such  air  upon 
health,  but  that  this  constituent  has  not  yet  been  certainly 
identified.  Whether  this  unknown  substance  is  present  in  the 
air  from  the  lungs,  or  whether  it  is  given  off  from  other  parts 
of  the  body,  is  uncertain.  It  hardly  seems  probable  that  excess 
of  CO.^,  deficiency  of  oxygen,  absence  of  ozone,  a  raised  tem- 
perature, excess  of  moisture,  or  the  presence  in  the  air  of  non- 
pathogenic micro-organisms  from  the  air-passages,  taken  either 
singly  or  in  combination,  would  be  able  to  give  rise  to  those  far- 
reaching  effects  that  the  continued  respiration  of  foul  atmospheres 
is  known  to  produce.  It  may,  however,  be  the  fact  that  whilst 
nothing  of  any  importance  is  given  off  to  the  air  by  human 
respiration  and  transpiration,  yet  the  air  by  such  means  is 
deprived  of  some  vital  element,  with  which  we  are  unacquainted, 
and  without  which  the  highest  state  of  bodily  health  and  efficiency 
cannot  be  maintained. 

The  purity  of  the  air  in  dwelling  rooms  depends  upon  the 
amount  of  cubic  space  for  each  individual  and  the  facilities 
afforded  for  the  entrance  of  fresh  and  the  exit  of  foul  air.  Where 
these  points  are  properly  attended  to,  the  air,  although  rather 
more  impure  than  the  external  atmosphere,  will  not  be  pro- 
ductive of  injury  to  health.  In  those  extreme  cases  where  many 
people  are  crowded  together  and  the  ventilation  is  totally  in- 
adequate, the  air  often  becomes  sufficiently  impure  to  cause 
headache,  lassitude,  nausea,  and  fainting.  In  a  schoolroom 
crowded  with  seventy  girls  Pettenkofer  found  the  carbonic  acid 
to  exist  in  the  air  to  the  extent  of  0723  per  cent.,  or  about 
twenty  times  the  amount  normally  present  in  air;  whilst  the 
organic  matter,  measured  as  albuminoid  ammonia  (usually 
present  in  pure  air  to  the  extent  of  008  milligramme  per  cubic 
meter),  has  been  found  in  the  ward  of  a  hospital  to  reach 
1-3  milligrammes  per  cubic  metre. 


AIR   AND   VENTILATION  1 75 

The  above  figures  represent  in  eaeh  case  excessively  foul 
atmospheres;  all  intermediate  conditions  of  air,  varying  accord- 
ing to  circumstance,  may  be  found  in  the  different  kinds  of 
inhabited  rooms  and  dwellings.  The  long-continued  breathing 
of  even  nmch  less  vitiated  air  than  the  above  sample  is,  probably, 
one  of  the  causes  of  rickets  in  children,  and  tends  to  produce 
a  lowered  state  of  vitality,  characterized  by  anaemia,  dyspepsia, 
and  lassitude,  in  older  people.  People  in  this  lowered  condition 
of  health,  which  is  very  common  amongst  those  who  spend  the 
greater  portion  of  every  day  indoors,  in  offices,  schools,  work- 
rooms and  factories,  offer  much  less  resistance  to  attacks  of 
acute  disease  than  do  people  who  live  out-of-door  lives;  and 
they  are  greatly  more  subject  to  all  chronic  and  wasting  diseases. 
Dr.  Ogle's  researches  have  shown  that,  of  all  the  industrial 
classes,  those  which  are  the  healthiest  and  have  the  lowest 
death  rates  are  the  gardeners,  farmers,  agricultural  labourers, 
and  fishermen — those,  namely,  whose  occupations  are  carried 
on  in  the  open  air.  The  death  rate  from  phthisis  in  these  classes 
is  only  half  that  of  the  male  community  generally,  and  they 
enjoy  about  the  same  amount  of  freedom  from  diseases  of  the 
respiratory  organs.  Differences  in  food  or  housing  accommo- 
dation cannot  account  for  the  comparative  freedom  of  these 
classes  from  pulmonary  disease. 

The  causal  relation  subsisting  between  foul  air,  produced  by 
overcrowding  and  insufficient  ventilation,  and  phthisis  is  now 
generally  recognized.  The  most  convincing  proofs  of  such  a 
relation  are  to  be  found  in  the  comparative  immunity  enjoyed 
by  soldiers,  sailors,  and  prisoners  at  the  present  time  from  this 
disease.  Formerly,  owing  to  the  very  hmited  amount  of  cubic 
space  allotted  per  head,  and  the  disregard  paid  to  ventilation, 
phthisis  was  considerably  more  prevalent  among  soldiers.  Royal 
Navy  sailors  and  marines,  and  prisoners  in  His  Majesty's  gaols 
than  amongst  the  males  of  the  same  age  in  the  classes  from 
which  they  were  derived.  At  the  present  time,  other  conditions, 
such  as  food,  exercise,  etc.,  remaining  much  the  same,  but  more 
air-space  and  better  ventilation  having  since  been  provided, 
the  death  rate  from  phthisis  is  considerably  less  amongst  these 
servants  and  prisoners  of  the  State  than  amongst  the  civil 
population. 

The  theory  of  the  contagiousness  of  phthisis  has  received  the 
strongest   confirmation    from    the    discovery   by    Koch    of    the 


176  HYGIENE   AND   PUBLIC   HEALTH 

tubercle  bacillus,  an  organism  invariably  present  in  tubercular 
deposits,  but  not  found  in  any  other  disease.  The  tubercle 
bacillus  is  present  in  the  sputa,  and  in  the  droplets  of  saliva 
ejected  by  chronic  consumptives  during  coughing,  and  may  be 
thus  transferred  through  the  air  to  the  lungs  of  the  healthy, 
under  conditions  of  too  close  crowding  and  failure  to  observe 
other  necessary  precautions. 

The  excessive  incidence  of  disease  on  the  inmates  of  back-to- 
back  houses,  in  which  there  can  be  no  through  ventilation  and 
circulation  of  air,  has  been  well  established. 

Acute  diseases  of  the  air-passages,  especially  catarrhs,  bron- 
chitis, and  pneumonia,  are  very  prevalent  among  those  who 
live  in  heated,  overcrowded  rooms. 

The  zymotic  diseases  generally  are  more  prevalent  amongst 
overcrowded  populations  than  amongst  those  who  are  better 
lodged;  but  this  may  be  accounted  for  by  the  ease  with  which 
contagion  can  pass  from  the  sick  to  the  healthy;  for  air  vitiated 
by  the  ordinary  products  of  respiration  of  a  healthy  person  may 
induce  illness,  but  cannot  be  productive  of  a  specific  disease. 

There  is,  however,  evidence  that  insufficient  air-space  and 
defective  ventilation  of  school  dormitories  and  classrooms  tend 
to  produce  inflammatory  conditions  of  the  throat  (follicular  and 
ulcerative  tonsillitis),  which  in  some  instances,  as  the  outbreak 
progresses,  may  be  indirectly  responsible  for  attacks  of  true 
diphtheria.  The  defective  ventilation  induces  the  unhealthy 
throat  conditions;  and  the  subsequent  appearance  of  diphtheria 
may,  as  Thorne  supposed,  be  due  to  progressive  development 
in  type  of  the  throat  organisms,  or,  as  is  more  probable,  it 
may  merely  be  due  to  the  accidental  introduction  of  the  true 
Bacillus  diphthericB,  which  at  once  assumes  virulence  under  the 
defective  sanitary  conditions  prevailing. 

In  the  air  of  ill-ventilated  sick-rooms  and  hospital  wards  the 
debris  of  dried  epithelial  scales  and  pus  cells  may  often  be  found 
floating.  These  matters  are  especially  frequent  in  wards  where 
many  of  the  patients  have  purulent  discharges  from  suppurating 
wounds  or  copious  expectoration  from  the  lungs,  and  are  usually 
accompanied  by  an  abundance  of  spores  of  fungi  and  bacteria, 
and  large  excess  of  organic  matters  generally  in  the  air.  In 
many  persons  the  breathing  of  such  polluted  air  produces  an 
immediate  effect  on  the  throat  and  tonsils,  passing  sometimes  into 
acute  tonsiUitis  or  hospital  sore  throat.     Its  eftect  in  increasing 


AIR    AND    VENTILATION  I77 

the  severity  of,  and  in  retarding  recovery  and  convalescence 
from  acute  disease,  is  now  generally  recognized.  Patients 
suffering  from  erysipelas,  ophthalmia,  pyaemia,  septicaemia, 
and  hospital  gangrene,  are  undoubtedly  infectious  to  those  who 
have  open  wounds.  The  contagious  particles  (pyogenic  micro- 
organisms of  various  kinds) — contained  in  dried  epithelial  scales 
and  pus  cells — may  be  transferred  through  the  air  from  patient 
to  patient;  and  often  no  measure  short  of  emptying  the  ward 
appears  to  be  of  any  avail  to  stop  an  epidemic  once  begun. 
In  times  not  very  far  distant,  these  diseases  were,  in  the 
surgical  wards  of  many  hospitals  and  infirmaries,  almost  con- 
stantly present.  Freer  ventilation,  improved  sanitary  arrange- 
ments, and  the  aseptic  treatment  of  wounds  and  injuries, 
have  almost  eradicated  such  calamities  from  modern  hospital 
practice. 

It  is  possible  that  parasitic  skin  diseases  may  spread  through 
the  air,  for  sporules  and  mycelia  of  Tricophyton  tonsurans  and 
A  chorion  Schonleinii  have  been  found  floating  in  the  atmosphere 
of  wards  occupied  by  patients  suffering  from  diseases  of  the  skin. 

Vitiation  by  Combustion. 

There   are   three   kinds   of   mineral   coal — lignite,   anthracite 
or  smokeless  coal,  and  bituminous  coal.     Lignite  is  a  deposit 
intermediate  in  its  characters  between  peat  and  coal.     In  some 
parts  of  Germany,  considerable  deposits  occur;  and  it  is  there 
often    used   both   for    domestic    and    manufacturing   purposes. 
It  is  a  poor  fuel  compared  with  coal.     Bituminous  coal  is  used 
exclusively  in  the  manufacture  of  illuminating  gas;  it  usually 
furnishes  about  59  per  cent,  of  solid  carbon  (smokeless),  33  per 
cent,  of  volatile  hydrocarbons  (smoke  producing),  and  8  per  cent, 
of  ash.     Anthracite  is  a  sort  of  natural  coke,  most  of  its  gases 
having  been  driven  off  during  the  process  of  formation.     Bitu- 
minous coal  is  generally  used  for  domestic  fireplaces,  although 
anthracite,  being    smokeless  (no  soot),  when  used  in  properly 
constructed  stoves,  would  be  far  preferable.     Bituminous  coal 
when  burnt  in  an  open  fireplace  gives  off  nearly  three  times  its 
weight   of  carbonic   acid,   small   quantities  of  carbonic   oxide, 
sulphurous  acid,  bisulphide  of  carbon,  sulphuretted  hydrogen, 
and  steam.     About  i  per  cent,  is  given  off  as  fine  particles  of 
carbon  or  soot  and  tarry  matters.     One  pound  of  coal  requires 
240  cubic  feet  of  air  for  complete  combustion 

12 


178  HYGIENE   AND    PUBLIC    HEALTH 

Illuminating  gas  is  obtained  by  the  destructive  distillation 
of  coal  in  closed  retorts,  without  access  of  air.  The  gas  is 
subsequently  purified  by  condensation  to  remove  tar  and  water, 
and  its  temperature  is  reduced  to  about  60°  F.  If  the  tempera- 
ture of  the  gas  is  lowered  below  58°  F.,  naphthaline  and  other 
valuable  illuminants  are  deposited,  and  the  gas  is  impoverished. 
The  crude  gas  is  then  passed  through  coke  scrubbers,  v/hich 
are  large  chambers  so  arranged  as  to  offer  an  extended  surface, 
constantly  sprayed  with  water,  to  the  gas.  The  water  absorbs 
from  the  gas  nearly  the  whole  of  the  ammonia  and  the  remain- 
ing tarry  matters,  whilst  a  certain  quantity  of  the  ammoniacal 
and  sulphur  compounds  are  removed.  This  water  impregnated 
with  ammonia  and  its  compounds  forms  the  "  gas  Hquor  "  or 
crude  ammoniacal  liquor  of  commerce,  which  is  conducted  to 
the  tar  well.  The  gas  is  then  led  on  to  the  purifiers,  formed  of 
lime  or  sesquioxide  of  iron,  or  both,  and  here  the  carbonic  acid, 
sulphuretted  hydrogen,  bisulphide  of  carbon,  sulphocyanides, 
and  other  offensive  sulphur  compounds,  are  removed,  or  at 
least  reduced  in  the  gas  to  a  practically  unimportant  quantity. 
Thus  the  "  spent  hme,"  which  absorbs  cyanogen  and  sulphur 
compounds  in  addition  to  sulphuretted  hydrogen,  is  peculiarly 
offensive.  The  purified  gas  is  stored  in  gasometers,  which  are 
sunk  in  the  earth  to  a  considerable  depth,  water  being  used  as 
a  seal  to  prevent  the  escape  of  the  gas.  The  standard  adopted 
by  the  Metropolitan  Gas  Referees  requires  all  gas  to  be  quite  free 
from  sulphuretted  hydrogen;  the  maximum  of  sulphur  (in 
compounds  other  than  H.,S)  must  not  exceed  17  grains  per  100 
cubic  feet,  nor  the  ammonia  4  grains  per  100  cubic  feet. 

When  purified,  coal  gas  contains,  on  an  average:  hydrogen, 
46  per  cent. ;  marsh  gas,  37  per  cent. ;  carbonic  oxide,  7  per  cent. ; 
illuminants  (ethylene,  acetylene),  5  per  cent.;  nitrogen,  sul- 
phurous acid,  etc.,  5  per  cent.  The  products  of  combustion  of 
coal  gas  are  carbonic  acid,  50  to  60  per  cent.;  water,  16  per 
cent. ;  variable  traces  of  carbonic  oxide — least  when  combustion 
is  most  perfect — sulphurous  acid  and  ammonia.  One  cubic  foot 
of  average  gas  combines  with  the  oxygen  of  from  5  to  8  cubic 
feet  of  air,  and  produces  when  burnt  about  ^  cubic  foot  of  CO.,, 
and  from  o-2  to  0-5  grain  of  SO.,;  and  it  is  able  to  raise  the  tem- 
perature of  31,290  cubic  feet  of  air  1°  F. 

A  common  gas  burner  consumes  on  an  average  about  4  cubic 
feet  of  gas  per  hour,  and  furnishes,  therefore,  about  2  cubic 


AIR    AND    VENTILATION  I79 

feet  of  CO.,  in  that  time.  If  this  CO.,  is  to  be  broupjht  down  to 
0-6  per  mille,  10,000  cubic  feet  of  fresh  air  would  have  to  be 
supphed  per  hour  for  each  such  burner.  But  this  is  not  necessary; 
and  indeed,  when  adequate  measures  are  adopted  for  purifying 
coal  gas,  its  products  of  combustion  contain  but  little  impurity 
besides  COj.  It  is  therefore  generalty  considered  that  about 
1,200  cubic  feet  of  fresh  air  supply  is  amply  sufficient  for  every 
cubic  foot  of  gas  consumed.  A  "  standard  "  sperm  candle 
(six  to  the  pound),  and  burning  120  grains  per  hour,  gives  off 
about  04  cubic  foot  of  COg  per  hour;  and  one  cubic  foot  of  CO.2  is 
produced  by  the  combustion  of  about  300  grains  of  oil  in  a  lamp. 

The  sulphurous  acid  in  the  air  of  towns,  where  coal  is  largely 
consumed,  may  cause  the  rain  to  be  acid,  and  has  a  very 
destructive  effect  on  vegetation,  mortar,  and  the  softer  kinds  of 
building  stone.  The  products  of  combustion  of  coal  gas  usually 
escape  into  the  air  of  the  rooms  where  the  gas  is  burnt,  and 
serve  to  intensify  the  ill-effects  on  health  of  air  already  vitiated  by 
respiration.  Carbonic  acid  when  present  in  the  air,  even  to  the 
extent  of  2  per  cent.,  if  unmixed  with  other  impurities,  appears  to 
have  little,  if  any,  effect  upon  health;  but  above  this  quantity  it 
may  produce  headache  and  nausea,  and  if  present  to  the  extent 
of  10  per  cent.,  or  even  less,  it  may  produce  rapidly  fatal  results. 
Carbonic  oxide,  on  the  other  hand,  is  very  poisonous.  As  little 
as  0-4  per  cent,  in  the  air  may  cause  death  from  asphyxia,  the 
gas  uniting  with  the  haemoglobin  of  the  red  corpuscles  and 
displacing  the  oxygen,  so  that  the  red  corpuscles  can  no  longer 
act  as  carriers  of  oxygen  to  the  tissues,  and  failure  of  the  chief 
nervous  centres  results.  It  therefore  acts  as  a  powerful  narcotic, 
and  exerts  its  effects  in  a  most  insidious  manner;  for  being 
destitute  of  odour  and  not  causing  any  irritation  of  the  air- 
passages  when  inhaled,  it  may  be  breathed  unconsciously  by 
the  victim,  who  quickly  experiences  a  loss  of  the  power  of  move- 
ment, and  even  of  any  desire  to  make  an  effort  to  escape  from  the 
poisoned  atmosphere. 

The  sulphurous  acid  and  soot  in  the  general  air  of  towns 
like  Manchester,  Liverpool,  and  London,  appear  to  have  no 
very  marked  effect  on  healthy  people ;  but  they  are  undoubtedly 
injurious  to  many  asthmatics  and  to  people  suffering  from 
bronchitis.  During  dense  fogs  the  mortality  from  lung  diseases 
always  greatly  increases.  Yellow  town  fogs  are  due  to  the  sus- 
pended particles  of  moisture  in  the  air  (which  constitute  a  mist) 


l8o  HYGIENE    AND    PUBLIC    HEALTH 

becoming  enveloped  in  a  greasy  coat  of  mixed  carbon  and  hydro- 
carbons. The  mist  is  thus  rendered  yellow  and  opaque,  the 
light  of  the  sun  cannot  penetrate,  whilst  the  sulphurous  products 
contained  in  the  fog  are  extremely  irritating  to  the  respiratory 
mucous  membranes. 

Corfield  has  called  attention  to  cases  of  relaxed  and  ulcerated 
sore  throat  caused  by  sHght  escapes  of  coal  gas  into  houses  by 
defective  pipes  and  burners.  Coal  gas  also  occasionally  finds 
its  way  into  houses  from  leaky  or  fractured  mains  in  the  street. 
The  gas  passes  through  the  soil  and  escapes  under  the  base- 
ment floor,  or  even  finds  its  way  up  the  walls  behind  panelhng. 
When  the  escape  is  large  in  amount,  the  effects  produced  on 
persons  inhahng  the  gas  are  of  an  asphyxial  type  due  to  the 
contained  carbonic  oxide;  but  when  the  escape  is  small,  but 
long  continued,  the  sulphur  compounds,  and  especially  the 
bisulphide  of  carbon,  appear  to  be  the  injurious  factors  affecting 
the  throat.  These  effects  of  escape  of  gas  would  probably  be 
most  intense  where  the  gas  is  insufficiently  purified  after  manu- 
facture. 

The  method  usually  adopted  for  testing  the  soimdness  of  gas- 
pipes  and  fittings  is  to  subject  them  to  air  pressure  by  means 
of  a  force  pump.  A  pressure  gauge  is  attached  to  one  of  the 
burners,  and  air  is  forced  into  some  other  connected  pipe  until 
a  pressure  of  5  or  6  inches  of  water  is  registered  on  the  gauge, 
when  the  stopcock  on  the  force  pump  is  closed.  If  the  pressure 
gauge  reading  is  not  maintained  during  a  few  minutes,  the  pipes 
or  fittings  are  unsound. 

Foul-smeUing  sulphur  compounds  may  also  gain  access  to  the 
atmosphere  of  occupied  rooms  from  defective  chimney  flues. 
In  testing  a  chimney  flue,  the  outlet  should  be  sealed  from  the 
roof,  and  one  or  more  smoke  rockets  discharged  from  the  fire- 
place opening,  which  must  be  sealed  with  a  large  piece  of 
gummed  paper  immediately  after  the  hghted  rockets  have  been 
placed  up  the  chimney;  the  smoke  will  then  escape  at  any 
defective  parts  of  the  flue. 

Vitiation  of  Air  from  Decomposition  of  Organic  Matters. 
Animal  and  vegetable  organic  matters  in  cesspools  and  in 
badly  constructed  sewers  and  drains  ferment  and  putrefy, 
disengaging  gases,  some  of  which  are  foetid  and  highly  complex 
bodies,    probably    carbo-ammoniacal    and    allied    in    chemical 


AIR   AND   VENTILATION  l8l 

constitution  to  the  compound  ammonias  (methylaminc  and 
ethylamine),  whilst  others  are  the  simple  gases,  carbonic  acid, 
sulphuretted  hydrogen,  ammonium  sulphide,  carbon  l^isulphide, 
carburetted  hydrogen,  nitrogen,  etc.  Recent  research  tends  to 
show  that  the  organic  vapours  arising  from  decomposition  of 
animal  substances  may  contain  traces  of  the  animal  alkaloidal 
substances — ptomaines  and  leucomaines — -which  are  contained  in 
the  fffical  and  urinary  excretions  of  the  animal  body,  and  which 
exert  a  directly  poisonous  action  on  the  system.  The  carbo- 
ammoniacal  vapours  have  a  strongly  offensive  odour,  and  are 
found  in  the  air  of  cesspools  and  sewers  where  fermentative  pro- 
cesses are  in  action.  The  suspended  particles  in  cesspool  or 
sewer  air  are  dead  organic  debris  and  hving  organisms  (bacteria, 
moulds  and  fungi,  and  their  spores). 

The  micro-organisms — the  bacteria  and  fungi — are  constituents 
of  sewer  air  to  which  attention  has  been  lately  most  directed. 
The  net  result  of  these  observations  goes  to  show  that,  contrary 
to  what  might  have  been  expected,  sewer  air  is  under  ordinary 
conditions  remarkably  free  from  the  microbes  which  are  capable 
of  cultivation  on  solid  nutrient  media  at  ordinary  temperatures. 
By  ordinarj^  conditions  are  meant  sewers  of  modern  construction, 
well  laid  with  good  gradients,  and  therefore  comparatively  free 
from  deposits. 

Several  observers  have  shown  that  sewer  air  generally  possesses 
a  relatively  less  number  of  microbes,  capable  of  forming  colonies 
on  cultivation,  than  the  atmospheric  air  outside;  and  Mr. 
Parry  Laws'  investigations  tend  to  prove  that  the  microbes 
in  sewer  air  are  derived  from  the  organisms  usually  present  in 
atmospheric  air,  and  are  not  identical  with  those  found  in  sewage. 
The  microbes  in  sewer  air  are  chiefly  moulds,  whilst  those  in 
sewage  belong  to  the  class  of  bacilli.  The  explanation  appears 
to  be  that  the  internal  walls  of  sewers  are  more  or  less  wet 
or  moist,  and  it  is  assumed,  probably  with  reason,  that  the 
microbes  in  the  sewer  air  adhere  to  the  damp  surfaces,  and 
are  thus  prevented  from  floating  in  the  air.  This  reasoning 
is  strengthened  by  what  is  already  known  of  the  presence  of 
microbes  in  atmospheric  air  generally;  for  in  dusty  dry  weather 
they  are  found  in  far  larger  numbers  than  in  damp  weather 
or  after  rainfall.  In  well-made  sewers  the  sewage  is  borne 
away  from  the  houses  in  a  fresh  and  undecomposed  condition; 
but  in  old  and  defective  sewers,  and  even  in  moderately  good 


l82  HYGIENE   AND   PUBLIC   HEALTH 

ones  when  the  temperature  of  the  air  is  high,  and  the  amount 
of  diluting  water  is  small — as  during  hot  and  dry  summers — 
putrefactive  bacteria  undergo  enormous  multiplication,  fermen- 
tative changes  are  set  up  in  the  sewage,  and  gases  are  formed 
which  bubble  up  and  break  upon  the  surface  of  the  liquid. 

It  was  demonstrated  as  long  ago  as  1871  by  Professor  Frank- 
land,  that  liquids  flowing  smoothly  in  channels  give  off  no  solid 
particles  to  the  air,  and  that  even  considerable  agitation  re- 
sulting in  frothing  may  not  cause  any  perceptible  increase  of 
the  solid  particles  in  the  superincumbent  air,  but  that  the 
bursting  of  bubbles  of  gas  in  a  liquid  had  a  marked  effect  in 
disseminating  soHd  particles.  The  experiments  of  Haldane  and 
Camelly,  which  have  been  more  recently  made,  also  show  that 
splashing  in  a  sewer,  which  may  be  caused  by  branch  drains 
entering  near  the  crown  of  the  sewer,  is  productive  of  dissemina- 
tion of  micro-organisms  in  the  air. 

The  earlier  investigations  of  Mr.  Parry  Laws  and  Dr.  Andrewes 
on  the  micro-organisms  of  sewage  and  sewer  air  tended  to  show 
that  sewer  air  has  no  power  of  taking  up  bacteria  from  the  sewage 
with  which  it  is  in  contact.  The  authors  concluded  that  the 
possibihty  of  the  existence  of  the  bacillus  of  typhoid  in  the  air  of 
our  sewers  is  infinitely  remote.  They  also  experimented  on  the 
vitality  of  the  bacillus  of  typhoid  in  sewage.  They  concluded,  as 
the  result  of  their  investigations,  that  sewage  does  not  form  a 
medium  in  which  much,  if  any,  growth  of  the  bacilli  is  possible 
under  natural  conditions.  The  death  of  the  bacilli  in  sewage 
is  probably  only  a  matter  of  a  few  days,  or  at  most  one  or  two 
weeks.  But  this  degree  of  resistance  may,  nevertheless,  be 
sufficient  to  allow  of  their  being  carried  in  sewage  to  remote 
distances,  and  of  their  being  able  to  produce  disastrous  results 
should  they  gain  access  to  any  water  supply. 

Horrocks  found  that  Bacillus  prodigiosus  added  to  sewage  may 
be  recovered  from  the  air  of  drains  and  sewers,  even  when  the 
sewage  is  flowing  smoothly  and  without  splashing.  In  one 
experiment  [he  B .  typhosus  was  found  in  the  air  of  a  drain  through 
which  the  stools  of  an  enteric  fever  patient  had  been  slowly 
passed.  He  also  recovered  B.  coli  from  the  air  of  one  of  the  main 
sewers  of  the  town,  about  10  feet  above  the  flowing  sewage.  The 
experimental  results  obtained  by  Horrocks  will  tend  to  revive  the 
opinion,  formerly  held,  that  sewer  and  drain  air  may  be  the 
means  of  spreading  infective  diseases,  such  as  enteric  fever,  and 


AIR   AND   VENtlLAtlON  1 83 

diarrhoea.  They  also  showed  that  the  disconnecting  trap  on 
a  house  drain  prevents  the  passage  of  bacteria  present  in  sewer 
air  into  the  house  drains. 

Horrocks  conchides  that  specific  bacteria  present  in  sewage 
may  be  ejected  into  the  air  and  carried  by  air  currents  through 
drains,  sewers,  and  ventilation  pipes  by  (a)  the  bursting  of 
bubbles  at  the  surface  of  the  sewage,  (b)  the  separation  of  dried 
particles  from  the  walls  of  the  sewers  and  pipes,  and  probably 
(c)  by  the  ejection  of  minute  droplets  from  flowing  sewage. 

The  more  recent  work  of  Andrewes  confirms  that  of  Horrocks, 
for  he  has  shown  that  under  many  ordinary  circumstances 
characteristic  sewage  bacteria  are  to  be  found  intermittently  in 
the  air  of  drains  and  sewers.  The  streptococci  of  drain  air 
correspond  with  those  of  sewage,  and  only  to  a  sHght  extent  with 
those  found  in  the  outer  atmosphere.  Similarly  the  bacilli  of  the 
colon  group  obtained  from  drain  air  correspond  with  those 
present  in  sewage;  fresh  air  contains  practically  no  ba.cilli  of  this 
character.  The  bacteria  derived  from  sewage  probably  form 
but  a  small  proportion  of  the  total  bacterial  flora  present  in 
sewer  air,  unless  there  is  much  splashing  or  agitation  of  the 
sewage  in  the  vicinity.  Still,  they  are  liable  to  be  present,  even 
although  their  numbers  are  relatively  small.  Andrewes  is  of 
opinion  that  the  failure  to  identify  these  organisms  in  sewer  air 
in  former  experiments  was  due  to  the  fact  that  the  special 
selective  media,  which  are  now  available  for  the  cultivation  of 
various  classes  of  micro-organisms,  were  then  unknown. 

Chemical  examination  shows  that  sewer  air  is  subject  to 
wide  variations.  A  sample  of  air  taken  from  a  choked  sewer 
in  Paris  was  found  by  Parent  Duchatelet  to  contain  only  1379  P^'' 
cent,  of  oxygen,  and  as  much  as  299  per  cent,  of  sulphuretted 
hydrogen.  The  air  of  closed  cesspools  in  Paris  must  often 
have  been  very  polluted  to  have  caused  those  symptoms  of 
partial  asphyxia  from  which  the  workmen  employed  to  empty 
them  occasionally  suffered. 

Where  the  quantity  of  sulphuretted  hydrogen  has  been  re- 
latively great,  sudden  death  has  in  some  instances  resulted 
amongst  those  who  have  opened  cesspools.  The  same  results 
have  followed  when  men  have  entered  foul  sewers.  Uncon- 
sciousness may  be  produced  when  there  is  as  little  as  02  per 
cent,  of  HoS  in  the  air.  Whenever  it  is  necessary  to  enter  an 
old  or  foul  sewer  (or  cesspool)  the  following  precautions  should 


184  HYGIENE   AND   PUBLIC   HEALTH 

be  taken:  Open  the  lids  of  the  two  adjacent  manholes  and 
leave  open  for  some  time,  so  as  to  obtain  free  ventilation  and 
dilution  of  the  gas;  then  cautiously  lower  a  hghted  candle 
into  the  sewer,  which  must  not  be  entered  unless  the  candle 
burns  brightly.  If  there  is  a  likelihood  of  explosive  gases  being 
present  in  the  sewer,  a  miner's  safety  lamp  should  be  lowered,  or 
a  mouse  in  a  cage;  in  the  latter  case,  if  the  mouse  is  lively 
after  ten  minutes  in  the  sewer,  it  will  be  safe  for  a  man  to  enter 
it.  Whenever  circumstances  appear  to  warrant  it,  the  man 
should  have  a  strong  rope  tied  around  his  shoulders,  so  that  he 
could  be  extricated  by  a  comrade,  who  should  always  be  in 
readiness;  and  if  he  should  have  to  crawl  along  the  sewer,  a 
rope  should  also  be  securely  tied  to  his  ankles,  so  that  he  may 
be  drawn  back  if  overpowered  by  gas.  For  men  overpowered 
by  sewer  gas  the  best  remedy  is  artificial  respiration,  or  oxygen 
inhalation,  if  available.  Liquor  strychniae  should  be  injected 
subcutaneously,  and  artificial  warmth  applied  to  the  extremities. 

In  the  London  sewers  the  air  is  generally  fairly  pure.  The 
most  impure  sample  taken  by  Dr.  Russell  from  the  Paddington 
sewers  was  found  to  contain  0-51  vols.  CO.,,  207  vols.  O,  and 
7879  vols.  N  in  100  vols. 

The  breathing  of  drain  or  sewer  air  undoubtedly  at  times 
produces  injury  to  health.  This  is  especially  the  case  when 
people  are  exposed  to  escapes  of  drain  or  sewer  air  into  houses 
for  a  long  period.  The  dose  of  the  poison  may  not  be  sufficiently 
great  at  any  one  time  to  cause  the  acute  symptoms  above 
described;  but  the  long-continued  inhalation  of  diluted  sewer 
air,  as  in  houses  with  defective  drainage,  tends  to  produce  a 
general  loss  of  health  (especially  in  children),  which  is  shown  in 
various  ways,  as  by  anaemia,  loss  of  appetite,  prostration, 
diarrhoea,  fever,  headache,  vomiting,  or  sore  throat;  or  it  may 
be  that  only  a  condition  of  depressed  vitality  is  produced,  which 
offers  but  slight  resistance  to  attacks  of  acute  disease. 

Occasionally  a  severe  form  of  tonsillitis  attacks  the  occupants 
of  a  badly  drained  house.  This  form  of  tonsillitis,  which  is 
now  generally  recognized  as  "  sewer  air  throat  "  is  marked  by 
great  infiannnatory  swelling  of  the  tonsils,  very  foul  tongue 
and  gastric  derangement,  accompanied  by  severe  headache 
and  intense  depression.  The  temperature  of  the  body  is  often 
not  much  raised,  certainly  not  to  a  height  proportionate  to 
the  severe  symptoms;  and  this  low  temperature,  together  with 


AIR    AND   VENTILATION  185 

the  intense  prostration,  are  characteristic  of  many  illnesses 
resulting  from  septic  infection  of  the  system.  Symptoms  of 
blood-poisoning,  as  shown  by  boils  and  carbuncles,  petechial 
rashes,  glandular  enlargements,  lymphangitis,  phlebitis,  albu- 
minuria, and  fever,  have  been  noted  by  some  observers,  and 
attributed  to  long-continued  exposure  to  drain  or  sewer  air 
escapes  into  houses.  To  what  particular  constituents  of  sewer 
air  we  are  to  attribute  these  and  allied  illnesses,  it  is  difficult  to 
determine.  The  attacks  of  tonsilhtis,  diarrhoea,  etc.,  are  not 
protective  from  future  attacks;  and  although  there  is  some 
evidence  of  the  "  sewer  air  throat  "  being  contagious  and  directly 
transmissible  from  person  to  person,  it  is  equally  likely  that 
'examples  of  apparently  direct  contagion  are  really  due  to  ex- 
posure to  a  common  cause. 

Probably  on  account  of  the  violent  splashing  in  soil  pipes,  etc., 
there  are  more  possibihties  of  conveyance  of  infection  through 
the  drainage  system  of  a  building  than  through  the  air  of  a  sewer. 

Inquiries  have  from  time  to  time  been  made  into  the  health 
of  sewer  men,  who  are  constantly  engaged  in  flushing  and  re- 
moving deposits  from  sewers.  The  results  of  such  investigations 
lead  rather  to  the  belief  that  the  constant  breathing  of  sewer 
air  is  not  injurious  to  health  and  life.  But  it  must  be  remembered 
that  these  are  picked  men  in  the  prime  of  life,  who,  now  at 
any  rate,  generally  work  in  well-ventilated  sewers,  where  the 
air  is  not  abnormally  foul,  and  that  these  inquiries  have  not 
been  very  exhaustive.  It  appears,  however,  that  they  suffer 
somewhat  from  ophthalmia,  and  that  the  occupation  tends 
greatly  to  aggravate  venereal  disease.  The  work  is  certainly 
unsuited  to  some  constitutions,  as  many  men  are  obliged  to  give 
it  up  after  a  short  trial. 

It  seems  only  fair  to  assume  now,  in  the  hght  of  our  present 
knowledge,  that  the  men  engaged  in  this  occupation  undergo  a 
species  of  accHmatization,  so  to  speak,  to  the  influences  to 
which  they  are  exposed.  The  long-continued  inhalation  or 
ingestion  of  tainted  air  may  be  considered  as  conferring  im- 
munity upon  the  individual  so  occupied  from  diseases  bred  by 
sewer  air,  which  would  readily  attack  one  whose  system  had 
not  been  exposed  to  the  acclimatizing  process. 

Diarrhoea  and  dysenteric  diarrhoea  are  sometimes  caused  by 
breathing  air  contaminated  with  excretal  emanations.  This  is 
one  of  the  many  causes  of  the  summer  diarrhoea  which  is  so 


l86  HYGIENE   AND    PUBLIC    HEALTH 

common  in  a  hot  and  dry  season  in  the  badly  drained  districts 
of  large  towns. 

There  is  now  being  accumulated  a  very  considerable  body  of 
evidence  to  show  that  puerperal  fever  may  be  produced  by 
sewer  or  drain  emanations  finding  their  way  into  the  chamber 
of  a  lying-in  woman ;  whilst  under  similar  conditions  septic  peri- 
tonitis may  ensue  after  a  miscarriage.  Erysipelas,  pyemia,  septi- 
caemia, and  hospital  gangrene,  if  not  caused  by  such  emanations, 
are  certainly  favoured  by  conditions  of  excretally  polluted  air. 

The  exact  relationship  subsisting  between  attacks  of  enteric 
fever  or  diphtheria  and  the  previous  exposure  of  the  patient  to 
the  inhalation  of  emanations  from  sewers,  cesspools,  or  drains 
has  not  yet  been  fully  elucidated.  The  theory  which  is  now 
usually  accepted  is  that  exposure  to  drain  or  sewer  emanations 
predisposes  the  person  so  exposed  to  an  attack  of  either  disease, 
both  by  depressing  the  powers  of  resistance  of  the  system  and  by 
inducing  morbid  conditions  in  the  throat  or  ahmentary  canal  that 
favour  the  growth  and  virulence  of  the  specific  organism  should 
it  happen  to  obtain  access.  It  ?.s  now  recognized,  so  far  at  least 
as  regards  diphtheria,  that  the  specific  organism  maybe  present 
in  the  throat  of  apparently  healthy  persons,  but  unpossessed 
of  virulent  properties.  Exposure  to  defective  sanitary  condi- 
tions may  restore  virulence  to  the  organism  either  by  offering 
it  a  suitable  nidus  for  its  growth,  or  by  exciting  the  activity  of 
other  organisms  (streptococci)  which  favour  the  renewal  of 
virulence  of  the  diphtheria  bacilli  (symbiosis). 

When  excretal  or  other  offensive  emanations  are  given  off  into 
the  open  air,  they  are  much  less  liable  to  cause  disease  or  injury 
to  health  than  when  they  find  their  way  into  confined  spaces,  such 
as  narrow  courts  or  the  interiors  of  houses.  In  the  open  air  of 
the  country  they  are  rapidly  diluted  and  oxidized,  and  rendered 
practically  harmless.  In  this  way  we  can  account  for  the 
excellent  health  enjoyed  by  the  workmen  on  sewage  farms 
and  by  those  who  live  in  the  neighbourhood,  as  well  as  by  the 
men  engaged  at  sewage  works;  but  the  process  of  habituation 
may  also  perhaps  be  partly  responsible  for  such  good  results. 
There  is  some  evidence  that  since  the  introduction  of  the  septic 
tank  system  of  sewage  treatment,  and  the  discharge  of  the 
putrid  or  septic  effluent  upon  artificial  filters  (sprinkler  beds) 
or  upon  land,  the  near  neighbourhood  of  town  sewage  works 
has  in  some  cases  been  depreciated  by  effluvia  which  are  stated 


AIR   AND    VENTILATION  187 

to  be  injurious  to  the  health  of  the  residents  in  the  affected  zone. 
Such  effluvia  may  be  carried  at  times  a  considerable  distance  by 
the  wind;  but  only  those  residing  within  a  short  distance  of 
the  works  are  likely  to  be  affected  in  health. 

Grossly  polluted  rivers,  which  give  rise  during  hot  weather  to 
most  offensive  emanations,  may  at  times  cause  injury  to  health. 
The  same  may  be  said  of  effluvia  from  manure  manufactories, 
soap  works,  tallow  works,  and  other  offensive  trades,  and  also 
of  the  effluvia  from  putrefying  animal  bodies,  given  off  into  the 
open  air;  it  being  a  matter  of  experience,  that  occasional  attacks 
of  sickness  and  diarrhoea  and  chronic  distaste  for  food  may  be 
produced  by  offensive  emanations,  even  when  discharged  at  a 
height  from  lofty  chimneys.  The  air  of  crowded  graveyards  and 
vaults  may  contain  excess  of  CO.,  and  organic  vapours  (carbo- 
ammoniacal) ;  if  such  polluted  air  rises  from  the  soil  and  escapes 
into  buildings,  it  may  cause  serious  sickness  among  the  occu- 
pants; but  when  the  vapours  escape  into  the  open  air,  even  in 
the  midst  of  towns,  no  marked  injurious  effects  appear  to  arise. 

The  air  over  marshes  is  impure  from  the  large  amount  of 
decaying  vegetation  in  the  water  and  soil.  Carbonic  acid,  sul- 
phuretted hydrogen,  and  carburetted  hydrogen  (marsh  gas), 
are  generally  present  in  some  excess,  together  with  decaying 
organic  matter,  both  in  the  form  of  vapour  and  of  suspended 
matter.  The  suspended  matters  in  marsh  air  consist  of  vege- 
table debris,  diatoms,  algse,  fungi,  bacteria,  and  other  micro- 
organisms. In  some  marshes  the  air  is  very  rich  in  H2S,  and 
the  symptoms  of  ansemia  and  prostration  have  been  held  to  be 
due  to  this  fact. 

Vitiation  of  Air  in  Industrial  Occupations. 

Two  kinds  of  occupation  have  long  been  recognized  as  hurtful, 
viz.,  (i)  those  that  give  rise  to  mechanical  or  chemical  irritation 
of  the  lungs  by  trade  dusts  or  vapours;  and  (2)  those  in  which 
the  workers  are  exposed  to  great  variations  of  temperature. 

Although  in  some  trade  processes  injurious  gases  are  evolved 
and  escape  into  the  air  that  must  be  respired  by  the  workmen 
engaged  in  the  trade,  yet  the  vast  majority  of  industrial  occu- 
pations are  injurious,  or  otherwise,  according  to  the  amount  and 
nature  of  the  dusi  which  is  produced.  As  subsidiary  factors  of 
high  importance  must  be  considered  the  conditions  under  which 
the  dust-producing  work  is  carried  on,  whether  in  the  open  air, 


i88 


HYGIENE   AND   PUBLIC   HEALTH 


in  well-ventilated  workshops  or  factories,  or  in  overcrowded 
close  rooms  at  a  high  temperature  and  with  the  air  saturated 
with  moisture.  The  long-continued  inhalation  of  dust  tends  to 
produce  disease  of  the  lungs,  especially  bronchitis,  emphysema, 
and  interstitial  pneumonia,  and  it  predisposes  to  fibroid  phthisis. 
The  source  of  the  dust,  whether  vegetable  or  mineral,  is  not  so 
important  as  the  character  of  the  particles  which  compose  it. 
The  most  injurious  kinds  are  those  whose  particles  are  hard, 
sharp,  and  angular,  which  become  impacted  in  the  walls  of  the 
bronchioles  or  air  cells  of  the  lungs,  are  not  easily  expectorated, 
and  set  up  irritation  and  chronic  inflammation  of  the  tissues 
around.  The  soft  or  rounded  particles  are  not  capable  of  doing 
nearly  so  much  mischief.  Coal-miners'  lungs  are  often  after 
death  found  to  be  black  (anthracosis)  from  the  impaction  of  fine 
particles  of  coal  dust  in  the  pulmonary  alveoli,  without  the  in- 
dividual having  manifested  any  pulmonary  symptoms  during  life. 


Comparative  Mortality  of  ]\Iales,  Twenty-five  to  Sixty-five  Years 
of  age,  in  certain  dust-inhaling  occupations  from  phthisis 
AND  Diseases  of  the  Respiratory  Organs. i 


Phthisis. 

1        Diseases 
of  the 
Respiratory 
Organs. 

Phthisis  nnd 

Diseases  of  the 

Respiratory 

Organs. 

Coal  miner          .... 
Carpenter,  joiner 
Baker,  confectioner    . 
Plumber,  painter,  glazier   . 
Mason,  builder,  bricklayer 
Wool  manufacturer    . 
Cotton  manufacturer 
Ouarryman  (stone,  slate)    . 

Cutler 

File  maker          .... 
Earthenware  manufacturer 
Cornish  miner    .... 

126 
204 
212 
246 
252 

257 
272 
308 
371 

433 
473 
690 

202 

133 
186 

185 
201 
205 
271 
274 
389 
350 
645 
458 

328 

337         ! 

39S 

431 

453 

462 

543 
582 
760 

783 
1,118 
1,148 

All  males  (England  and  Wales) . 
Fishermen          .... 

220 
108 

182 
90 

402 
198 

The  above  table  gives  the  comparative  mortalit}^  figures 
for  males  in  different  dust-inhaling  occupations,  the  mortality 
figure  amongst  all  males  between  twenty-five  and  sixty-iive  years 
of  age  in  England  and  Wales  being  taken  at  1,000.     It  is  impor- 


1  Dr.   Ogle's  Report,  Supplement  to  the  45th  Annual  Report  of  the 
Registrar-General. 


AIR  AND   VENTILATION  189 

tant  to  note  that  the  column  under  phthisis  represents  the  tuber- 
cular form  of  this  disease,  but  undoubtedly  includes  many  cases 
of  fibroid  phthisis  as  well. 

More  recently  Dr.  Tatham  has  furnished  a  valuable  contribu- 
tion^ on  the  varying  rates  of  mortality  among  men  engaged  in 
different  occupations,  the  main  conclusions  being  based  upon  the 
deaths  that  occurred  during  the  three  years  1890-92  among  males 
between  twenty-five  and  sixty-five  years  of  age — the  period 
during  which  the  effect  of  occupation  is  assumed  to  be  most 
marked,  and  in  which  the  proportion  of  occupied  males  is  largest. 
Taking  1,000  to  represent  the  mortahty  of  all  males  at  these  ages 
in  England  and  Wales,  the  comparative  mortality  figure  for  all 
occupied  males  was  953,  and  while  it  was  687  in  agricultural 
districts,  it  reached  to  1,248  in  industrial  districts.  The  com- 
parative mortahty  figures  of  males  from  twenty-five  to  sixty-five 
years  of  age  was  low  for  clergymen  (533),  gardeners  (553),  farmers 
(563),  school  teachers  (604),  farm  labourers  (632),  and  lawyers 
(821);  for  medical  men  it  was  966;  and  it  was  high  among 
brewers  (1,427),  general  labourers  in  industrial  districts  (1,509), 
publicans  (1,642),  costermongers  (1,652),  and  hotel  servants 
(1,725).  The  excessive  mortality  of  cutlers,  file  makers,  scissors 
makers,  and  nail  makers,  noted  in  previous  periods  of  observation, 
was  still  higher  in  1890-92;  and  slaters,  tilers,  wool,  silk,  and 
cotton  dyers,  potters,  glass  manufacturers,  tin  miners,  coal 
heavers  and  chimney  sweepers  again  showed  marked  excess  of 
mortality. 

In  Dr.  Tatham's  report  the  figures  bearing  upon  the  fatal  effects 
of  breathing  dust-laden  air,  or  air  fouled  in  other  ways,  have 
acquired  increased  value  from  the  careful  ehmination  of  the 
disturbing  influences  of  the  varying  age  proportions  of  persons 
engaged  in  different  occupations.  Taking  100  to  represent  the 
combined  mortality  from  phthisis  and  diseases  of  the  respiratory 
organs  among  those  engaged  in  agricultural  occupations,  the 
comparative  figures  from  these  diseases  among  those  engaged  in 
occupations  which  cause  dust  of  various  kinds  reaches  373  for 
file  makers,  407  for  cutlers  and  scissors  makers,  and  453  for 
potters  and  earthenware  manufacturers. 

That  coal  miners  should  stand  at  the  head  of  Ogle's  list,  as  re- 
gards freedom  from  lung  diseases,  is  somewhat  surprising,  con- 
sidering that  the  air  in  the  underground  passages  in  which  they 

1  Supplement  to  the  55th  Annual  Report  of  the  Registrar-General. 


igO  HYGIENE    AND   PUBLIC   HEALTH 

work,  even  in  the  best  ventilated  mines,  is  vitiated  by  respiration, 
combustion  of  lights,  and  blasting  agents,  which  throw  into  the 
air  much  COg,  CO,  HgS,  etc.  In  addition,  COg  and  CH^  are 
often  evolved  in  considerable  volumes  from  the  strata  cut  through 
by  the  shafts  and  borings,  and  the  air  in  the  workings  is  always 
thick  with  coal  dust.  Dr.  Ogle  explains  the  comparative  in- 
nocuity  of  coal  dust  in  causing  lung  disease  by  the  microscopical 
character  of  its  particles,  which  are  comparatively  free  from  sharp 
points  and  corners.  He  is  also  inclined  to  attribute  to  coal  dust 
a  special  property  of  hindering  the  development  and  arresting 
the  progress  of  tuberculosis — a  disease,  it  is  to  be  remembered, 
which  might  be  expected  to  be  very  fatal  to  coal  miners,  from  the 
fact  of  their  working  in  a  heated  vitiated  atmosphere,  and  being 
liable  to  sudden  alterations  of  temperature  in  going  to  and  leaving 
off  work.  Where  there  is  a  considerable  proportion  of  stony 
particles  in  the  coal,  lung  diseases  appear  to  be  favoured;  and 
this  no  doubt  accounts  for  the  fact  that  the  incidence  of  miners' 
phthisis  in  different  collieries  is  unequal. 

Experiments  upon  the  lower  animals  indicate  that  carboniferous 
particles  arrested  in  the  nasal  and  pharyngeal  passages,  and  after- 
wards swallowed,  may  pass  through  the  intestinal  epitheUum  and 
through  the  lymphatic  system,  finding  their  way  into  the  thoracic 
duct  and  thence  into  the  venous  circulation,  to  be  ultimately 
arrested  in  the  capillaries  of  the  lung.  These  experiments  also 
demonstrated  that  in  young  animals  the  carbon  particles  do  not 
readily  get  beyond  the  mesenteric  glands.  In  animals  and  men 
the  lungs  soon  rid  themselves  of  such  particles  when  the  broncho- 
tracheal  glands  are  healthy;  but  when  these  latter  have  become 
injured,  as  in  the  case  of  miners,  definite  anthracosis  supervenes. 

The  workers  in  coal  mines  are  liable  to  a  condition  of  the  eye- 
sight which  has  been  termed  "  miners'  nystagmus."  This  is 
essentially  a  disease  of  the  collier,  but  is  unknown  among  the 
younger  miners;  it  was  first  described  at  the  time  when  the 
illumination  in  collieries  was  considerably  reduced  by  the  intro- 
duction of  the  Davey  safety  lamp.  The  evidence  collected  points 
to  the  conclusion  that  the  condition  is  not  caused  by  awkward 
positions  of  the  body,  and  strain  of  the  eye  muscles,  but  is  really 
due  to  feeble  illumination  in  the  mine.  With  an  improvement 
in  the  ventilation  and  hghting,and  shorter  hours  of  work  in  mines, 
the  incidence  of  the  disease  shows  a  tendency  to  diminish. 

The  comparative  immunity  of  coal  miners  from  tubercle  is  not 


AIK    AND   VENTILATION 


191 


displayed  by  the  Cornish  or  tin  miners,  who  come  at  the  bottom  of 
the  hst.  Their  mortahty  from  lung  diseases  constitutes  nearly  two- 
thirds  of  their  total  mortality,  and  is  nearly  three  times  as  great 
as  that  of  Cornish  males  generally.  They  work  under  conditions 
of  heated  and  vitiated  air  like  the  coal  miners,  but  they  inhale  a 
sharp,  angular,  and  most  irritant  stone  dust,  instead  of  the  com- 
paratively smooth  coal  dust.  All  metalliferous  miners  working 
in  hard  stone  are  exposed  to  dust-inhalation;  but  those  who  are 
most  exposed  are  those  who  employ  drilling  or  boring  machines 
acting  by  percussion  (compressed  air).  A  jet  or  spray  of  water 
directed  upon  the  rock,  when  the  drill  is  at  work,  is  a  valuable 
means,  which  has  been  largely  adopted,  of  keeping  down  this 
dust.  Gold  miners  also  are  short-lived,  and  suffer  largely  from 
phthisis.  The  other  occupations  in  which  the  workers  are  ex- 
posed to  the  inhalations  of  stone  dust  are  masons,  builders,  and 
bricklayers,  who  carry  on  their  work  chiefly  in  the  open  air,  and 
have  a  lung  disease  figure  of  453;  stone  and  slate  quarrymen, 
who  also  mainly  work  in  the  open  air  (582) ;  and  the  earthenware, 
china,  and  pottery  manufacturers,  who  suffer  enormously  from 
pneumonia,  bronchitis,  and  emphysema  (potters'  asthma),  and 
phthisis.  Among  these  latter  the  lung  disease  mortahty  is 
nearly  the  same  as  that  of  the  tin  miners.  They  carry  on  their 
trade  in  close  and  heated  factories,  and,  besides  the  fine  irritating 
dust,  are  exposed  to  great  vicissitudes  of  temperature.  The 
chinaware  is  baked  with  flint  dust,  and  this  is  subsequently 
brushed  off  by  women,  the  process  being  known  as  "  china 
scouring."  This  process  is  especially  dangerous,  the  silicious 
constituents  of  the  dust  being  the  chief  cause  of  mischief. 

Cutlers  a.nd  file  makers,  needle,  pin,  and  tool  makers,  are  exposed 
to  metallic  dust  and  stone  dust  given  off  from  the  grindstones, 
and  they  suffer  largely  from  phthisis,  bronchitis,  and  pneumonia. 
File  makers  are  in  addition  liable  to  lead  poisoning,  from  their 
using  a  cushion  of  lead  on  which  to  strike  their  file.  In  these 
trade  processes  the  dust  should  be  collected,  as  far  as  possible, 
by  hoods  placed  immediately  over  the  benches  which  lead  into 
a  common  outlet  shaft,  the  draught  in  which  is  maintained  by  a 
revolving  fan.  Or,  where  hoods  are  inconvenient,  perforated 
metal  plates  may  be  let  into  the  benches  and  hopper  expansions 
of  the  outlet  shafts  fitted  immediately  below  these  plates;  the 
fan  then  pulls  air,  and  with  it  the  dust,  through  the  perforations 
of  the  metal  plates.    The  dust  from  the  common  outlet  shaft 


192  HYGIENE   AND   PUBLIC    HEALTH 

may  be  allowed  to  settle  in  a  dust  chamber,  or  be  arrested  by 
filtering  the  air  through  canvas  screens,  or  by  a  water  surface  or 
spray.  The  workers  should  be  made  to  wear  respirators  in  the 
more  dusty  rooms;  and  in  steel  grinding,  magnetic  shields  are 
useful  for  attracting  and  collecting  the  steel  dust.  In  the 
grinding  trades  the  grindstone  may  be  enclosed  in  a  hood  or 
casing  connected  to  a  powerful  exhaust  fan.  This  is  especially 
desirable  in  dry  grinding;  and,  where  necessary,  glass  may  be 
let  into  the  hood  to  permit  light  to  pass  to  the  grinding  surface. 
Dr.  Harold  Scurfield  has  recently  shown  (1908)  that  the  death- 
rate  of  grinders  from  phthisis  is  more  than  six  times  that  from 
respiratory  diseases,  and  nearly  three  times  that  of  the  average 
male  in  Sheffield;  also  that  in  the  case  of  cutlers  the  death-rate 
from  phthisis  is  nearly  three  times  that  from  respiratory  diseases, 
and  four  times  that  of  the  average  male  in  Sheffield.  The  first 
direct  result  of  this  form  of  dust-inhalation  is  an  irritation  of  the 
mucous  membrane  of  the  nasal  passages,  often  with  erosion  and 
ulceration,  followed  by  atrophy  and  loss  of  smell.  This  atrophy 
facilitates  the  entrance  of  dust  into  the  lungs  and  librotic 
inflammatory  masses  form,  which  ultimately  break  down,  leaving 
cavities  which  frequently  become  inoculated  with  the  tubercle 
bacilli.  Hence  those  who  contract  this  pneumoconiosis  arc  very 
liable  to  die  from  a  superimposed  tubercle  infection. 

In  brass  foundries  the  workers  (more  especially  the  turners, 
polishers,  and  filers)  inhale  a  metallic  dust  which  is  productive 
of  a  disease  formerly  called  "  brass  founders'  ague."  The 
symptoms  which  caused  Dr.  Greenhow  to  designate  the  disease 
brass  workers'  ague  are  shown  to  be  due  to  the  ingestion  of  a 
quantity  of  the  irritant  metallic  dust  sufficiently  large  to  cause 
vomiting  with  its  attendant  depression.  Brass  is  an  alloy  of 
copper  and  zinc,  in  the  proportion  of  about  three  to  one.  Prob- 
ably the  zinc  is  the  offending  ingredient,  though  possibly  the 
copper  may  have  some  additional  influence.  The  symptoms  are 
described  as  tightness  and  oppression  of  the  chest,  with  indefinite 
nervous  sensations  followed  by  shivering  and  profuse  sweating. 
The  illness  only  occurs  in  those  who  are  new  to  the  work,  or  who 
resume  work  after  an  absence  of  a  few  weeks.  The  men  who 
suffer  in  this  way  drink  freely  of  milk  and  promote  vomiting, 
the  best  treatment  that  could  be  devised  for  copper  or  zinc 
poisoning. 

Chronic    copper    poisoning    is    also    common    amongst    brass 


AIR    AND   VENTILATION  I93 

workers,  and  bronchitis  from  inhalation  of  the  irritant  dust.  Tlie 
leading  symptoms  of  chronic  copper  poisoning  are:  Anaemia, 
nausea  and  vomiting,  colic,  wasting,  headache  and  nervous 
symptoms,  and  a  green  line  (due  to  copper)  is  seen  at  the  bases 
of  the  teeth.  The  patient  also  suffers  from  profuse  sweatings 
which  stain  the  underlinen  a  greenish  colour,  itching,  skin  erup- 
tions, chronic  bronchial  catarrh,  and  later,  pulmonary  fibrosis. 
For  the  prevention  of  brass  founders'  ague  "  special  rules  "  are 
enforced  by  the  Chief  Inspector  of  Factories.  These  rules  apply 
only  to  the  casting  and  mixing  shops,  and  require  that  adequate 
means  be  provided  for  the  escape  of  noxious  fumes  and  dust,  that 
the  shops  be  cleaned  down  and  limewashed  every  year,  that  the 
workpeople  have  every  facility  for  personal  cleanliness,  and  are 
prohibited  from  eating  during  the  process  of  casting. 

The  operatives  in  cptton  factories  work  in  a  heated  atmosphere 
saturated  with  moisture  by  steam,  and  laden  with  filamentous 
particles  of  cotton  and  mineral  substances  used  for  sizing.  A 
standard  of  purity  of  the  air  is  now  enforced,  by  which  the  CO2 
may  not  exceed  o-og  per  cent,  in  the  artificially  moistened  sheds. 
In  order  to  avoid  the  consequences  of  heavy  steaming,  Haldane 
has  suggested  that  a  hne  spray  of  cold  water  should  be  employed 
instead  of  hot  steam.  In  woollen  factories  the  heat  is  not  so 
great,  and  there  is  less  dust  owing  to  the  wool  being  treated  with 
oil;  but  wool  sorters  are  liable  to  contract  anthrax  from  infected 
fleeces.  In  silk  mills,  dust  and  high  temperature  are  injurious  to 
the  material,  and  are  consequently  avoided. 

Millers  and  bakers  are  liable  to  inhale  flour  dust,  but  as  this 
substance  is  probably  arrested  in  the  mouth  and  nose,  and  does 
not  reach  the  lungs,  it  can  hardly  be  regarded  as  productive  of 
lung  disease.  Carpenters,  joiners,  and  cabinet  makers  are  exposed 
to  wood  dust.  The  dust  from  the  harder  kinds  of  wood  is  prob- 
ably more  injurious  than  that  from  the  softer  kinds. 

Dr.  Birmingham  has  drawn  attention  to  the  great  mortality 
among  those  engaged  in  the  "  ganister  "  industry.  Ganister  is 
a  very  hard  siHcious  stone,  with  a  very  high  fire-resisting  capacity, 
and  it  is  used  for  lining  the  bottoms  of  crucibles,  etc.  Formerly, 
a  very  large  proportion  of  the  workers  died  from  fibroid  phthisis. 

Millstone  masons  also  suffer  largely,  the  phthisis  death-rate 
of  these  workers  being  nearly  ten  times  as  great  as  that  among 
the  general  male  population  of  corresponding  ages. 

Occupational   deafness  is   most   in   evidence   among  persons 

13 


ig4  HYGIENE   AND    PUBLIC   HEALTH 

employed  as  boiler  makers,  owing  to  the  loud  hammering  which 
is  maintained.  Where  the  noises  are  very  great  and  continuous, 
workmen  are  recommended  to  plug  the  ears  with  plasticine 
worked  into  cotton. 

From  brickfields,  organic  vapours  and  CO2,  CO,  H.,S,  and  S0.> 
gases  are  evolved.  Bricks  are  made  of  clay  mixed  with  a  small 
proportion  of  ashes.  When  bricks  are  arranged  in  the  clamps  in 
layers,  alternating  with  the  breeze  or  combustible  material,  the 
emanations  from  the  burning  material  are  very  penetrating; 
and  when  dust-bin  refuse  is  used  to  burn  the  bricks,  the  partially 
burnt  organic  vapours  are  highly  disagreeable,  and  are  perceptible 
at  considerable  distances  from  the  brickfields,  ^^'hen  bricks  are 
burnt  in  kilns  provided  with  flues,  there  is  far  less  liability  to 
nuisance,  as  the  products  of  combustion  are  more  perfectly 
consumed.  Kiln  burning  should  be  insisted  upon  in  the 
case  of  all  brickfields  situated  in  the  close  vicinity  of  inhabited 
houses. 

The  Alkali  Works,  etc.,  Regulation  Act  of  1881  provides  that 
95  per  cent,  of  the  hydrochloric  acid  gases  and  vapours  produced 
in  alkali  works  must  be  condensed;  and  in  each  cubic  foot  of 
air,  gas,  or  smoke  escaping  into  the  atmosphere  there  may  be 
only  \  grain  of  HCl.  Each  cubic  foot  of  air,  gas,  or  smoke  issuing 
from  sulphuric  acid  works  must  not  contain  acidity  amounting 
to  more  than  4  grains  of  sulphuric  acid  (SO3).  The  keeping 
apart  of  acid  drainage  and  alkali  waste  is  strictly  enforced,  and 
all  waste  substances  must  be  got  rid  of  without  nuisance.  Other 
works  to  which  this  Act  applies  are  salt  works,  cement  works, 
chemical  manure  works,  nitric  acid  works,  sulphate  and  chloride 
of  ammonia  works,  chlorine  works,  bleaching  works,  and  gas 
liquor  works. 

In  the  manufacture  of  alkali  the  chief  nuisance  arises  from  the 
improper  storage  and  disposal  of  the  "  tank  waste,"  which  con- 
tains compounds  of  sulphur.  In  the  process,  common  salt  is 
decomposed  by  sulphuric  acid,  and  the  crude  sodium  sulphate 
("  salt  cake  ")  is  mixed  with  chalk  and  coal  and  heated;  sodium 
carbonate  is  thus  formed,  and  the  unburnt  carbon  and  calcium 
sulphide  darkens  the  mass,  which  is  known  as  "  black  ash." 
The  sodium  carbonate  is  dissolved  out  by  water,  and  the  residue 
constitutes  the  "  tank  waste."  The  workers  suffer  from  diseases 
of  the  lungs,  bad  teeth,  and  dyspepsia,  mainly  arising  from  the 
acid  fumes  of  the  salt  cake;  but  the  hydrochloric  acid  fumes  are 


AIR    AND   VENTILATION  ig5 

SO  diluted  as  to  generally  produce  but  little  eiiect  on  the  workers, 
though  they  injure  surrounding  vegetation. 

The  process  of  the  manufacture  of  coal  gas  varies  somewhat 
in  different  manufactories.  The  waste  gas  hme,  containing  the 
poisonous  calcium  cyanide  in  addition  to  sulphur  compounds, 
gives  rise  to  serious  offence,  and  its  removal  from  the  tank  causes 
considerable  irritation  to  those  engaged  in  the  work.  To  prevent 
dust,  the  lime  should  be  watered  a  little  before  being  dug  out 
from  the  purifiers,  and  removed  as  often  as  necessary.  During 
removal  it  should  be  covered  over  with  sacking. 

Nuisance  may  result  in  the  neighbourhood  of  gas-works  by 
(i)  smoke  given  off  during  the  charging  and  drawing  of  retorts; 
(2)  the  generation  of  water-gas  and  steam  when  the  red  hot  coke 
is  quenched  with  water,  the  steam  being  especially  offensive 
when  the  coal  used  in  the  manufacture  of  the  gas  is  of  a  sulphurous 
nature;  (3)  the  escape  of  crude  gas  from  the  mouthpieces  of  the 
retorts;  (4)  the  smoke  given  off  from  imperfectly  carbonized 
charges  when  withdrawn;  (5)  the  offensive  lime  refuse  from  the 
purifiers,  where  lime  alone  is  used  for  the  absorption  both  of 
carbonic  acid  and  sulphur  compounds.  When  exposed  to  the  air, 
sulphuretted  hydrogen  and  bisulphide  of  carbon  are  released  from 
the  sulphides  and  sulpho-carbonates  of  lime  by  the  action  of  the 
oxygen  and  carbonic  acid  in  the  air,  and  a  most  offensive  nuisance 
is  created.  When,  however,  ^esquioxide  of  iron  is  used  for 
removing  the  sulphur  compounds,  and  the  lime  is  used  only  for 
absorbing  carbonic  acid  after  the  sulphur  compounds  are  with- 
drawn, the  nuisance  is  reduced  to  a  minimum. 

Offensive  Trades. 

The  noxious  oy  offensive  trades  specified  in  the  Public  JLealth  Act,iS75, 
are  those  of  a  blood  boiler,  a  bone  boiler,  a  tripe  boiler,  a  soap  boiler,  a 
tallow  melter,  and  a  fcllmonger.  Bye-laws  may  be  made  regulating  these 
trades  "or  any  other  noxious  or  offensive  trade."  The  model  bye-laws 
of  the  Local  Government  Board  also  specify  the  trades  of  a  blood  dryer, 
a  leather  dresser,  a  tanner,  a  fat  melter  or  fat  extractor,  a  glue  and  size 
maker,  and  a  gut  scraper.  As  to  what  will  constitute  "a  noxious  or 
offensive  trade  "  other  than  those  specified,  it  is  held  that  the  business, 
in  addition  to  being  proved  noxious,  must  be  ejusdem  generis  with  those 
specified,  and  deal  with  animal  matters  in  some  form.  Thus,  brick  making 
has  been  held  not  to  be  an  "  offensive  trade,"  whereas  the  business  of  a 
rag  and  bone  merchant  is  so. 

A  BLOOD  BOILER  OR  BLOOD  DRYER  dcals  with  tlic  Iresli  blood  collected 
at  slaughter  houses,  in  order  to  procure  (i)  blood  albumin,  by  desiccating 
the  scrum  which  is  drained  off  from  the  clots;  (2)  turkey-red  pigment  ; 
and  he  may  also  (3)  prepare  blood  for  sugar  refiners,  etc.     The  blood  clot 


196  HYGIENE   AND    PUBLIC   HEALTH 

is  often  mixed  with  sulphuric  acid,  desiccated,  and  mixed  with  super- 
phosphate to  form  manure. 

The  chief  sources  of  nuisance  are  :  (i)  Unsuitability  of  premises  for 
carrying  on  the  process,  tlius  rendering  it  difficult  to  conduct  the  business 
without  nuisance;  (2)  the  improper  convej'ance  and  storage  of  the  blood; 

(3)  offensive  vapours  given  off  during  the  process  of  blood  boiling  or  drying, 
or    manure  making   (wliich  is  often  carried  on  on  the  same  premises) ; 

(4)  eflluvia  from  the  storage  of  exfiausted  clots  prior  to  the  manufacture 
of  manure  or  their  removal  from  the  premises. 

A  BONE  BOILER  deals  with  fresli  bones  in  order  to  procure  gelatine,  glue, 
and  fat.  The  bones  are  boiled  along  with  the  hoofs,  trimmings  of  hide,  etc., 
procured  from  the  slaughter  houses.  The  boiled  bones  are  subsequently 
used  for  handles  to  knives  and  forks,  tooth  brushes,  etc.,  or  are  crushed, 
and  superphosphate  manure  manufactured  from  them  by  adding  sulphuric 
acid. 

T/ie  chief  sources  of  nuisance  arise  from  :  (i)  Unsuitability  of  premises; 
(2)  improper  conveyance  and  storage  of  old  bones  and  scraps;  (3)  offensive 
vapours  given  off  dming  the  process,  especially  where  steam  jacketed 
cylinders  are  not  used  for  the  boiling;  (4)  the  debris  in  tlie  boiling  cylinder, 
called  "  the  scrutch,"  is  a  fruitful  source  of  nuisance,  as  is  also  the  piling 
u])  of  the  recently  boiled  and  steaming  bones. 

A  TRIPE  BOILER  is  One  who  boils  the  first  stomach  ("  the  paunch  ")  of 
oxen  and  sheep  for  sale  as  food. 

The  chief  nuisances  result  from:  (i)  Filthiness  and  unsuitability  of 
premises;  (2)  improper  storage  of  material  on  premises;  (3)  the  vapours 
escaping  during  the  process  of  boiling;  (4)  the  vapours  arising  from  the 
steaming  tripe  after  its  removal  from  the  boiler. 

A  FAT  OR  TALLOW  MELTER  (and  SOAP  BOILER)  is  onc  who  melts  kitchen 
fat  and  butcher's  waste  fat  in  pans  for  the  purposes  of  manufacturing 
candles,  soaps,  leather  dressings,  and  preparations  for  greasing  macliinery. 
In  soap  boiling  the  fat  is  boiled  with  soda  lye  for  "  hard  soaps,"  and  with 
potash  lye  for  "  soft  soaps." 

The  chief  nuisances  result  from  :  (i)  Filthiness  and  unsuitability  of 
premises;  (2)  improper  conveyanc  •  and  storage  of  material;  (3)  the 
vapours  escaping  during  the  process  of  melting  or  boiling,  and  ladling 
out;  (4)  the  improper  storage  of  waste  residue  ("the  greaves").  Tlie 
greatest  nuisance  during  melting  arises  when  old  and  offensive  materials 
are  used. 

A  FELLMONGER  is  One  wlio  prepares  either  recent  or  old  foreign  skins  for 
the  leather  dresser.  The  fresh  skins  are  first  trimmed  of  adherent  flesh 
and  then  freed  from  dirt  by  beating  them  with  sticks.  They  are  then 
soaked  in  water.  Lime  is  next  worked  into  the  fleshy  side  of  the  skin,  and 
the  skin  is  then  hung  up  until  the  wool  or  hair  is  easily  detachable  by  the 
hand.  The  old  foreign  skins  are  prepared  by  first  soaking  in  water,  and 
then  they  are  kept  until  decomposition  has  so  loosened  the  wool  or  hair 
that  it  is  easily  detached;  this  is  known  as  "  the  tainting  process."  By 
either  method  the  skin  thus  ])repared  is  known  as  "  a  pelt,"  and  these  are 
cast  into  a  pit  containing  milk  of  lime,  after  which  they  are  dried  and  sent 
to  the  leather  dresser. 

TJie  chief  nuisances  arise  from:  (i)  Filthiness  and  unsuitability  of 
premises;  (2)  improper  conveyance  and  storage  of  skins;  (3)  offence  arising 
from  the  "tainting"  process;  (4)  the  failure  to  satisfactorily  dispose  of 
the  dirt  and  llesh  removed  from  the  skins. 

A  LEATHER  DRESSER  and  TANNER  coiivcrt  tlic  skius,  after  treatment  as 
above  described,  into  various  kinds  of  leather.  The  tanning  agent  (oak 
bark,  etc.)  brings  the  putrescible  hide  into  a  non-putrcscible  condition: 
and  the  leather  dresser,  by  appropriate  treatment  with  fatty  and  other 
matters,  completes  the  conversion  to  leathers  of  various  sorts.     Pigeons' 


AIR    AND   VENTILATION  I97 

manure  and  dogs'  dnng  arc  iisod  in  the  "  soaks  "  for  softening  the  skins 
prior  to  tanning. 

TJw  chief  nuisances  arise  from  :  (i)  Filthiness  and  unsuitability  of 
premises;  (2)  improper  storage  of  skins;  (3)  the  failure  to  satisfactorily 
dispose  of  the  waste  water  or  spent  liquor,  etc. 

A  GUT  SCR.APER  is  one  who  scrapes  the  small  intestines  of  swine  and  sheep 
for  the  purpose  of  making  sausage  skins,  catgut,  etc.  The  gut  is  first 
cleansed  and  soaked  in  salt  and  water  for  a  few  days,  and  then  allowed  to 
remain  in  plain  cold  water  until  sufficiently  softened  to  admit  of  the  easy 
removal  (by  means  of  a  wedge-shaped  piece  of  wood)  of  everything  but  the 
peritoneal  and  a  little  of  the  external  muscular  coat  of  the  intestine. 

The  chief  tiiiisanccs  arise  from:  (i)  Filthiness  and  unsuitability  of  premises; 

(2)  the  failure  to  promptly  remove  all  refuse  and  waste  material;  (3)  im- 
proper and  too  prolonged  storage  of  the  intestines  prior  to  their  utilization. 

A  GLUE  AND  SIZE  M.^iKER  extracts  the  gelatine  by  boiling  almost  every 
kind  of  waste  animal  tissue,  but  more  especially  bones,  hoofs,  horns,  and 
skin  trimmings.  The  raw  material  is  first  limed,  and  then  washed  and 
well  boiled  for  some  hours.  After  the  glue  has  been  allowed  to  cool  and 
set,  it  is  cut  into  slices  and  dried. 

TJw  chief  sources  of  nuisance  are  :  (i)  Unsuitability  and  general  filthiness 
of  premises;    (2)  the  storage  of  material,  especially  when  old  and  foul; 

(3)  vapours  arising  from  the  conduct  of  the  process,  which  are  especially 
offensive  when  old  material  is  used ;  (4)  the  accumulation  and  improper 
storage  of  the  residue  ("scrutch").  The  fat  is  usually  skimmed  off  the 
surface  of  the  hot  water,  and  the  "  scrutch  "  is  used  for  manure  making. 

The  various  nuisances  in  the  trades  above  referred  to  may  be  prevented 
or  abated  by  the  adoption  and  enforcement  of  sufficient  bye-laws. 
Such  bye-laws  should  secure : — ■ 

1.  Free  access  to  the  premises  by  any  officer  of  the  sanitary  authority, 

2.  The  restriction  of  such  trades  to  suitable  premises.  Gut  scraping, 
for  instance,  cannot  be  carried  on,  as  it  sometimes  is,  in  small  houses, 
without  giving  rise  to  offence. 

3.  The  maintenance  in  good  order  of  the  drainage,  lighting,  and  ventila- 
tion of  such  premises,  and  the  proper  cleansing  of  them.  The  floors  or 
pavements  should  be  kept  in  good  repair  so  as  to  prevent  absorption  of 
any  liquid  filth,  and  should  be  swept  or  washed  at  the  close  of  every  day, 
and  all  splashings  should  be  removed.  The  walls  and  ceilings  should  be  hot 
limewashed  twice  a  year  at  specified  periods  (say  the  first  weeks  of  April 
and  October),  after  all  splashings  have  been  wiped  off;  and  the  walls 
must  be  rendered  non-absorbent  of  any  liquid  filth  or  refuse  to  at  least  the 
height  to  which  such  splashings  may  reach. 

4.  The  proper  conveyance  to  the  premises,  and  storage  on  the  premises 
of  the  material  used,  so  as  to  prevent  the  escape  of  noxious  and  offensive 
emanations.  In  some  cases  the  material  should  be  brought  to  the  premises 
in  non-absorbent  covered  receptacles,  and  stored  in  special  closed  compart- 
ments ventilated  into  a  tall  chimney  flue,  by  means  of  an  air  shaft  provided, 
if  necessary,  with  a  gas  jet  or  fan.  Sometimes  the  materials  to  be  stored 
should  be  dried,  or  treated  with  milk  of  lime,  or  even  sprinkled  with  a 
little  carbolic  acid  solution  (i  in  40).  Stored  fat  should  be  dried  and  laid 
out  on  racks  in  a  cool  room;  and  the  materials  used  for  glue  making 
should  be  stored  as  dry  as  practicable,  or  treated  with  a  sufficient  quantity 
of  milk  of  lime  and  closely  stacked. 

5.  The  best  practical  means  of  rendering  inert  the  vapours  emitted  during 
the  carrying  on  of  the  process.  Where  melting  and  boiling  is  performed, 
this  should  be  done  in  steam  jacketed  pans,  so  as  to  guard  against  the 
higher  temperatures  which  burn  the  fat,  etc.,  and  give  rise  to  the  formation 
of  most  offensive  emp\Teumatic  odours.  Large  hoods  commimicating 
by  pipes  with  the  furnace  flue  should  be  used  to  collect  the  vapours  given 


198  HYGIENE   AND    PUBLIC   HEALTH 

off  from  the  contents  of  the  pans  dnring  the  boiling;  and  the  chimney  by 
which  these  fumes  escape  should  either  be  carried  up  to  a  considerable 
height,  or  the  vapours  should  be  condensed  in  a  suitable  condensing 
apparatus,!  or  conducted  into  the  firrnace  fire  and  cremated.  This 
cremation  maj^  also  be  effected  by  means  of  a  small  "  cremator  "  placed  in 
the  chimney. 

The  fumes  arising  from  steaming  bones,  meat,  etc.,  can  be  prevented  by 
applying  cold  water,  directly  after  their  removal  from  the  boiler. 

6.  All  filth  and  refuse  matter  to  be  collected  in  a  sufficient  number 
of  non-absorbent  vessels  with  close-fitting  covers,  and  removed  from  the 
premises  forthwith.  Fellmongers  and  others  must  not  keep  uselessly' 
decomposed  skins,  etc.,  on  the  premises. 

7.  All  water  used  for  soaking  skins,  etc.,  to  be  removed  sufficiently  often 
(at  least  once  a  day)  to  prevent  effluvia  arising  therefrom,  and  all  pits  used 
for  holding  such  water  to  be  rendered  water-tight.  This  bye-law  will  apply 
to  the  trades  of  a  fellmonger,  gut  scraper,  and  leather  dresser. 

8.  All  waste  lime  to  be  removed  with  reasonable  dispatch  in  covered 
receptacles,  as  also  all  other  wastes  or  useless  material. 

9.  All  implements  and  receptacles  to  be  kept  sweet  and  clean.  The 
floors  and  receptacles  in  some  cases  to  be  sprinkled  or  washed  with  some 
deodorant,  as  in  gut  scraping. 

10.  Penalties  for  offending. 

The  discharge  of  waste  liquor  into  drains  at  a  temperature  exceeding 
1 10°  F.  has  often  given  rise  to  great  offence  from  the  sewer  ventilators 
adjoining  the  premises  on  which  some  of  the  above  trades  are  conducted. 
This  is  now  provided  for  by  statute  (The  Public  Health  Act  Amendment 
Act,  1890),  and  all  hot  liquid  refuse  must  be  allowed  to  cool  before  it  is 
discharged  into  a  drain. 

It  will  be  well  to  next  consider  a  few  of  the  more  common  trade  nuisances. 

Fish  frying. — Nuisances  arise  from  the  neglect  to  adopt  proper  means 
of  collecting  the  effluvia  and  dealing  efficiently  with  them .  The  effluvia  are 
increased  bj'  (i)  the  prolonged  use  of  the  same  oil  for  cooking  purposes, 
(2)  the  burning  of  the  oil  and  consequent  production  of  empyreumatic 
odours,  when  the  heating  is  done  over  an  open  fire. 

These  nuisances  are  best  prevented  by  using  the  best  dripping  instead  of 
oil,  and  by  supplying  a  large  deep  hood  to  collect  the  effluvia  arising  from 
the  frying.  The  hood  should  lead  by  a  shaft  into  a  fairly  high  chimney, 
and  it  is  often  necessary  to  provide  a  gas  jet  at  the  mouth  of  the  shaft 
eading  from  the  hood,  so  as  to  promote  draught.  To  obviate  the  burning 
of  the  oil,  the  frying  should  be  done  in  a  deep  vessel  containing  from  6  to 
in  inches  in  depth  of  oil,  or  jireferably  steana  jacketed  cylinders  should  be 
employed.  It  is  rarely,  if  ever,  necessary  to  cremate  the  effluvia  in  the 
fire,  or  to  absorb  them  in  the  water  of  a  "  washer  "  or  condenser. 

Knackeries.- — A  knacker  is  properly  a  horse  slaughterer,  but  he  also 
slaughters  other  old  and  diseased  animals,  and  receives  the  carcases  of 
those  which  have  died  of  disease  or  accident. 

Nuisances  arise  from  the  cries  of  the  animals  prior  to  their  slaugliter, 
for  they  are  commonly  kept  several  days ;  the  filth}'  way  in  which  they 
are  sometimes  kept;  the  undue  and  improper  storage  of  material  on  the 
premises ;  the  general  unsuitability  and  filthiness  of  the  premises ;  and 
the  processes  of  bone  boiling,  flesh  boiling  (for  cats'  meat  or  fat  extraction), 
or  gut  scraping,  etc.,  which  are  sometimes  carried  on  in  the  same  premises. 

1  A  cheap  and  satisfactory  condenser  can  be  made  by  taking  ordinary 
drain  pipes  and  packing  them  with  pieces  of  coke,  over  which  water  is 
allowed  to  trickle  in  a  constant  stream;  or  the  vapours  may  be  absorbed 
in  a  water  spray,  or  b\^  being  brought  in  contact  with  trays  of  water,  as 
in  a  "  scrubber." 


AIR    AND    VENTILATION  I99 

Pig  keeping. — This  trade  may  become  a  nuisance  from  the  improper 
storasi;e  of  sour,  malodorous  food,  witli  which  tlie  pif^s  are  frequently  fed, 
and  from  the  el'lluvia  from  the  sties.  The  sties  should  always  be  placed 
at  a  considerable  distance  frf)m  houses — at  least  100  feet  in  urban  districts. 
They  should  be  floored  with  hard,  impervious,  and  jointless  material  (e.g., 
concrete),  laid  to  a  good  fall  towards  a  channel  leading  to  a  galley  which 
discharges  into  a  drain  or  covered  cesspool.  The  feeding  material  should 
be  kept  in  impervious  vessels  with  close  fitting  lids,  and  the  sties  should 
be  swept  out  and  cleansed  daily. 

Artificial  manure  making. — The  materials  used  are:  (i)  All  animal 
waste  materials  from  the  ofl[ensive  trades  above  referred  to;  (2)  mineral 
matter,  e.g.,  sulphate  of  ammonia,  nitrate  of  soda,  gypsum,  etc. 

"  Superphosphate  "  is  made  from  a  mixture  of  mineral  phosphate  and 
ground  bones,  treated  with  sulphuric  acid.  The  whole  process  is  more  or 
less  offensive  from  the  presence  of  the  organic  materials,  and  the  fumes 
given  off  during  the  manufacture  and  the  subsequent  drying. 

"  Poudrette  "  is  generally  manufactured  from  privy  or  pail  contents, 
fish  ofEal,  etc.,  by  treatment  with  sulphuric  acid;  it  consists  of  a  brown 
dry  powder.  The  process  must  be  conducted  under  very  special  conditions, 
or  a  grave  nuisance  results. 

Paper  making. — Cotton  and  linen  rags,  wood  pulp,  hemp,  straw,  waste 
paper,  etc.,  and  esparto  grass  are  employed  in  this  business.  The  rags  are 
"  dusted,"  and  then  placed  in  boilers  to  which  caustic  soda  is  added.  After 
the  rags  have  been  well  lioiled,  the  liquid  shoidd  be  run  into  settling  tanks, 
and  subsequently  filtered  through  earth  and  ashes,  before  it  is  permitted 
to  enter  a  stream,  so  as  to  obviate  serious  pollution  and  nuisance.  When 
the  rags  are  removed  from  the  boilers  they  are  washed,  and  bleached. 

Esparto  grass  is  reduced  to  pulp  by  boiling  with  caustic  alkali  and  by 
subsequent  treatment  by  machinery. 

The  vapours  given  off  during  the  boiling  of  the  grass,  and  from  the  hot 
liquor  after  removal  from  the  boilers,  have  an  offensive  senna-like  odour, 
but  the  recovery  of  the  soda  from  the  waste  liquor  is  the  most  offensive 
part  of  the  process. 

Industrial  Poisonings. 

Lead  poisoning  may  result  from  direct  absorption  of  the  metal  through 
the  skin  or  mucous  membranes,  or  by  inhalation  of  the  vapours  or  powder 
of  lead  compounds.  The  trades  most  liable  to  suffer  are  :  painters, 
plumbers,  pottery  workers,  gilders,  file  cutters,  type  founders,  calico 
printers,  glass  grinders,  bronzers,  enamellers,  and  the  manufacturers  of 
white  lead  and  lead  paints  and  colours. 

Carbonate  of  lead,  or  white  lead,  is  very  extensively  used  as  a  paint,  and 
many  coloured  paints  contain  the  metal.  Both  the  acetate  and  the  nitrate 
of  lead  are  used  in  calico  printing  and  cotton  dyeing  to  produce  orange  and 
yellow  colours.  Sulphide  of  lead  is  used  mainly  for  glazing  pottery, 
bricks,  etc.,  and  oxide  of  lead  is  used  in  enamels. 

File  makers  are  liable  to  lead  poisoning  from  their  using  a  cushion  of 
lead  on  which  to  rest  the  file  while  the  rough  surface  is  being  prepared  by 
means  of  a  blunt  chisel  struck  with  a  hammer.  The  glass  grinders  may 
be  poisoned  from  the  constant  contact  with  the  putty  powders  (rich  in 
lead)  which  are  used  for  polishing  the  glass ;  and  the  type  founders  and 
type  setters  from  the  constant  handling  of  the  type  metal — an  alloy  of 
lead,  tin,  and  antimony. 

At  present  the  most  common  causes  of  lead  poisoning  are  the  working 
with  lead  glazes,  and  the  manufacture  of  white  lead.  "The  proportion 
of  severe  cases  among  file  cutters  and  those  engaged  in  coach  painting,  in 
ship  building,  and  in  other  industries  where  paint  is  used,  exceeds  that  of 
those  engaged  in  industries  where  the  danger  is  primarily  from  the  dust 


200  HYGIENE   AND    PUBLIC   HEALTH 

of  salts  of  lead  "  (T.  M.  Legge,  H.M.  Medical  Inspector  of  Factories). 
Plumbers  inhale  volatilized  oxide  of  lead  and  painters  the  dust  of  white 
lead ;  but  lead  is  also  taken  into  the  system  when  meals  are  taken  with 
dirty  hands. 

Sanitary  Precantiotis.- — i.  All  fumes  and  dust  should  be  collected  as 
rapidly  and  completely  as  possible  as  the}^  are  formed,  and  conducted, 
by  means  of  a  powerful  exhaust,  to  condensing  chambers  or  washers;  so 
that  the  air  of  the  work  places  may  be  kept  as  pure  as  possible,  and  the 
external  atmosphere  around  the  works  also  saved  from  pollution. 

2.  The  handling  of  the  metal,  or  of  substances  containing  lead,  should 
be  reduced  to  a  minimum. 

3.  Every  facility  and  encouragement  should  be  given  to  the  workers 
to  practise  personal  cleanliness.  Mouth  washes  and  tooth  and  nail  brushes 
should  be  used  before  partaking  of  a  meal.  Strict  rules  should  be  enforced 
for  the  washing  of  hands.  A  basin,  tap,  and  towels  must  be  supplied  lor 
at  most  every  five  persons. 

4.  In  the  more  dusty  rooms  overalls,  close  fitting  roimd  the  neck  and 
wrists,  and  respirators  are  desirable,  in  addition  to  exhaust  fans  to  remove 
dust  and  insure  abundance  of  fresh  air. 

5.  Meals  should  not  be  permitted  to  be  taken  in  any  of  the  work- 
rooms. 

6.  There  should  be  periodical  medical  inspection  of  the  workers.  Those 
who  are  more  especially  susceptible  to  the  poisonous  effects  of  the  metal 
should  at  least  be  excluded  from  the  more  dangerous  rooms.  This  will 
apply  to  all  women  and  children.  All  those  with  cuts  or  sores  should  be 
excluded  from  the  works. 

7.  Sulphuric  acid  lemonade  is  recommended  as  a  drink  for  the  work- 
people, as  it  favours  the  formation  of  an  insoluble  sulpliate  of  lead;  the 
free  drinking  of  milk  is  also  recommended. 

8.  The  workrooms  must  be  kept  clean,  well  ventilated,  and  as  free 
from  dust  as  possible.  The  immediate  removal  of  the  dust  is  the  essential 
preventive  measure  in  china  and  earthenware  factories,  in  places  where 
processes  connected  with  white  and  red  lead  are  carried  on,  in  paint  and 
colour  factories,  in  all  workrooms  in  which  operations  of  litho-transfer 
are  conducted,  and  wherever  iron  plates  are  enamelled. 

By  the  adoption  of  preventive  measures  on  these  lines,  cases  of  industrial 
lead  poisoning  in  this  country  have  been  reduced  some  50  per  cent,  during 
the  past  few  years. 

The  beautiful  glaze  on  chinaware  and  its  colouring  have  hitherto  been 
mostly  obtained  by  the  use  of  carbonate  of  lead,  and  the  workers  in  these 
processes  suffer  considerably  from  lead  poisoning.  The  use  of  "  fritted  " 
lead — that  is,  lead  fused  into  a  kind  of  glass  (a  silicate)  which  is  ground 
down  and  mixed  with  water— is  attended  with  far  less  danger  to  the 
workers.  It  is  stated  that  it  is  even  safer  to  employ  a  double  silicate  of 
lead,  which  is  more  insoluble  than  the  silicate.  It  appears,  moreover,  that 
the  use  of  leadless  glazes  gives  equally  satisfactory  results  in  ordinary 
white  and  cream-coloured  ware;  and  experts  have  expressed  the  view 
that  for  seven-tenths  of  the  total  output  leadless  glazes  can  be  used.  No 
glaze  can  now  be  used  which  yields  to  a  dilute  solution  of  hydrochloric  acid 
(0-25  percent,  of  acid,  the  same  acidity  as  that  of  human  gastric  juice)  more 
than  5  per  cent,  of  its  dry  weight  of  soluble  lead,  calculated  as  lead  mon- 
oxide. Higher  percentages  of  lead  are  allowed  on  condition  that  the 
employer  adopts  a  scheme  of  compensation  for  those  of  his  workpeople 
who  suffer  from  lead  poisoning,  such  workpeople  being  aware  of  the  risks 
they  run,  and  agreeing  to  face  such  risks. 

PiiosPTioRTTs  POISONING  is  experienced  among  match  makers.  Makers 
of  phosphor-bronze  and  the  old-time  vermin  killer  have  also  suffered.  The 
phosphorus  is  obtained  from  bone  ash,  and  serious  nuisance  and  harm  to 


AIR    AND   VENTILATION  201 

the  workers  will  result  unless  every  proper  precaution  is  taken.  During 
the  distillation  of  the  impure  phosjihorus,  dangerous  gases  are  evolved. 

The  red  or  amorphous  phosphorus  is  largely  used  in  the  manufacture 
of  safety  matches,  the  phosphorus  mixed  with  glue  being  contained  in  the 
rubbing  surface  on  the  box.  The  igniting  material  is  composed  of  chlorate 
of  potash,  iron  pyrites,  peroxide  of  manganese,  powdered  glass,  sul}>hide 
of  antimony,  and  an  adhesive  agent — ^generally  glue. 

San  itary  Precautions. —  i .  The  discontinuance  of  the  use  of  the  dangerous 
yellow  phosphorus,  which  is  volatile  at  ordinary  temperatures,  and  the 
employment  of  the  red  phosphorus  for  safety  matches  only.  A  harmless 
"  strike  everywhere  "  match  can  now  be  made  from  the  sesquisulphide  of 
phosphorus. 

2.  Frequent  medical  inspection,  especially  of  the  teeth.  It  is  found  that 
workers  with  sound  teeth  are  practically  exempt,  but  workers  with  carious 
teeth  are  specialh-  prone  to  poisoning  iDy  phosphorus  and  to  the  onset  of 
"  phossy  jaw  "  (caries  of  the  jaw  bones). 

3.  The  selection  of  the  workers. 

4.  Ever}'  facility  for  the  practice  of  extreme  personal  cleanliness. 
Allcaline  mouth  washes  should  be  used. 

5.  Large,  specially  well  ventilated  workrooms,  and  when  possible  the 
work  should  be  performed  in  the  open  air.  This  precaution  greatly 
reduces  the  amount  of  phosphorus  poisoning.  All  fumes  should  be  drawn 
away  from  the  worker  by  means  of  efficient  extraction  fans. 

6.  No  food  or  drink  to  be  taken  in  the  workrooms. 

7.  Short  shifts  of  work,  especially  of  those  employed  in  the  more  dan- 
gerous rooms.  Charcoal  respirators  should  be  worn  by  those  engaged 
in  the  worst  rooms;  i.e.,  where  the  dipping  of  the  wooden  heads  of  the 
matches  in  the  phosphorus  paste  is  performed. 

8.  The  emplo^yTnent  of  machinery  for  dipping,  drying,  and  boxing 
matches,  as  now  installed  in  some  manufactories. 

The  most  dangerous  factor  in  the  whole  process  is  the  escape  of  fumes 
of  the  lower  oxide  of  phosphorus  (P40g)  from  the  moist  heated  paste. 

The  oxidizing  efEect  of  the  vapour  of  turpentine  is  recommended  as 
advantageous.  The  atmosphere  may  be  impregnated  with  these  vapours 
by  exposing  turpentine  in  saucers  about  the  room,  or  on  sponges  hung 
round  the  necks  of  the  workers,  so  that  the  vapours  rise  up  into  the  air 
as  it  is  respired. 

The  phosphorus  should  always  be  stored  carefully  in  glass  or  earthenware 
vessels  surrounded  by  water,  and  away  from  the  workrooms. 

The  sulphur  employed  must  not  be  overheated,  or  there  is  danger  of 
ignition  and  the  development  of  large  quantities  of  SO2.  The  pans  in 
which  the  sulphuring  is  done  should  be  covered,  and  the  fumes  conducted 
to  a  tall  chimnej-. 

Owing  to  the  adoption  of  greater  sanitary  precautions,  only  one  case 
of  phosphorus  necrosis  has  been  reported  for  several  years. 

The  .  ymptoms  of  chronic  phosphorus  poisoning  are  anaemia,  anorexia, 
headache,  emaciation,  cutaneous  and  muscular  hyper a2Sthesia,  muscular 
pains  and  weakness.  In  those  exposed  to  fumes,  there  may  occur  pain  and 
swelling  of  the  gums,  followed  by  abscess  and,  later,  necrosis  of  the  jaw 
bone  ("  phosry  jaw  ").  Persons  exposed  to  phosphorus  fumes  are  said 
to  be  liable  to  bronchitis  and  to  spontaneous  fracture  of  the  long  bones. 

As  to  the  causation  of  chronic  phosphorus  poisoning  the  most  probable 
theory  (Lorinser)  appears  to  be  that  the  blood  becomes  surcharged  with 
phosphorus,  which  in  turn  has  a  special  affinity  for  bone,  and  as  a  conse- 
quence weakens  the  resistance  of  that  tissue  to  local  injury — this  local 
injury  in  the  case  of  the  jaw  bone  being  supplied  through  the  medium  of  a 
carious  tooth.  Such  necroses  occur  only  after  the  worker  has  been  for 
some  years  engaged  in  the  work,  and  the  necessary'  constitutional  changes 


202  PIYGIENE    AND    PUBLIC    HEALTH 

have  been  induced.  By  an  order  of  the  Secretary  of  State  in  1809,  cases 
of  phosphorus  poisoning  must  be  notified  under  the  Factory  and  Workshop 
Act,  1895. 

Mercurial  poisoning. — Those  exposed  to  the  poisonous  effects  of 
the  vapours  are  mainly  the  makers  and  users  of  vermiUon  pigment  from 
cinnabar  and  of  imitation  bronzing,  barometer  and  thermometer  makers, 
and  the  gilders  working  with  mercurial  gold  amalgam.  The  former 
great  source  of  industrial  mercurial  poisoning — the  silvering  of  mirrors 
by  means  of  an  amalgam  of  mercury  and  tin — has  ceased,  the  process 
having  been  superseded  in  this  country  by  the  nitrate  of  silver  and 
ammonia  process.  The  workers  in  factories  where  calomel,  corrosive 
sublimate,  and  the  red  oxide  of  mercury  are  prepared,  hatters,  furriers, 
and  the  makers  of  electric  meters  and  electric  lamps,  also  suffer.  Furriers 
brush  the  fur  with  a  solution  of  the  acid  nitrate  of  mercury. 

The  symptoms  of  mercurial  poisoning  are  insidious  in  their  onset.  They 
are  anaemia,  tender  gums,  often  salivation,  diarrhoea,  tremors  of  the  face, 
arms,  and  hands;  the  teeth  frequently  fall  out.  Mercurial  poisoning 
appears  to  predispose  to  phthisis,  and  to  be  piedisposed  to  by  alcoholism. 

The  sanitary  precautions  necessary  are  similar  to  those  already  indicated 
where  poisonous  fumes  and  dust  occur;  but  it  is  important  to  observe 
that  the  mercury  should  be  kept  covered  over  as  much  as  possible,  so  as 
to  limit  the  diffusion  of  the  vapours,  especially  in  hot  workshops.  The 
diffusion  of  the  vapours  of  ammonia  through lut  the  workshops  when 
these  are  temporarily  vacated,  is  highly  spoken  of.  The  floor  of  the 
workshop  should  be  such  as  to  admit  of  a  thorough  collection  of  all  spilt 
mercury  at  the  end  of  each  working  day. 

A  very  important  preventive  measure  is  care  of  the  mouth  and  teeth, 
and  the  removal  or  filling  of  carious  teeth.  All  cases  of  mercurial  poisoning 
must  be  notified  to  the  Chief  Inspector  of  Factories. 

Arsenic  poisoning  may  result  from  the  use  of  arsenical  wall  papers, 
carpets,  and  curtains,  in  which  the  arsenic  is  used  as  a  colouring  agent.  In 
the  following  trades  the  workers  are  liable  to  arsenic  poisoning :  The 
makers  of  articles  coloured  with  arsenical  dyes  (carpets,  dresses,  artificial 
flowers,  etc.);  tho.-,e  who  prepare  skins  of  animals  for  stuffing;  and  the 
makers  of  arsenical  paints  and  dyes,  such  as  "  emerald  green."  This  salt 
is  also  used  for  the  destruction  of  the  insect  pests  which  destroy  fruit  trees 
and  potatoes. 

The  sanitary  precautions  necessary  are  very  similar  to  those  which 
should  be  practised  against  lead  poisoning.  Arsenical  colours  and  dyes 
are  unnecessary,  and  their  use  should  be  prohibited.  No  water  from  the 
works  containing  waste  arsenic  should  be  allowed  to  enter  a  stream. 

Chromium  poisoning. — Chrome  colours  are  largely  used  by  dyers, 
chiefly  as  yellow,  orange,  and  red  colouring  agents,  but  aniline  dyes  are 
now  taking  their  place.  The  chief  symptoms  of  poisoning  (from  swallowing 
chromium)  closely  resemble  those  of  Asiatic  cholera.  The  effect  of  the 
chromates  of  potash  on  the  skin  and  mucous  membranes  exposed  to  their 
action  is  to  cause  destructive  ulceration,  the  nasal  mucous  membrane 
being  especially  liable  to  suffer  from  the  lodgment  of  the  fine  dust  resulting 
from  the  grinding  of  the  chromates. 

The  sanitary  precautions  which  are  necessary  can  be  gathered  from  what 
has  already  been  said  with  reference  to  lead. 

Various  forms  of  eczema  and  ulceration  may  be  set  up  by  irritants  used 
in  the  technical  arts  and  crafts.  Of  these,  bichromates,  aniline,  arsenic, 
materials  used  by  potters  and  laundresses.  fl;ix,  strong  alkalies,  acids,  and 
other  chemicals  are  the  most  important.  Often  the  lesions  in  the  mucous 
membranes  are  more  distressing  than  those  of  the  skin.  The  handling 
oi  tar  often  causes  eczema. 

Under  special   rules   issued   by   the    Home   Office,   periodical   medical 


AIR   AND   VENTILATION  20$ 

examination  of  workers  in  dangerous  processes,  either  by  the  certifying 
factory  surgeon  or  otiier  medical  ]iractitioner,  is  required  in  the  following 
industries:  White  lead  works,  china  and  earthenware  works,  the  manu- 
facture of  litho-transfers,  enamelling  of  iron  plates,  electrical  accumulator 
works,  the  manufacture  of  explosives  in  which  dinitro-benzol  is  used,  and 
bichromate  factories ;  in  lucifer  match  factories  where  yellow  phosphorus 
is  used  periodical  examination  of  the  teeth  of  the  persons  in  certain  specified 
processes  is  enjoined.  Further,  in  paint  and  colour  factories,  in  chemical 
works  where  pharmaceutical  mercurial  preparations  are  made,  in  hatters- 
furriers'  processes  where  mercury  nitrate  is  used,  etc.,  similar  voluntary 
periodical  examination  is  in  some  cases  provided. 

Sulphurous  acid  may  find  its  way  into  the  atmosphere  from  a  large 
number  of  industries:  The  manufacture  of  sulphuric  acid,  alum,  and 
glass,  the  tinning  of  iron,  bleaching  w.rks  of  certain  kinds  (wool,  cotton, 
sillr  straw,  etc.),  the  preparation  of  hops,  and  the  burning  of  coal  rich 
in  pyrites,  etc.     The  gas  may  give  rise  to  bronchitis  and  anaemia. 

Chlorine  may  gain  access  to  the  atmosphere  from  bleaching  and  dyeing 
works.  It  causes  acute  catarrh,  acute  pneumonia,  conjunctivitis,  pyrosis, 
and  indigestion.  Respirators  kept  moist  with  alcohol  are  recommended 
as  a  protection. 

Bisulphide  of  carbon  gets  into  the  atmosphere  of  vulcanized  india- 
rubber  works,  the  liquid  being  used  as  a  solvent  of-  gutta-percha. 

In  the  manufacture  of  Portland  Cement  traces  of  compounds  of 
cyanogen  are  given  off  during  the  process  of  burning. 

Carbonic  acid  is  given  off  in  large  quantities  from  lime  burning,  and  is 
often  present  in  excess  in  the  air  of  aerated  water  manufactories. 

It  causes  debility,  loss  of  appetite,  drowsiness,  and  nervous  derange- 
ments, and  when  present  in  great  quantities  causes  dyspnoea,  muscular 
debility,  and  coma;  and,  if  death  results,  the  heart  and  lungs  are  filled 
with  dark  blood.  Well  sinkers  are  occasionally  asphyxiated  by  the  large 
amount  of  this  gas  which  collects  in  deep  shafts. 

In  carbonic  oxide  poisoning,  on  the  other  hand,  there  is  no  dyspnoea, 
coma  is  slight  or  absent,  there  is  drowsiness  followed  by  loss  of  con- 
sciousness, convulsions  may  occur,  and  the  blood  is  bright,  with  a  bluish  tint. 

Less  than  0-3  per  cent,  of  CO  in  the  atmosphere  may  cause  unpleasant 
if  not  serious  symptoms. 

The  symptoms  of  chronic  poisoning  are  not  very  definite.  There  may 
be  headache,  sickness,  diarrhoea,  impaired  digestion,  a  dry  throat,  physical 
and  mental  depression,  and  anaemia.  Those  most  liable  to  CO  poisoning 
are  the  workers  at  coke  ovens  and  brick-kilns,  limestone  workers  and 
cement  workers,  coal  miners  after  explosions  of  fire-damp,  coal  gas  makers 
(from  escapes  of  gas),  distillers  of  coal  tar,  lamp-black  makers  and  iron 
smelters.  CO  is  also  liable  to  be  present  in  the  air  of  laimdries  where  the 
irons  are  heated  over  flueless  gas  stoves. 

Several  fatal  accidents  have  resulted  from  the  carrying  of  ferro-silicox 
as  a  cargo  on  ships  and  barges.  This  material  is  used  in  the  inanufacture 
of  certain  grades  of  steel,  and  is  an  alloy  of  iron  and  silicon.  The  low 
grade  variety,  containing  not  more  than  15  per  cent,  of  silicon,  is  made 
in  blast  furnaces  in  this  country;  while  the  high  grade  classes,  containing 
from  25  to  95  per  cent,  of  silicon,  can  only  be  made  in  the  electric  furnace, 
and  are  largely  imported  from  the  Continent.  Ferro-silicon  of  grades 
under  30  and  over  70  per  cent,  would  appear  to  be  innocuous  (Copeman), 
but  grades  between  30  and  70  per  cent,  give  off  poisonous  emanations, 
the  chief  poisonous  gas  being  phosphoretted  hydrogen,  along  with  a  small 
quantity  of  arseniuretted  hydrogen.  In  a  report  of  the  Tocal  Govern- 
ment Board  on  ferro-silicon  (1908-09),  it  is  recommended  that  only  the 
non-injurious  grades  should  be  used  in  steel  manufacture,  but  that  if 
the  injurious  grades  are  used,  they  should  be  exposed  to  the  air,   but 


204  HYGIENE   AND   PUBLIC   HEALTH 

under  cover,  for  at  least  a  month  before  transit ;  that  no  passenger  boats 
should  be  iised  to  convey  them ;  and  that  storage  places  at  docks  or  works 
should  have  free  provision  for  access  of  air,  and  should  not  be  near  work- 
rooms or  offices. 

Household  Dust. 

Besides  vitiation  by  products  of  respiration  and  combustion, 
one  great  cause  of  impurity  of  air  in  houses  is  the  presence  of 
floating  particles  of  dust.  This  dust  is  the  debris  arising  from 
the  wear  and  tear  of  articles  in  domestic  use,  mingled  with  the 
soot  and  ashes  from  lire-places,  lamps  and  gas  burners.  As  soon 
as  the  air  is  still,  it  tends  to  settle  upon  walls,  floors  and  articles 
of  furniture,  to  be  again  caught  up  and  wafted  into  the  air,  when 
this  is  in  brisk  movement.  Under  the  microscope  this  dust 
resolves  itself  into  soot,  mineral  particles  (silica,  oxide  of  iron, 
crystals  of  sodium  chloride),  cotton  fibres,  spores  of  fungi  or 
bacteria,  starch  grains,  pulverized  straw,  epithelial  and  epidermic 
debris  from  the  skin.  It  is  thus  seen  to  consist  largely  of  organic 
refuse,  sometimes  more  or  less  putrescent,  and  its  presence  in 
the  air  assists  in  the  production  of  the  low  state  of  health  so 
common  to  the  occupants  of  dirty  overcrowded  houses. 

In  all  houses  dust  must  be  produced  by  the  wear  and  tear  of 
domestic  life;  but  in  towns  this  strictly  domestic  dust  is  much 
augmented  by  that  which  finds  its  way  in  through  doors  and 
windows  from  the  outer  atmosphere.  We  cannot  hope,  then,  to 
materially  limit  its  production;  but  much  may  be  done  to  get 
rid  of  it,  and  to  prevent  its  undue  accumulation,  by  thorough 
and  regular  house  cleaning. 

House  cleaning  can  only  be  efficient  where  the  structural  con- 
ditions of  walls,  floors,  and  ceilings  permit  of  easy  access  for  the 
broom  and  duster  into  every  part  of  the  room,  and  where  furniture 
and  fittings  are  so  arranged  as  to  prevent  dust  being  deposited 
in  inaccessible  places. 

As  generally  arranged,  nearly  every  part  of  a  room  is  a  dust 
trap.  Cornices  and  projections  on  ceilings  and  above  doors; 
rough  or  flock  wall  papers;  floors  with  crevices  between  the  boards 
into  which  dust  drops,  to  gradually  accumulate  between  the  floor 
and  the  ceiling  below;  carpets  accurately  fitting  every  corner 
of  the  room;  cumbersome  articles  of  furniture,  as  wardrobes, 
sideboards,  and  bookcases,  which  collect  dust  above,  and  are 
too  heavy  to  be  moved  to  allow  dust  to  be  swcj:)t  out  below; 
heavy  curtains  with  canopies,  draperies,  etc. — all   these  tend  to 


AIR   AND   VENTILATION  205 

the  collection  of  dust,  which,  being  unseen,  is  forgotten  and  not 
removed. 

It  is  especially  in  bedrooms,  which  are  occupied  for  so  many 
hours  without  any  thorough  renewal  of  the  air,  that  these  dust 
accumulators  tend  to  do  so  much  harm,  by  contaminating  an 
atmosphere  already  vitiated.  The  following  rules,  therefore, 
although  to  be  recommended  in  every  room  of  a  house,  are  more 
especially  apphcable  to  bedrooms. 

The  floors,  if  old  and  warped,  should  be  accurately  fitted  with 
thin  oak  parqueterie,  kept  well  pohshed  with  oil  and  beeswax; 
or  the  spaces  between  the  boards  may  be  filleted — i.e.,  filled  in 
with  strips  of  wood,  so  as  to  leave  no  chinks — and  the  whole  either 
stained  or  varnished,  or  coated  with  three  or  four  good  coats  of 
paint  and  varnished.  This  flooring  can  be  kept  clean  with  a 
damp  duster.  Carpets  should  be  abohshed  in  favour  of  mats  or 
Indian  matting  for  bedrooms,  which  is  very  httle  retentive  of 
dust  and  easily  cleaned.  The  mats  can  be  frequently  shaken  and 
beaten  in  the  open  air,  whereas  fixed  carpets  are  usually  beaten 
once  a  year,  and  in  the  interval  accumulate  much  dust  (especially 
the  thick  pile  carpets).  The  use  of  linoleum  and  oilcloth  should 
be  avoided,  as  it  hinders  the  ventilation  of  the  boards,  and  tends 
to  cause  dry-rot. 

Heavy  curtains,  canopies,  and  draperies  should  be  replaced 
by  hght  mushn  fabrics  in  bedrooms,  which  can  be  washed  and 
cleaned  at  frequent  intervals.  Bedroom  furniture  should  be 
hght  and  easily  moved.  It  would  be  a  great  improvement,  if, 
when  houses  are  built,  the  bedroom  walls  were  planned  with 
recesses,  which  could  be  converted  into  cupboards,  shelves, 
and  drawers;  and  thus  the  actual  furniture  of  a  bedroom  could 
be  reduced  to  the  bed,  washstand,  dressing  table,  and  chairs, 
and  there  would  be  no  surface  on  which  dust  could  he  concealed. 

Cornices  and  projections  from  walls  and  ceiUngs  should  be 
avoided,  as  hkely  to  collect  dust. 

The  wall  coverings  should  be  smooth  and  glossy.  Rough  wall- 
papers, especially  flock  papers,  can  hold  enormous  quantities  of 
dust.  For  bedrooms  and  nurseries  distemper  colouring  is  perhaps 
better  than  waU-papers,  as  the  surface  can  be  renewed  at  a 
trifling  cost  and  at  frequent  intervals.  In  distempering,  common 
whiting  is  used  as  a  basis  for  the  colouring,  and  not  white  lead 
or  zinc  white,  as  is  almost  invariably  the  case  in  painting.  Newly 
painted  surfaces  give  off  traces  of  lead,  volatihzed  or  in  powder. 


206  HYGIENE   AND   PUBLIC   HEALTH 

to  the  air  in  drying;  and  symptoms  of  lead  poisoning  have  fre- 
quently been  observed  in  the  occupants  of  a  freshly  painted  room. 
Painting,  then,  is  not  to  be  recommended  for  wall  surfaces,  unless 
the  paints  are  warranted  free  from  lead.  Sometimes  the  paints 
themselves  contain  no  lead,  but  the  "  dryers  "  with  which  they 
are  mixed  before  use  are  found  to  be  full  of  lead. 

Varnished  wall-papers  are  coming  more  largely  into  use.  They 
have  a  smooth  non-absorbent  surface,  and  are  easily  cleaned  with 
a  damp  cloth.  In  papering  a  room  it  is  important  to  see  that  the 
old  paper  is  all  peeled  off,  and  the  plaster  underneath  well  washed, 
before  the  new  paper  is  applied.  The  size  and  paste  used  should 
be  perfectly  fresh. 

A  paper  should  never  be  put  on  a  wall  unless  it  is  guaranteed 
free  from  arsenic;  and  it  is  even  advisable  to  test  a  piece  with 
Marsh's  apparatus  to  make  perfectly  certain.  The  general  suppo- 
sition is  that  wall-papers  are  not  likely  to  contain  arsenic  unless 
they  are  coloured  some  shade  of  green.  But  arsenic  has  been 
found  in  various  coloured  papers — reds,  mauves,  browns,  and 
greys.  The  arsenite  of  copper  (Scheele's  green)  and  the  aceto- 
arsenite  of  copper  are  principally  used  in  the  manufacture  of  green 
papers.  The  amount  of  arsenic  present  has  been  found  to  vary 
in  different  cases  from  a  grain,  or  less,  per  square  yard  up  to  50 
or  60  grains. 

The  injurious  effects  of  arsenical  wall-papers  appear  to  be  due 
to  the  dissemination  of  volatile  arsenical  compounds,  or  of  solid 
particles  of  arsenious  acid  or  even  metallic  arsenic,  as  dust,  into 
the  air  of  the  apartment.  In  flock  papers,  coloured  with  arsenic, 
it  is  probably  diffused  as  dust;  whilst  in  the  smoother  papers, 
arseniuretted  hydrogen  or  other  volatile  compounds  are  formed 
by  the  decomposition  of  the  size  and  paste  on  a  damp  wall  acting 
chemically  on  the  arsenical  salt. 

The  long  continued  inhalation  into  the  lungs  or  swallowing  of 
the  arsenical  dust  and  vapours  derived  from  wall-papers  tends 
to  produce  a  chronic  form  of  poisoning,  characterized  by  one 
or  more  of  the  following  symptoms,  arranged  more  or  less  in  the 
order  of  their  appearance,  viz.,  conjunctivitis  and  lacrymation, 
cough,  nausea,  sickness  and  diarrhoia,  colic  pains,  cramps,  dry- 
ness of  the  mouth  and  throat  with  much  thirst,  headache  and 
gradually  increasing  debiUty,  with  actual  paralysis  of  the 
extremities,  terminating  in  convulsions  and  death. 

As  a  rule,  the  symptoms  do  not  go  beyond  conjunctivitis, 


AIR    AND    VENTILATION  207 

cougli,  nausea,  and  diarrhoea,  with  much  debiUty.  But  these 
cases  of  illness  often  last  for  a  long  period,  until,  indeed,  the 
source  of  the  poisoning  is  discovered.  The  artificial  fruit  and 
flower  makers  suffer  from  arsenic  poisoning  in  its  worst  forms. 

Ventilation  . 

Ventilation  is  a  term  which  has  a  somewhat  extensive  meaning. 
Generally  it  may  be  said  to  imply  the  removal  and  dispersion 
of  foreign  gases  or  suspended  matters,  which  have  accumulated 
in  the  atmosphere  as  the  result  of  the  vitiating  processes  already 
described.  We  speak  of  the  ventilation  of  streets  and  buildings, 
the  ventilation  of  inhabited  rooms,  factories,  and  mines,  and  the 
ventilation  of  drains  and  sewers.  In  each  case  the  same  object 
is  aimed  at,  but  the  means  by  which  it  can  be  attained  are 
different.  The  ventilation  of  streets  and  buildings  is  dependent 
upon  the  width  of  the  street,  and  the  height  of  adjoining  or 
opposite  buildings — in  fact,  upon  the  amount  of  free  air  space 
around  the  buildings,  and  the  facilities  afforded  for  the  entrance 
of  light  and  air.  This  may  be  called  external  ventilation.  To 
ventilate  dwelling  houses,  factories,  or  mines,  fresh  air  from  out- 
side must  be  introduced  within  these  more  or  less  closed  places  by 
natural  or  artificial  means,  and  adequate  exit  must  be  provided 
for  used  or  vitiated  air.  It  is  the  same  for  drains  and  sewers, 
with  this  addition,  that  the  escaping  air  must  be  allowed  exit  at 
points  where  it  is  least  likely  to  be  productive  of  nuisance  or 
danger.  In  addition  to  the  natural  forces  of  rain,  wind,  sun,  and 
vegetation,  which  promote  the  purification  of  the  atmosphere  on 
the  large  scale,  natural  ventilation  as  applied  to  circumscribed 
localities  may  be  said  to  depend  upon  (i)  diffusion  of  gases  ; 
(2)  the  action  of  the  loinds  ;  (3)  the  difference  in  -weight  of  masses  of 
air  of  unequal  temperature. 

1.  Gases  diffuse  inversely  as  the  square  roots  of  their  densities; 
and  this  diftusion  can  take  place  through  porous  substances  such 
as  dry  bricks.  The  process  is  necessarily  a  slow  one,  and  inade- 
quate to  produce  complete  renovation  of  vitiated  air. 

2.  Winds  are  very  powerful  ventilating  agents.  They  act 
chiefly  by  perflation,  i.e.,  by  setting  masses  of  air  in  motion, 
driving  them  onward  by  propulsion.  They  have  also  an  aspirating 
effect  on  air  which  is  shielded  from  the  direct  or  perflating  action. 
For  when  wind  passes  horizontally  over  chimneys,  or  tubes  placed 
at  right  angles  to  its  course,  it  causes  a  diminution  of  pressure 


208  HYGIENE   AND    PUBLIC    HEALTH 

within  them,  thus  creating  a  current  of  air  up  the  chimney.  The 
air  in  these  tubes  being  partially  aspirated  or  sucked  out  by  the 
action  of  the  wind,  to  restore  the  temporary  vacuum  so  made, 
air  from  below  rushes  up  to  take  its  place,  a  continuous  current 
in  a  perpendicular  direction  being  thus  set  up. 

3.  When  air  is  heated  it  expands.  The  expansion  is  equal  to 
jg^Y  of  its  volume  for  every  degree  Fahrenheit,  or  Trig  for  every 
degree  Centigrade.  A  volume  of  hot  air  is  consequently  lighter, 
bulk  for  bulk,  than  the  same  volume  of  colder  air.  The  warm 
air  rises,  and  equilibrium  is  restored  by  colder  air  rushing  in  to 
occupy  its  place.  The  winds  themselves  are  caused  in  this 
manner  by  the  unequal  heating  of  the  air  over  different  parts 
of  the  earth's  surface. 

External  Ventilation  {Streets,  Buildings,  etc.). 

The  health  of  a  town  largely  depends  on  the  width  of  its  streets, 
the  general  height  of  the  buildings,  and  the  amount  of  yard  space 
at  the  rear  of  each  building  which  separates  it  from  its  opposite 
neighbour.  Contrast  the  health  and  vitality  of  the  occupants 
of  houses  in  wide  open  streets  with  those  who  live  in  narrow  courts 
closed  at  one  or  both  ends,  the  courts  themselves  being  surrounded 
by  higher  buildings,  or  built  back  to  back,  or  with  the  smallest 
possible  intervening  space.  In  such  places  the  air  is  almost 
always  necessarily  stagnant,  as  the  passage  of  the  wind  is  ob- 
structed by  the  surrounding  buildings.  The  sun's  light — the 
most  powerful  of  germicides — for  many  months  in  the  year 
cannot  penetrate,  with  the  result  that  the  ground  is  never 
thoroughly  dried,  and  the  air  in  contact  with  it  remains  continu- 
ously damp.  Impure  gases  and  exhalations,  evolved  from  the 
inhabited  dwellings,  are  not  at  once  swept  away  by  the  wind, 
and  consequently  accumulate  in  the  air  of  the  court  and  its  sur- 
roundings. Suspended  organic  matters  tend  to  accumulate  in 
the  still  air,  which,  being  thus  both  damp  and  impure,  produces 
that  state  of  low  vitality  and  predisposition  to  disease  which 
characterize  the  inhabitants  of  such  places. 

Zymotic  diseases — -especially  typhus — when  once  introduced, 
spread  rapidly  through  the  vitiated  air,  the  enfeebled  constitu- 
tions of  the  inhabitants  presenting  but  slight  resistance  to  their 
onset.  Absence  of  sunlight  appears  to  have  a  specially  injurious 
effect  on  child  Hfe,  which,  like  plants,  becomes  blanched  and 
weakly  when  reared  in  semi-darkness.     When  it  is  added  that  in 


AIR   AND   VENTILATION  209 

many  of  these  courts  and  alleys  the  houses  have  no  through  venti- 
lation, the  windows  being  only  in  front  of  the  house,  it  is  not  to 
be  wondered  at  that  the  general  death-rate  is  sometimes  double, 
or  even  treble,  that  of  the  healthy  parts  of  the  town,  and  that 
the  mortahty  amongst  infants  and  young  children  is  appalling. 
All  investigations  into  the  effect  of  back-to-back  houses  upon  the 
health  of  the  inmates  show  an  increased  incidence  of  disease  and 
mortality  from  all  causes,  phthisis,  diseases  of  the  respiratory 
organs,  diarrhoea,  and  zymotic  diseases  generally;  and  in  dis- 
tricts where  such  houses  form  about  50  per  cent,  of  the  total,  the 
death-rates  from  the  above-mentioned  causes  are  nearly  half  as 
much  again  as  the  rates  generally  prevailing  for  the  whole  of 
England  and  Wales.  Back-to-back  houses  are  built  in  double 
rows  with  only  one  side  exposed  to  the  open  air,  except  in  the 
case  of  those  houses  at  the  ends  of  the  blocks,  which  have  two 
sides  open  to  the  external  air.  Through  ventilation  is  impossible 
in  such  houses,  and  the  rooms  are  generally  dark  and  dirty  as 
a  consequence. 

To  show  what  is  the  minimum  amount  of  external  air-space 
which  should  be  allotted  to  every  building  in  a  town,  we  may 
quote  from  the  model  bye-laws  of  the  Local  Government  Board, 
which  refer  to  new  streets  and  buildings. 

The  width  of  every  street  intended  for  use  as  a  carriage  road 
must  not  be  less  than  36  feet ;  if  not  to  be  used  as  a  carriage  road 
it  must  be  at  least  24  feet  wide,  and  open  at  one  end.  Twenty- 
four  feet  is  the  least  width  allowed  before  the  frontage  of  any  new 
building;  and  the  aggregate  amount  of  yard  space  at  the  back 
of  such  a  building,  and  belonging  to  it,  must  not  be  less  than 
150  square  feet,  and,  whilst  extending  the  entire  width  of  the 
building,  it  must  not  in  any  case  be  less  than  10  feet  wide,  and 
must  be  wider  when  the  height  of  the  building  exceeds  15  feet. 

It  is  important  to  note  that  the  model  bye-laws  insist  on  the 
yard  space  at  the  back  of  a  house  being  increased  with  the  height 
of  the  house  up  to  35  feet,  but  not  so  the  frontage  area.  The 
higher  the  buildings,  of  course  the  greater  the  obstruction  to  the 
passage  of  air  and  light,  and  the  amount  of  space  compulsorily 
left  unoccupied  (both  in  front  and  back)  should  have  been 
correspondingly  increased.  The  erection  in  London  and  some 
large  provincial  towns  of  huge  blocks  of  industrial  dwellings, 
whilst  affording  vastly  superior  accommodation  to  the  working 
classes  over  the  old  insanitary  tenements,  has  not  always  secured 

14 


2IO  HYGIENE    AND    PUBLIC    HEALTH 

efficient  external  ventilation  for  certain  of  the  tenements.  Lofty 
blocks  are  too  often  built  in  such  a  way  as  to  enclose  a  narrow 
and  well-like  court,  in  which  the  atmosphere  is  always  sunless 
and  stagnant,  and  from  which  the  rooms  facing  on  to  it  derive  all 
their  light  and  air.  Cottage  buildings  with  sufficient  space  in 
front  and  rear  are  far  preferable  to  lofty  blocks  placed  in  rows; 
but  as  they  do  not  house  the  same  number  of  people  for  the  space 
occupied,  in  crowded  districts,  where  the  land  is  of  such  enormous 
value,  the  rents  must  necessarily  be  higher. 

The  London  Building  Act,  1894,  Part  V.,  provides  for  open  spaces  about 
buildings  and  the  height  of  buildings.  Section  41  applies  to  domestic 
buildings  erected  after  the  commencement  of  the  Act  and  abutting  upon 
a  street  formed  or  laid  out  after  the  commencement  of  the  Act,  and 
requires  to  be  provided  in  the  rear  of  every  such  building  an  open  space 
exclusively  belonging  to  it  of  an  aggregate  extent  of  not  less  than  150 
square  feet,  the  open  space  to  extend  throughout  the  entire  width  to  a 
depth  of  at  least  10  feet  from  the  building.  The  height  of  the  building  is 
regulated  as  follows:  An  imaginary  horizontal  line  is  drawn  at  the  level 
of  the  pavement  from  the  roadway,  and  at  right  angles  to  it  through  the 
centre  of  the  face  of  the  building,  and  prolonged  to  intersect  the  boundary 
of  the  open  space  at  the  rear.  An  imaginary  diagonal  line  is  then  drawn  in 
the  direction  of  the  building  above,  and  in  the  same  vertical  plane  with 
the  horizontal  line,  and  inclined  thereto  at  an  angle  of  63-5°,  meeting  the 
horizontal  line  where  it  intersects  the  boundary  of  the  open  space  at  the 
rear.  No  part  of  the  building  will  then  be  allowed  to  extend  above  the 
diagonal  line,  except  chimneys,  dormers,  gables,  turrets,  or  other  archi- 
tectural ornaments.  Exception  is  made  in  the  case  of  new  buildings 
abutting  at  the  back  upon  a  street  or  open  space  dedicated  to  the  public. 

With  respect  to  new  domestic  buildings  abutting  upon  a  street  formed 
or  laid  out  before  the  commencement  of  the  Act,  the  horizontal  line  may 
be  drawn  at  a  level  of  16  feet  above  the  level  of  the  adjoining  pavement, 
and  the  open  space  of  1 50  square  feet  may  also  be  provided  above  the  level 
of  the  ceiling  of  the  ground  story,  or  16  feet  above  the  level  of  the  adjoining 
pavement. 

Section  42  enacts  that  the  sanction  of  the  London  County  Council  must 
be  obtained  to  the  plans  of  dwellings  for  the  working  classes  to  be  erected 
after  the  commencement  of  the  Act,  which  do  not  abut  upon  a  street. 

Section  45  prohibits  the  construction  of  habitable  rooms  lighted  and 
ventilated  entirely  from  enclosed  coui-tyards,  or  from  courtyards  open  on 
one  side,  but  of  which  the  depth,  measured  from  the  open  side,  exceeds 
twice  the  width,  unless  the  width  of  the  court  measured  from  the  window 
of  the  room  to  the  opposite  wall  is  equal  to  half  the  height  measured  from 
the  sill  of  the  window  to  the  eaves  or  top  of  the  parapet  of  the  opposite  wall. 

Section  43  enables  new  domestic  buildings,  which  are  not  artisans' 
dwellings,  to  be  erected  on  the  same  sites  as  existing  buildings,  if  abutting 
upon  a  street,  and  to  cover  the  same  extent  of  land,  but  no  more  than  was 
occupied  by  the  previously  existing  domestic  building. 

Section  47  enacts  that  a  building  (not  being  a  church  or  chapel)  shall  not 
be  erected  of  or  be  subsequently  increased  to  a  greater  height  than  80  feet 
(exclusive  of  two  stories  in  the  roof,  and  of  ornamental  towers,  turrets,  or 
other  architectural  features)  without  the  consent  of  the  Council ;  provided 
that  where  any  existing  buildings  forming  part  of  a  continuous  block  or 
row  of  buildings  exceed  80  feet  in  height,  any  other  building  in  the  same 
block  belonging  to  the  same  owner  at  the  date  of  the  passing  of  the  Act 


AIR    AND    VENTILATION  211 

may  be  carried  to  a  height  equal  to,  but  not  exceeding,  that  of  the  existing 
buildings. 

Section  49  requires  that  no  existing  building  (other  than  a  church  or 
chapel)  on  the  side  of  a  street  formed  or  laid  out  after  August  7,  1862,  and 
of  a  less  width  than  50  feet,  shall  be  raised,  nor  shall  any  building  be  erected 
so  that  the  height  of  the  building  exceeds  the  width  of  the  street,  without 
the  consent  of  the  Council. 

Section  69  provides  for  the  ventilation  of  staircases  both  in  artisans' 
dwellings  and  in  ordinary  dwelling  houses  constructed  after  the  Act. 

Section  jo  requires  that  every  liabitable  room  in  a  new  building,  except 
rooms  wholly  or  partly  in  the  roof,  shall  be  in  every  part  at  least  <S  feet 
6  inches  in  height  froni  door  to  ceiling.  Rooms  wholly  or  partly  in  the  roof 
must  be  at  least  8  feet  in  height  throughout  not  less  than  one-half  their 
area.  Every  habitable  room  with  an  external  wall,  which  is  not  in  the  roof, 
must  have  a  window  opening  into  the  external  air,  or  into  a  conservatory, 
with  a  total  superficies  clear  of  the  sash  frames,  free  from  any  obstruction 
to  the  light,  equal  to  at  least  one-tenth  of  the  floor  area  of  the  room,  and  so 
constructed  that  at  least  one  half  of  such  window  can  be  opened,  the 
opening  to  extend  to  at  least  7  feet  above  the  floor  level. 

Smoke  Prevention. 

In  London  the  smoky  atmosphere  of  the  winter  months  is 
almost  entirely  due  to  the  unconsumed  smoke  from  private 
dwelHng  houses,  whilst  in  the  Northern  towns  it  is  the  manu- 
factory smoke  that  pollutes  the  air,  a  fact  at  once  evident  from 
the  very  striking  contrast  between  the  air  on  Sundays  and  the 
dense  smoke  cloud  that  overhangs  the  town  on  the  working 
weekdays.  To  deal  with  the  whole  smoke  question  in  London  is 
to  attack  a  problem  of  unexampled  magnitude  and  difficulty; 
all  that  can  be  hoped  for  is  that  coal  gas  may  in  time  be  so  far 
cheapened  as  to  replace  with  economy  the  common  use  of  coal  for 
domestic  heating  and  cooking  purposes.  A  smoke-laden  atmo- 
sphere is  impure;  it  reduces  daylight,  and  therefore  leads  to  an 
increased  employment  of  artificial  fight ;  it  renders  it  difficult  and 
sometimes  impossible  to  keep  public  buildings  and  private  dwell- 
ings clean,  and  it  doubtless  promotes  ill-health  in  some  people. 

In  the  Lancashire  and  Yorkshire  towns  the  abatement  of  smoke 
is  a  far  easier  task  to  accomplish,  and  already  a  good  deal  has  been 
done  in  this  direction  by  the  adoption  of  smoke-preventing 
appliances  in  connection  with  factory  furnaces.  The  smoke 
nuisance  is  chiefly  due  to  the  fireman  allowing  too  long  intervals 
between  the  firings.  This  leads  to  too  much  coal  being  put  on  at 
one  firing,  and  the  issue  of  black  smoke;  but  a  deficient  air 
draught — often  due  to  a  small  cramped  flue  in  a  low  chimney — is 
frequently  a  cause.  The  best  method  of  smoke  prevention  is  to 
secure  frequent  and  fight  firing,  and  the  admittance  to  the  furnace 


212  HYGIENE   AND   PUBLIC    HEALTH 

of  the  necessary  air  to  provide  complete  combustion  of  the  carbon 
particles  after  each  fresh  charge  of  fuel.  Many  devices  are  em- 
ployed to  secure  these  objects  independently  of  the  fireman.  Of 
these  appliances,  perhaps  the  most  commonly  used  are  the 
mechanical  stokers,  which  may  conveniently  be  divided  into  two 
classes:  (a)  Those  that  throw  small  quantities  of  fuel  evenly  over 
the  fire,  and  thus  obviate  the  dense  black  smoke  produced,  under 
the  ordinary  conditions  of  stoking,  when  the  fire  door  is  opened 
and  fresh  fuel  is  cast  by  a  fireman  on  the  lire.  It  is  evident  that 
with  stokers  of  this  class  ("  sprinklers  ")  the  fire  bars  must  be 
made  to  move  by  appropriate  mechanical  arrangements,  and  so 
keep  the  fire  level  and  free  from  aggregations  of  imperfectly  coked 
fuel  at  certain  parts  of  the  furnace. 

The  second  class  of  mechanical  stokers  {b)  are  those  of  the 
coking  class.  By  these  the  fresh  fuel  is  deHvered  from  a  hopper 
to  the  front  of  the  fire,  where  it  gets  coked;  it  is  then  gradually 
worked  backwards  on  the  fire  bars,  until  the  clinker  falls  over  the 
back  of  the  grate  into  the  ashpit.  By  these  contrivances  the 
furnace  is  continuously  taking  in  the  raw  fuel  at  the  front,  burning 
this  smokelessly  (because  the  black  smoke  arising  at  the  front  of 
the  furnace  is  "  killed  "  by  passing  over  the  white  hot  fuel  at  the 
back),  and  dropping  the  ashes  over  the  other  end  of  the  bar. 
"  Side  firing  "  is  said  to  give  good  results.  By  this  method  the 
fuel  is  delivered  at  each  side  of  the  fire  alternately,  and  the  smoke 
from  the  side  which  is  being  fed  curls  towards  the  incandescent 
fire  on  the  other  side,  and  gets  burned.  These  coking  mechanical 
stokers  give  far  better  results  than  the  sprinkling  class. 

As  smoke  arises  from  a  furnace  when  the  supply  of  air  admitted 
is  inadequate  to  secure  complete  combustion  of  the  fuel,  a  great 
number  of  contrivances  have  been  invented  for  suppl3dng  air 
either  heated  by  passing  through  special  pipes  laid  in  the  flues, 
or  cold,  to  various  parts  of  the  furnace  or  main  flue.  Grids  or 
circulars  which  can  be  opened  and  shut  by  hand  are  sometimes 
placed  in  the  door  to  admit  air  to  the  furnace,  and  panels  and 
louvres  in  the  furnace  door  arc  now  made  to  open  and  shut  auto- 
matically. These  can  be  regulated  to  admit  the  desired  quantity 
of  air.  "  Forced  draughts  "  are  often  utilized  to  increase  the 
draught  in  the  furnace,  and  thus  to  favour  combustion,  and  for 
this  purpose  jets  of  steam  are  generally  admitted  through  the 
frame  of  the  furnace  just  above  the  door.  Again,  split  bridges 
or  hollow  fire  bars  of  various  kinds  are  made  to  admit  air.     The 


AIR   AND   VENTILATION  2l3 

"  bridge  "  is  the  metal  or  brickwork  projection  at  the  back  of  the 
fire  bars,  over  which  the  flames  and  products  of  combustion  pass 
on  their  way  to  the  flue.  There  is  a  door  underneath  the  split 
bridge,  which  can  be  opened,  when  firing  is  taking  place,  to  let 
the  air  pass  up  through  the  bridge  to  ignite  the  gases  passing  over 
it  and  further  complete  combustion.  Spht  bridges  may  be  made 
to  work  automatically,  and  many  are  in  use ;  but  if  left  continuallj' 
open,  they  tend  to  destroy  the  draught  in  the  front  part  of  the 
furnace,  and  they  soon  get  filled  with  ashes. 

Revolving  cast-iron  chain  grates  are  now  being  used  in  certain 
classes  of  furnace  in  connection  with  mechanical  stokers.  The 
revolving  grate  carries  the  incandescent  fuel  slowly  from  the  front 
to  the  back  of  the  furnace,  where  the  spent  fuel  falls  into  the 
ashpit.  These  grates  are  intended  for  consuming  soft  coal,  and 
not  Welsh  steam  coal,  the  excessive  heat  from  the  latter  being 
too  speedily  destructive  of  the  cast-iron  chains. 

Amongst  less  effective  appliances  may  be  mentioned  the  use 
of  fans  to  force  the  smoke  again  through  the  furnace,  and  the 
washing  of  the  smoke  by  passing  it  through  shafts  in  which  sprays 
of  water  are  descending. 

There  is  a  considerable  advantage  to  the  manufacturers  in 
the  use  of  mechanical  stokers,  inasmuch  as  they  can  by  their 
means  burn  an  inferior  slack  coal  (cheaper  fuel),  and  less  labour 
is  required.  If  split  bridges  only  are  used,  great  care  is  required 
on  the  part  of  the  fireman,  and  fuel  of  fair  quality  must  be  used, 
or  smoke  is  emitted ;  whilst  the  mechanical  stokers  do  away  with 
these  sources  of  expense. 

In  conclusion,  it  may  be  said  that  the  quality  of  the  coal  used 
has  an  important  bearing  on  the  subject  of  smoke  prevention, 
and  that  coke  and  anthracite  are  practically  smokeless.  The 
ordinary  or  bituminous  coal  is  much  cheaper,  weight  for  weight, 
than  anthracite,  but  on  account  of  the  greater  heat  obtained 
from  the  latter  it  is  said  to  be  almost  as  cheap  in  use.  Coal  dust 
firing  is  held  by  a  recent  Prussian  Commission  to  possess  the 
following  advantages:  It  allows  of  uniform  distribution;  it  per- 
mits of  perfect  combustion  without  smoke;  and  secures  the 
greatest  calorific  efficiency. 

Section  91  of  the  PubHc  Health  Act,  1875,  defines  as  a  nuisance 
"  any  fire-place  or  furnace  which  does  not  as  far  as  practicable 
consume  the  smoke  arising  from  the  combustible  used  therein, 
.  .  .  and  which  is  used  in  any  manufacturing  or  trade  process 


214  HYGIENE   AND   PUBLIC   HEALTH 

whatsoever."  The  same  section  provides  that  the  court  shall 
dismiss  the  complaint  if  it  is  satisfied  that  such  furnace  is  con- 
structed in  such  a  manner  as  to  consume  its  smoke  as  far  as 
practicable.  It  should  be  noted  that,  according  to  the  same 
section,  when  any  chimney  (not  being  the  chimney  of  a  private 
dwelhng  house)  is  sending  forth  black  smoke  in  such  quantity  as 
to  be  a  nuisance,  it  is  not  necessary  to  prove,  in  order  to  secure 
a  conviction,  that  the  furnace  is  improperly  constructed  or 
inefficiently  tended.  A  notice  "  to  abate  "  must  precede  a 
summons,  as  in  the  case  of  other  nuisances;  and  a  conviction 
must  follow  the  proof  of  the  emission  of  "  black  smoke  in  such 
quantity  as  to  be  a  nuisance." 

The  London  County  Council  is  of  opinion  that  the  escape  of 
black  smoke  for  five  minutes  from  the  lighting  of  the  furnace 
might  be  permitted,  but  that  afterwards  a  discharge  of  one 
minute  or  more  should  be  the  subject  of  legal  procedure.  The 
allowance  varies  from  two  to  fifteen  minutes  in  other  large 
towns. 

In  Sheffield  the  following  working  limits  must  not  be  ex- 
ceeded:— 

1  boiler  .  .     2     minutes  of  black  smoke  in  the  hour. 

2  boilers         .  .      3  ,,  ,,  ,,  ,, 

3  ..  •  •     4 

4  ,,         and  more    6  ,,  ,,  ,,  ,, 

Ventilation  of  Inhabited  Rooms. 

In  providing  for  the  ventilation  of  inhabited  rooms  by  the 
replacement  of  vitiated  air  by  fresh  air,  it  has  been  found  neces- 
sary to  adopt  a  certain  standard  of  impurity  above  which  no 
increase  should  be  allowed.  It  is  only  out  of  doors,  then,  that 
we  can  be  constantly  breathing  air  of  normal  purity,  as  indicated 
by  the  amount  of  CO^  (0-4  per  1,000). 

Pettenkofer  proposed  as  a  standard  for  inhabited  rooms 
I  volume  of  CO.,  per  1,000  of  air.  Carnelly,  Anderson,  and 
Haldane  proposed  1-3  per  1,000  for  elementary  schools  during 
the  daytime,  and  i  per  1,000  for  dormitories  at  night.  The 
only  legal  maximum  standard  at  present  in  force  is  that  fixed 
by  the  Home  Office  in  respect  of  cotton-cloth  factories,  where 
the  air  requires  to  be  humidified  by  the  addition  of  steam, 
namely  0-9  vols,  of  COg  per  1,000. 

It  was  found  by  the  late  Professor  de  Chaumont,  by  chemical 


AIR   AND    VENfltATrONr  215 

examination  of  a  large  number  of  samples  of  the  air  of  inhabited 
rooms,  that — the  amount  of  COg  in  the  outer  air  being  004 
per  cent.,  or  04  per  1,000 — -no  close  or  disagreeable  smell  is 
perceived  in  the  air  of  a  room  until  the  COg  from  human  respira- 
tion reaches  o-6  per  1,000,  or  exceeds  by  02  per  1,000  that  present 
in  outer  air,  the  close  smell  being  always  due  to  the  foul  organic 
matter  in  the  impure  air,  which  increases  pari  passu  with,  and  is 
therefore  estimated  by,  the  amount  of  CO2  present.  When  the 
CO2  in  an  inhabited  room  reaches  1-3  per  1,000,  the  Hmit  of 
differentiation  by  the  sense  of  smell,  when  a  person  first  enters 
such  a  room  from  the  outer  air,  is  reached.  Any  greater  impurity 
than  this  cannot  be  distinguished  by  the  unaided  senses.  It 
was  assumed  by  De  Chaumont  that  air  vitiated  to  the  extent 
of  0-2  per  1,000 — air  which  is  still  fresh  and  does  not  differ 
sensibly  to  smell  from  the  outer  atmosphere — can  be  breathed 
with  impunity,  but  that  no  greater  vitiation  ought  to  be  allowed. 
Ideal  ventilation  may  be  said  to  be  the  supply  of  sufficient  pure 
air  to  a  room  to  prevent  the  respiratory  CO2  increasing  beyond 
0-2  part  per  1,000.  The  permissible  limit  of  respiratory  impurity 
is  therefore  generally  held  to  be  o-2  per  1,000  (which  is  the  same 
thing  as  0-0002  cubic  foot  of  CO2  per  i  cubic  foot  of  air). 

By  the  equation  D  =    — where  E  =  amount  of  CO.,  exhaled, 
r 

y=  respiratory  impurity  per  cubic  foot  of  air,  and  D=the  de- 
livery, or  the  amount  of  fresh  air  available  in  cubic  feet — if 
E  and  r  are  known  we  can  find  D,  or  if  D  and  E  are  known  we 

_         0-6 
can  find  y.     If  E=  o-6,i  and  r- 00002,  then  D=  =3,000. 

00002 

That  is  to  say,  each  individual  requires  3,000  cubic  feet  of  fresh 

air  per  hour  in  order  that  the  respiratory  impurity  may  not  exceed 

0-2  per  1,000,  or — what  is  the  same  thing — the  total  impurity 

0-6  per  1,000. 

In  a  similar  way  it  can  be  shown  that  when  the  adult  male 

is  doing  gentle  work  (and  giving  off  09  cubic  foot  of  CO^  in  the 

1  A  man  at  rest  inspires  and  expires  about  17  times  a  minute;  at  each 
inspiration  about  30  cubic  inches  of  air  are  taken  into  the  lungs  and  sub- 
sequently expired.  The  cubic  feet  of  air  inspired  and  expired  in  one  hour 
will  be  17  X  30x60^^^.^      ^^  ^j^g  (.Q^  gj^g  jj^  j^-j.  expired  from  the  lungs 

1728 
amounts  on  the  average  to  4  per  cent,  by  volume,  the  amount  of  COg 
given  off  in  an  hour  will  be    ^^jyX  i7-6=o-7   cubic  foot.     For  a  mixed 
population  of  men,  women,  and  children,  the  amount  of  CO2  is  generally 
taken  as  o-6  cubic  foot  per  head. 


2l6  HYGIENE    AND   PUBLIC   HEALTH 

hour)  he  theoretically  requires  4,500  cubic  feet  of  fresh  air  per 
hour;  and  if  he  is  engaged  in  very  hard  work  (and  giving  off,  may- 
be, 1-8  cubic  foot  of  CO.,  per  hour)  he  needs  as  much  as  9,000. 

Example. — If  a  room  of  1,000  cubic  feet  is  occupied  for  four  hours  by 
10  persons,  each  giving  off  the  average  amount  of  COg,  what  will  be  the 
total  amount  of  COg  per  1,000  volumes  at  the  end  of  the  time,  supposing 
10,000  cubic  feet  of  fresh  air  per  hour  have  been  supplied  ? 

In  this  problem  D  and  E  are  given,  and  we  have  to  find  r.  The  total 
amount  of  air  available  for  breathing  by  the  10  persons  in  the  four  hours  is 
1,000  cubic  feet  (the  cubic  space  of  the  room)+  10,000x4  (the  amount 
in  cubic  feet  supplied  in  four  hours)  =  41,000  cubic  feet  =  D.  The  amount 
of  COg  expired  by  10  persons  in  4  hours=o-6xiox4  =  24  cubic  feet  =  E. 

_      E  E         24 

u  —  — orr=--=      =o-oooi;8  per  unit: 

r  D     41,000 

i.e.,  r,  or  the  respiratory  impurity  is  0*58  part  per  1,000.     The  total  amount 

of  CO2  in  the  air  will  be  o-58+o-4  =  o*98  part  per  1,000. 

Example. — The  air  of  a  room  occupied  by  6  persons,  and  containing 
5,000  cubic  feet  of  space,  yields  7-5  parts  of  COg  per  10,000  parts.  How 
much  air  is  being  supplied  per  person  per  hour  ? 

Here  E  and  r  are  given,  and  we  have  to  find  D.     E=o-6  x  6=3-6  cubic 
feet  COg  exhaled  in  i  hour.     ^=7*5  -  4=  3' 5  per  10,000,  or  0-35  per  1,000 
or  0-00035  part  of  COg  per  cubic  foot. 

D=— ^ =  10,285. 

0-00035 

But  the  room  contains   5,o(;;o  cubic  leet  of  space;  therefore  in  the  first 

hour  5,285  cubic  feet  of  fresh  air  were  supplied,  or  880  cubic  feet  per  head. 

After  the  first  hour,  to  maintain  the  same  amount  of  COg  in  the  air,  the 

full  10,285  cubic  feet  of  fresh  air  will  have  to  be  supplied,  or  1,714  cubic  feet 

of  fresh  air  per  head  per  hour. 

During  exertion  a  man  gives  off  more  respiratory  impurities 
(CO.j,  organic  matters,  etc.)  than  when  at  rest.  For  this  reason, 
and  also  because  the  air  is  generally  further  vitiated  by  the 
trade  process,  the  amount  of  air  supplied  to  factories  or  work- 
rooms should  be  considerably  in  excess — double,  or  even  treble, 
according  to  the  nature  of  the  work — of  that  required  in  au 
ordinary  living  or  sleeping  apartment.  Some  allowance,  too, 
nmst  be  made  for  lights,  especially  gaslights,  when  the  products 
of  combustion  are  allowed  to  escape  into  the  air  of  the  room. 

The  amount  of  cnhic  space  allotted  to  each  person  in  a  room 
is  a  matter  of  great  importance,  not  because  cubic  space,  how- 
ever large  in  amount  (as  met  with  under  ordinary  conditions 
of  inhabited  dwellings),  can  take  the  place  of  a  regular  supply  of 
fresh  air  from  outside,  but  because  the  larger  the  cubic  space, 
the  easier  it  is  to  supply  the  proper  amount  of  air  without  creating 
a  draught.  For  instance,  suppose  in  a  dormitory  occupied  by 
ten  persons  the  amoimt  of  space  per  head  is  only  300  cubic  feet, 
to  supply  J, 000  cubic  feet  of  fresli  air  per  head  per  hour  30,000 


AIR    AND    VENTILATION  2I7 

cubic  feet  must  be  admitted  in  this  period,  and  the  air  of  the 
room  will  have  to  be  completely  changed  ten  times — a  proceeding 
which  would  cause  in  cold  weather,  unless  the  entering  air  was 
warmed,  a  most  disagreeable  draught.  But  if  the  cubic  space 
per  head  be  i,ooo  cubic  feet,  then  the  air  of  the  dormitory  need 
be  changed  only  three  times  per  hour;  and  if  such  renewal  is 
effected  steadily  and  gradually,  the  cold  entering  air  is  broken 
up,  and,  mixing  with  the  warmer  air  of  the  compartment,  creates 
no  draught. 

A  certain  amount  of  superficial  or  floor  space  is  necessary  for 
each  individual,  for  if  the  height  of  the  room  is  much  over 
12  feet,  excess  in  this  direction  does  not  compensate  for  deficiency 
in  the  other  dimensions,  although  the  total  cubic  space  may  be 
the  same;  thus,  it  would  not  be  the  same  thing  to  allow  a  man 
50  square  feet  of  floor  space  in  a  room  20  feet  high  as  to  provide 
100  square  feet  in  a  room  10  feet  high,  although  the  cubic  space 
would  be  identical.  The  reason  is  that  the  products  of  respira- 
tion are  not  readily  diffused  throughout  the  air  of  an  apartment, 
but  tend  to  accumulate  in  the  lower  strata,  consequently  excessive 
height  does  not,  in  their  case,  mean  a  corresponding  dilution. 

Haldane  and  Osborn  in  their  examination  of  the  air  of  factories 
and  workshops  found  that  some  of  the  rooms,  where  there  was 
the  largest  amount  of  cubic  space  per  head,  contained  the  foulest 
atmospheres,  there  being  no  proper  means  of  ventilation,  the 
air  never  being  thoroughly  renewed,  even  when  the  rooms  were 
empty. 

The  cubic  and  superficial  space  allotted  under  various  statutes, 
bye-laws  and  regulations  are  given  in  table  on  p.  218. 

In  the  large  public  schools  of  this  country  the  amount  of  super- 
ficial area  and  cubic  space  varies  according  to  the  ages  of  the 
boys  and  other  circumstances.  Average  requirements  for  boys  of 
12-18  years  of  age  are  70-80  square  feet  of  floor  space  and  700 
to  900  cubic  feet  of  air  space;  but,  as  previously  pointed  out, 
ample  floor  and  cubic  space  will  not  compensate  for  defective 
ventilation.  Unhealthy  conditions  of  atmosphere  are  sometimes 
found  to  prevail  in  large  and  lofty  dormitories,  where  defective 
ventilation  leads  to  stagnation  of  air. 

Natural  Ventilation. — During  the  colder  months  of  the  year 
in  this  country  three  complete  changes  per  hour  of  the  air  in  an 
inhabited  room  is  all  that  can  be  borne  when  the  entering  air  is 
not  artificially  warmed.     Hence  the  importance  of  an  allowance 


2l8 


HYGIENE    AND    PUBLIC    HEALTH 


for  each  individual  of  cubic  space  not  much  less  than  1,000  cubic 
feet.  The  area  of  the  inlet  opening  should  be  sufficiently  large 
to  allow  the  required  volume  of  air  (3,000  cubic  feet)  to  enter  at 
no  greater  speed  than  5  feet  per  second.  This  speed  could  be 
attained  where  the  inlet  opening  for  each  individual  was  24  square 
inches.  During  cold  weather  this  velocity  could  not  be  borne; 
and  it  may  be  said  generally  that  efficient  ventilation  is  difficult 


Minimum 

Space  per 
Head  in 

Authority. 

Cubic  Feet. 

Common  lodging    houses   (sleeping 

300     1  Local  Government  Board 

rooms) 

(Model  Bye -laws). 

Registered  lodging  houses — 

Rooms  occupied  by  day  and  night 

400 

Ditto             Ditto 

Rooms  occupied  by  night  only     . 

300 

Ditto             Ditto 

Non-textile  workrooms   . 

250 

Factory  Act,  1901. 

Non-textile  workrooms  during  over- 

time              ..... 

400 

,,              ,, 

Underground  Bakehouses 

500 

Order  under  Factory  Act, 

Above  ground  bakehouses 

400  eft. 

190 1 . 
Order  under  Factory  Act, 

where  night  work  is  car- 

between 

1 90 1. 

ried  on  by  artificial  light 

9  p.m. 

other  than  electric  light 

and 
6  a.m. 

A-rmy  barracks        .... 

600       British  Army  Regulations. 

Army  hospital  wards 

1,200 

Ditto             Ditto 

Public  elementary  schools 

80 1 

Education  Department. 

London  County  Council  Schools 

1302 

London  County  Council. 

Canal  boats  (persons  over  1 2  years) 
Canal  boats  (persons  under  1 2  years) 

6o3 
40  3 

I^  Local  Government  Board 
]     Regulations  under  the 
[    Canal  Boats  Act,  1877. 

Seamen's  cabins      .... 

120 

Merchant    Shipping   Act , 
1906. 

Cows  in  cowsheds  .... 

800 

Local  Government  Board. 
Model  Regulations  under 
the    Dairies,    Cowsheds, 
and  Milkshops  Order. 

to  procure  in  cold  weather,  unless  the  entering  air  is  artificially 
warmed.  A  velocity  of  the  entering  air  of  2  to  3  feet  per  second 
is  far  more  agreeable  to  the  senses  than  a  velocity  of  5  feet. 
If  the  entering  air  is  artificially  warmed,  the  size  of  the  inlet 
opening  may  even  be  increased  up  to  70  or  80  square  inches 
per  head,  and  the  amount  of  cubic  space  may  be  diminished,  for 

^  Minimum  floor  space  8  square  feet. 

2  Minimum  floor  space  10  square  feet. 

3  An  after-cabin  must  not  be  less  than  180  cubic  feet  in  capacity  nor  a 
fore-cabin  less  than  80. 


AIR    AND    VENTILATION  2I9 

it  would  be  possible  then  to  change  the  air  of  the  apartment 
more  frequently  than  three  times  per  hour  without  creating  a 
draught. 

Of  the  forces  which  act  in  natural  ventilation,  diffusion  causes 
the  gaseous  impurities  of  respired  air  to  mix  with  the  fresh  air  in 
a  room  until  homogeneity  is  estabhshed.  DifiEusion,  however, 
does  not  affect  the  suspended  matters,  which  tend  to  fall  towards 
the  earth  in  a  still  atmosphere. 

The  perflating  action  of  the  wind  may  be  utiUzed  by  opening 
windows  facing  the  wind,  and  the  action  is  increased  when 
windows,  or  a  window  and  door  on  opposite  sides  of  a  room,  are 
left  open.  The  room  is  rapidly  and  continuously  flushed  with 
air,  an  enormous  effect  being  produced,  for  it  is  possible  to  renew 
the  air  of  a  room  in  this  manner  over  a  hundred  times  an  hour, 
even  when  the  movement  of  the  wind  outside  is  only  3  feet  per 
second,  equivalent  to  a  very  little  breeze.  Such  a  method  is  of 
unquestionable  utiUty  for  rapidly  changing  the  air  of  an  unoccu- 
pied room — especially  school  and  work  rooms— and  may  be 
generally  put  in  operation  in  inhabited  rooms  in  summer  when 
the  temperatures  outside  and  inside  the  house  approximate. 

In  any  system  of  ventilation,  however,  that  depends  entirely 
on  the  wind,  there  is  always  the  difficulty  of  regulating  the 
velocity  of  the  current,  and  during  complete  calms  the  action 
is  of  course  nil.  The  wind,  too,  often  impedes  ventilation  by 
obstructing  the  passage  of  vitiated  air  from  an  exit  shaft  into 
whose  mouth  it  blows;  and  this  is  not  to  be  wondered  at,  for 
when  blowing  at  the  rate  of  10  miles  an  hour  the  pressure  of 
the  wind  is  J  pound  on  each  square  foot  of  surface. 

For  ventilating  the  holds  and  cabins  of  ships  at  sea,  the  wind 
may  be  most  advantageously  utiUzed,  because  the  ship's  motion 
is  almost  always  producing  a  breeze.  A  large  cowl,  placed  so  as 
to  face  the  wind,  conducts  the  air  below  by  means  of  a  pipe, 
whilst  another  cowl,  reversed  so  as  to  back  to  the  wind,  allows 
the  used  air  to  escape.  By  this  exit  shaft  the  aspirating  force 
of  the  wind  is  utiHzed.  Sylvester's  system  of  house  ventilation 
proceeds  on  these  principles.  A  large  cowl  facing  the  wind 
is  placed  outside  the  house,  and  conducts  the  air  to  an  under- 
ground chamber,  where  it  can  be  warmed  if  necessary  by  passing 
over  hot  water  or  steam  pipes;  it  is  then  conducted  to  the  rooms 
above  by  means  of  tubes,  and  finally  escapes  above  the  roof 
through  tubes  surmounted  by  cowls  backed  to  the  wind. 


220  HYGIENE   AND    PUBLIC  HEALTH 

The  aspirating  action  of  the  wind  is  constantly  being  used  to 
ventilate  rooms  by  means  of  the  chimney.  With  a  frre  burning 
in  the  grate,  the  draught  up  the  chimney  is  increased  by  the 
aspiration  of  the  wind  when  the  top  of  the  chimney  is  above 
surrounding  buildings.  Even  when  there  is  no  fire  in  the  grate, 
it  will  usually  be  found  that  there  is  a  current  setting  up  the 
chimney.  Should  the  top  of  the  chimney  be  lower  than  sur- 
rounding structures,  the  wind  striking  these  and  then  descending 
will  often  cause  a  back-draught  and  a  smoky  chimney.  The 
remedy  is  evidently  to  carry  up  the  chimney  to  at  least  the  height 
of  the  surrounding  buildings.  A  suitable  cowl  surmounting  the 
chimney  may  prevent  or  mitigate  back-draught.  From  experi- 
ments carried  out  by  the  Royal  Sanitary  Institute  it  appears  that 
certain  forms  of  cowls  or  terminals  have  the  effect  of  increasing 
the  up  draught  in  air  shafts,  but  that  some  30  per  cent,  of  those 
forms  experimented  with  were  valueless  for  that  purpose.  It 
is  evident  that  on  dull  days,  when  the  atmosphere  is  still,  ventila- 
tion is  most  required,  and  that  then  such  air  shafts  surmounted 
by  cowls  or  terminals  are  of  little  value.  Another  cause  of 
smoky  chimneys  is  an  insufficient  supply  of  air  to  the  room.  To 
feed  the  fire,  air  is  drawn  down  the  chimney,  and  coming  down 
in  puffs,  it  causes  an  escape  of  smoke.  The  remedy  is  obtained 
by  making  a  suitable  inlet  for  fresh  air  into  the  apartment. 

Sometimes  it  is  found  that  the  smoke  escaping  from  one 
chimney  is  drawn  down  another  opening  close  by  and  on  the 
same  level.     In  such  a  case  one  of  the  chimneys  should  be  raised. 

The  movement  produced  by  inequality  in  density  or  weight 
of  contiguous  masses  of  air  at  different  temperatures  is  the 
natural  force  chiefly  relied  on  for  ventilating  the  interior  of  houses 
in  this  chmate.  This  force  is  naturally  chiefly  called  into  action 
in  cold  weather,  when  the  difference  between  the  internal  and 
external  temperature  is  considerable,  and  is  more  or  less  in  abey- 
ance in  summer,  when  the  temperature  outside  is  often  equal 
to,  or  even  greater  than,  that  of  the  house.  The  greater  this 
difference  of  temperature  and  the  difference  of  level  between 
the  aperture  for  the  entrance  of  cold  air  and  the  aperture  for  the 
exit  of  heated  air,  the  greater  will  be  the  velocity  of  the  entering 
air.  We  are  enabled  to  calculate  the  theoretical  velocity  by 
means  of  Montgolfier's  formula,  which  is  founded  on  the  dyna- 
mical law  that  the  velocity  in  feet  per  second  of  falling  bodies 
is  equal  to  eight  times  the  square  root  of  the  height  through 


AIR   AND    VENTILATION  221 

which  they  have  fallen.  In  this  case  the  height  fallen  is  repre- 
sented by  the  difference  in  pressure  of  the  air  inside  and  outside 
the  house,  which  is  equal  to  the  difference  of  level  between  the 
apertures  of  entrance  and  exit  multiplied  by  the  expansion  of 
air  caused  by  the  difference  in  temperature  inside  and  outside. 

„        9    V  /(/;-//')   {t-t')  ,      .        .      , 

"  -  o   \  ^  velocity  m  feet  per  second, 

491 

where  h=  height  in  feet  of  aperture  of  exit  from  ground; 
,,      //'=  .,         ,,  entrance  from  ground ; 

t  =  temperature  of  air  inside  in  degrees  Fahr. ; 
,,      t'  =  ,,  „  outside  in  degrees  Fahr. 

In  practice  an  allowance  for  friction  of  J  or  J  must  often  be 
made.  As  it  is  impossible  to  tell,  with  any  degree  of  accuracy, 
what  allowance  must  be  made  for  friction  in  any  given  instance, 
the  formula  is  little  employed  in  actual  practice,  and  the  anemo- 
meter {v.  page  229)  is  preferred.  If  the  area  of  the  inlet  opening 
is  known,  the  amount  of  air  entering  the  room  in  a  minute  or 
an  hour  can  easily  be  calculated  by  multiplying  the  velocity  of  the 
entering  air  by  the  area  of  the  inlet  expressed  as  square  feet,  the 
result  being  the  number  of  cubic  feet  entering. 

In  a  room  as  usually  constructed  with  sash  windows  and  with 
a  fire-place  and  chimney,  but  without  any  special  means  of  venti- 
lation, when  a  fire  is  burning  in  the  grate  the  fresh  air  entering  the 
room  gets  warmed  as  it  approaches  the  fire,  and  part  ascends  the 
chimney  flue  while  part  rises  to  the  ceiling.  Cold  air  from  outside 
will  then  enter — if  the  windows  are  closed — under  the  door,  under 
the  skirting  boards,  between  the  sashes  of  the  window,  and 
through  any  other  chinks  or  apertures  due  to  loose  fittings. 
The  bricks  and  plaster  of  the  walls  are  also  porous  to  a  certain 
extent,  and  if  uncovered  by  paint  or  wall-paper  will  admit  a  small 
quantity  of  air.  Thus  a  large  volume  of  air  may  be  entering  a 
room  in  cold  weather  when  the  fire  is  burning,  although  there 
are  no  visible  inlets;  and  the  amount  of  air  thus  supplied  may 
be  sufficient  for  the  needs  of  two  or  three  persons  if  it  were  pro- 
perly distributed.  But  such  is  not  the  case.  The  cold  air, 
which  enters  chiefly  near  the  floor,  takes  as  straight  a  course 
as  possible  to  the  fire-place,  often  producing  a  disagreeable 
draught  to  the  feet  of  the  occupants,  whilst  the  heated  and 
vitiated  air  near  the  ceiHng  is  left  undisturbed. 

In  this  country,  to  prevent  draughts  and  to  insure  a  thorough 


222 


HYGIENE    AND   PUBLIC    HEALTH 


distribution,  fresh  air  not  previously  warmed  should  be  admitted 
into  the  room  sHghtly  above  the  heads  of  the  occupants,  an 
upward  direction  being  given  to  it  so  that  it  may  rise  a  Uttle 
towards  the  ceiling,  mix  with  and  be  warmed  by  the  heated  air 
in  this  situation,  fall  gently  into  all  parts  of  the  room,  and  be 
gradually  removed  by  means  of  the  chimney  flue,  or  other  outlet 
— which  should  preferably  be  at  the  highest  part  of  the  room. 


Fig.  32. — Diagrammatic  Sketch  of  Various  Provisions  for 
Ventilation. 

A,  Sash  window  with  Hinckes-Bird's  arrangement.  B,  Hopper  sash-light 
falling  inwards.  C,  Louvred  outlets.  D,  Mackinnel's  ventilator. 
E,  Sheringham's  Valve.  F,  Tobin's  Tube  (showing  valve  open). 
G,  Ellison's  Conical  Bricks.  H  and  I,  Grid  ventilators  below  floor 
joists. 

Amongst  simple  contrivances  for  windows  by  which  these 
objects  may  be  attained  may  be  mentioned  Hinckes-Bird's 
method  (fig.  32),  now  so  well  known,  of  placing  a  solid  block  of 
wood  under  the  entire  length  of  the  lower  sash  frame  of  a  window, 
so  as  to  raise  the  top  rail  of  the  lower  sash  above  the  bottom  rail 
of  the  upper  sash.  By  this  means  the  air  is  admitted  between  the 
two  sashes  above  the  heads  of  the  occupants  of  the  room,  and 
is  given  an  upward  direction   towards  the  ceiling.     The  same 


AIR    AND    VENTILATION  223 

result  may  be  more  conveniently  obtained  by  the  use  of  a  deep 
beaded  sill,  which  permits  the  lower  sash  to  be  raised  without  any 
passage  of  air  under  it,  at  the  same  time  allowing  air  to  enter 
between  the  two  sashes.  Holes  bored  in  a  perpendicular 
direction  in  the  bottom  rail  of  the  upper  sash,  louvrcd  panes  to 
replace  one  of  the  squares  of  glass,  an  arrangement  for  allowing 
one  of  the  squares  of  glass,  provided  with  side  checks,  to  fall 
inwards  upon  its  lower  border,  or  a  double  pane  of  glass  in  one 
square,  open  at  the  bottom  outside,  and  at  the  top  inside, 
all  effect  the  same  purpose  and  are  simple  and  inexpensive 
contrivances.  Cooper's  ventilator,  which  consists  of  a  series 
of  apertures  in  the  glass  of  a  window  pane,  arranged  in  a  circle 
and  capable  of  being  more  or  less  completely  closed  by  a  circular 
glass  disc,  also  with  apertures,  and  movable  on  a  central  pivot, 
does  not  admit  the  air  in  an  upward  direction,  but  breaks  it 
up  into  a  number  of  divided  currents,  and  thus  lessens  the 
tendency  to  draught.  The  same  object  can  be  obtained  by 
placing  wire  gauze  or  mushn  over  any  inlet  opening. 

A  very  useful  form  of  window  ventilator  is  that  known  as  the 
"  hopper  inlet."  A  glazed  frame,  the  same  width  as  the  window, 
and  about  i8  inches  deep,  is  fixed  to  the  lower  sill  by  its  lower 
border,  and  is  made  to  fall  inward,  moving  in  a  frame  which  has 
side  cheeks  to  obviate  lateral  movements  of  air.  When  the 
lower  sash  is  raised,  air  enters,  and  is  deflected  upwards  in  a 
slanting  direction  by  the  glazed  hopper.  When  the  window  is 
shut,  the  hopper  is  pushed  up  so  as  to  be  parallel  with  the  sash, 
and,  being  glazed,  there  is  no  loss  of  light.  These  hopper  inlets 
are  found  to  be  very  useful  where  radiators  are  fixed  on  an 
external  wall  under  a  window,  as  they  allow  cool  air  to  pass  in 
and  mix  with  the  heated  column  of  air  rising  from  the  radiator. 

Hopper  inlets  are  also  used  above  the  sash  frame  of  a  window. 
Here  the  air  is  admitted  near  the  level  of  the  ceiling,  and  cold 
draughts  may  be  experienced,  owing  to  the  air  descending  before 
it  has  become  mixed  and  warmed  with  the  air  of  the  apartment. 
The  hoppers  should  be  glazed  and  provided  with  side  checks. 
They  are  often  used  in  hospitals  and  other  institutional  buildings, 
where  it  is  undesirable  to  have  inlets  nearer  the  floor,  owing  to 
beds  or  seats  near  the  external  walls. 

The  most  generally  used  wall  inlet  ventilators  are  Sheringham's 
valve,  Tobin's  tube,  and  Ellison's  conical  bricks. 

In  the  Sheringham  valve  (fig.  32)  air  passes  through  the  wall 


224  HYGIENE    AND    PUBLIC    HEALTH 

by  means  of  a  perforated  iron  plate,  and  is  then  directed  upwards 
by  a  valved  plate  with  side  checks,  which  projects  into  the  room, 
and,  being  hinged  at  its  lower  border,  is  capable  of  being  more 
or  less  completely  closed  by  a  balance  weight.  The  usual  size 
of  the  inlet  opening  in  these  ventilators  is  9  inches  by  3,  giving 
an  area  of  27  square  inches. 

In  Tobin's  tube  (fig.  32)  air  is  introduced  from  the  outside  at 
the  floor  level  through  a  perforated  plate,  and  then  passes  up  a 
vertical  tube  to  a  height  of  from  4  to  6  feet  above  the  floor.  After 
escaping  from  the  tube,  the  current  of  air  ascends  more  or  less 
vertically  for  a  short  distance,  before  it  begins  to  spread  out 
and  mix  with  the  air  of  the  room.  In  these  two  contrivances 
(Tobin's  tube  and  the  Sheringham  valve)  the  entering  air  may  be 
filtered  through  muslin  or  cotton  wool,  or  made  to  impinge  upon 
a  tray  containing  water,  and  so  deposit  its  sooty  particles — a 
procedure  often  advisable  in  smoky  towns. 

Tobin's  tubes  and  other  inlet  and  outlet  ventilators  should  be 
made  accessible  in  all  their  parts  for  cleansing,  as  they  quickly 
become  lined  internally  with  dirt  and  adherent  filth.  Tobin's 
tubes  should  be  made  detachable  from  the  external  wall  opening 
for  this  purpose. 

ElHson's  bricks  (fig.  32)  are  pierced  with  conical  holes,  the  small 
opening,  ]  inch  in  diameter,  being  placed  outside  the  building, 
whilst  the  larger  opening,  ij  inches  in  diameter,  is  placed  inside. 
The  thickness  of  the  brick  is  4I  inches.  The  air  passing  through 
these  conical  apertures  becomes  distributed  over  a  gradually  in- 
creasing area,  and  in  this  way  its  slow  entrance  is  rendered  imper- 
ceptible and  unproductive  of  draught.  These  bricks  may  be 
used  for  ventilating  drill  halls,  gymnasia,  stables,  and  cowsheds. 

All  the  inlet  ventilators  described  are  intended  to  utilize  the 
movements  produced  by  contiguous  masses  of  air  at  unequal  tem- 
peratures. For  this  reason  they  should  be  protected  as  far  as 
possible  from  the  perflating  action  of  the  wind.  This  cannot, 
however,  always  be  done ;  and  when  a  strong  cold  wind  is  blowing 
into  a  ventilator,  even  of  the  most  approved  sort,  a  most  un- 
bearable draught  may  be  the  result.  To  obviate  this,  there 
should  be  some  means  of  controlling  the  amount  of  entering  air 
by  partially  closing  the  ventilator,  and  in  many  cases  the  venti- 
lator must  be  closed  altogether.  Sheringham's  valve,  Tobin's 
tube,  and  louvred  inlets,  fulfil  these  requirements  very  satis- 
factorily.    It  is  often  found  that  inlet  ventilators  are  acting  as 


AIR  AND   VENTILATION  225 

outlets  for  the  escape  of  air,  when  fresh  air  is  entering  a  room 
from  other  sources.  This  cannot  be  obviated,  nor,  indeed,  is  it 
necessary.  All  that  can  be  done  is  to  place  the  inlets  in  the  best 
possible  position  for  distributing  the  entering  air  throughout  the 
apartment  without  causing  a  draught,  and  to  close  up  all  such 
sources  of  entering  air  as  are  productive  of  draughts. 

The  usual  outlet  for  the  vitiated  air  of  a  room  is  the  chimney 
Hue;  and  this,  for  an  ordinary  medium-sized  sitting-room,  with 
a  lire  burning  in  the  grate,  is  sufficient  for  three  or  four  people 
provided  no  gas  is  alight,  or  the  gas  lamp  has  its  own  special 
ventilating  arrangement.  With  an  ordinary  fire,  from  10,000  to 
15,000  cubic  feet  of  air  are  drawn  up  the  chimney  in  an  hour, 
the  current  being  generally  from  3  to  6  feet  per  second;  but  a 
large  fire  will  often  induce  a  current  of  8  or  9  feet  per  second. 

Heated  air  rises  to  the  top  of  a  room;  therefore  the  proper 
place  to  admit  of  the  vitiated  air  escaping  is  in  or  near  the  ceihng. 

Neil  Arnott's  or  Boyle's  valves,  in  which  a  metal  frame  supports 
small  talc  plates,  which  open  into  the  chimney  flue  near  the  ceiling, 
are  sometimes  used  as  outlets  for  foul  air.  They  permit  air  to 
pass  from  the  room  into  the  flue,  but  the  talc  plates  prevent  its 
return;  the  objections  to  their  use  are  that  they  occasionally 
permit  the  reflux  of  smoke  into  the  room,  and  the  movements  of 
the  plates  produce  a  slight  clicking  noise.  If  exit  shafts  other 
than  the  chimney  flue  are  provided,  they  should  be  short  and 
straight,  and  capable  of  being  readily  cleansed ;  otherwise  friction, 
and  loss  of  heat  by  passage  of  the  air  through  an  exposed  tube, 
will  stop  the  current  altogether,  or  reverse  it,  causing  a  back- 
draught.  The  escaping  air  must  have  its  temperature  kept  up, 
or  it  cannot  escape. 

One  of  the  best  methods  of  attaining  this  object,  which  might 
be  put  into  practice  in  all  new  buildings,  is  to  construct  a  shaft 
at  one  side  of  or  surrounding  the  chimney  flue,  with  an  inlet 
near  the  ceiUng  of  the  room,  and  the  outlet  at  the  level  of  the 
chimney  top.  The  air  escaping  from  the  room  will  then  have 
its  temperature  kept  up  by  contact  with  the  chimney  flue,  thus 
aiding  the  up  draught,  whilst  the  risk  of  reflux  of  smoke  will  be 
avoided.  The  air  flues  may  be  moulded  in  the  same  piece  of  fire 
clay  as  the  smoke  flue;  but  those  from  different  rooms  should 
not  be  connected  in  any  way,  or  foul  air  from  one  room  might 
pass  into  another. 

The  combustion  of  gas  may  be  made  a  very  effective  means 

15 


226  HYGIENE   AND   PUBLIC   HEALTH 

of  getting  rid  of  foul  air.  It  has  been  found  by  experiment  that 
the  combustion  of  i  cubic  foot  of  coal  gas  causes  the  discharge  of 
1,000  cubic  feet  of  air.  An  extraction  shaft  may  be  placed  over 
a  gas  lamp  or  chandelier ;  and  by  means  of  a  Benham's  ventilating 
globe  light,  or  a  Mackinnel's  ventilator,  slightly  warmed  fresh  air 
may  be  admitted  at  the  same  time  as  foul  air  is  extracted. 

Mackinnel's  ventilator  (fig.  32)  is  very  useful  for  a  room  which 
has  no  other  apartment  over  it.  Two  tubes,  one  inside  the  other, 
are  carried  through  the  ceiling  or  roof  of  the  building.  The  inner 
one,  which  is  for  the  extraction  of  foul  heated  air,  projects  outside 
above  the  outer,  and  inside  also  below  it.  At  its  lower  end  a 
broad  circular  horizontal  rim  is  attached  to  the  inner  tube  which 
deflects  the  air  entering  by  the  outer  tube,  and  causes  it  to  pass 
for  a  short  distance  parallel  to  the  ceiling  before  falling  into  the 
room,  as  otherwise  the  fresh  air  would  be  drawn  round  into  the 
inner  or  exit  shaft.  The  gas  burners  or  lamps  used  to  light 
the  room  are  placed  immediately  under  the  inner  tube  of  this 
ventilator.  The  inner  or  extraction  tube  should  have  its  top 
protected  by  a  cover  or  cowl,  to  prevent  the  wind  blowing  down 
and  the  entrance  of  rain,  which  by  evaporation  might  so  cool  the 
escaping  air  as  to  cause  it  to  be  heavier  than  the  air  of  the 
apartment.  The  entering  air  will  be  slightly  warmer  by  its 
passage  over  the  heated  extraction  shaft.  The  area  of  the  outer 
tube  for  the  passage  of  fresh  air  should  be  equal  to,  or  slightly 
larger  (for  there  is  more  friction  to  overcome)  than  the  area 
of  the  inner  tube  for  exit  of  foul  air.  Mackinnel's  ventilator 
is  well  adapted  for  large  buildings,  as  schools,  churches,  halls, 
etc.,  which  have  no  upper  floors  or  stories.  Benham's  ventilating 
globe  light,  as  its  name  expresses,  combines  ventilation  and 
lighting;  shghtly  warmed  fresh  air  is  admitted,  and  foul  air  is 
extracted  along  with  the  products  of  combustion.  In  theatres 
sunlight  burners  are  largely  used;  they  aid  the  extraction  of  foul 
air,  but  do  not  admit  fresh  air. 

In  Pott's  method  of  ventilation  a  hollow  metalhc  perforated 
cornice  is  divided  into  an  upper  and  lower  half  by  means  of  a 
horizontal  plate.  Pure  air  enters  the  room  through  the  lower 
half,  which  communicates  with  the  outside  air,  and  foul  air  is 
extracted  through  the  upper  half,  which  opens  into  the  chimney. 

Extraction  shafts,  like  inlet  openings,  are  liable  to  have  their 
action  reversed  under  certain  circumstances.  When  the  wind  is 
blowing  down  upon  them,  when  rain  gets  in,  when  the  escaping 


AIR    AND   VENTILATION  227 

air  is  subject  to  niucli  cooling  in  an  exposed  sliait,  or  when  there 
are  more  outlets  than  one  in  a  room,  one  predominating  over  the 
others,  down  draughts  are  likely  to  occur.  This  most  frequently 
happens  when  the  draught  up  the  chimney  is  very  great  from 
there  being  a  large  fire  burning;  then  there  is  a  tendency  for 
every  other  opening  into  a  room  to  become  an  inlet.  Also,  when 
the  wind  is  blowing  down  an  exit  shaft  or  chimney  fiue,  the 
windows  or  inlet  ventilators  may  become  outlets.  These  matters 
can,  however,  generally  be  regulated  by  attention  to  the  facts 
and  principles  which  have  been  already  laid  down  as  a  guide  to 
proper  ventilation. 

It  will  be  convenient  to  mention  in  this  place  some  facts  with 
regard  to  loss  of  velocity  in  air  shafts  by  friction.  The  actual 
loss  can  in  some  cases  be  determined  by  calculating  the  theoretical 
velocity  in  an  air  shaft  by  Montgolfier's  fornmla,  and  then  ascer- 
taining practically  by  means  of  a  current  meter  or  anemometer 
the  actual  rate  at  which  the  air  is  issuing  or  escaping.  The  differ- 
ence represents  the  loss  due  to  friction;  but  allowance  must  of 
course  be  made  for  disturbing  forces,  such  as  the  perflating  or 
aspirating  action  of  the  wind.  Contrasting  two  similar  tubes  of 
equal  sectional  area,  the  loss  by  friction  will  be  directly  as  the 
length  of  the  tube.  If  the  two  similar  tubes  are  of  unequal  size, 
the  loss  by  friction  is  inversely  as  the  diameter  of  the  cross  section 
in  each. 

When  two  tubes  are  dissimilar  in  shape,  the  loss  by  friction 
is  inversely  as  the  square  roots  of  the  sectional  areas.  A  circle 
is  a  figure  which  includes  the  greatest  area  within  the  smallest 
periphery;  thus,  if  there  are  two  tubes,  one  of  which  is  circular 
in  section  and  the  other  square,  but  having  the  same  area  (i  square 
foot),  the  loss  by  friction  is  directly  as  the  periphery,  and  in 

this  case  is  as       ,   the  periphery  of  the  square  being  4  feet  and 

4 
of  the  circle  3^  feet.  Every  right  angle  in  a  bent  shaft  diminishes 
the  velocity  of  the  current  one-half.  It  will  thus  be  seen  that 
air  shafts  should  preferably  be  circular  in  section,  short  and 
straight,  so  as  to  diminish  the  loss  by  friction  as  far  as  possible. 
The  absurdity  of  ventilating  soil  pipes  and  drains  by  narrow 
pipes,  I  or  2  inches  in  diameter,  of  great  length,  and  bent  on 
themselves  often  to  a  right  angle,  is  apparent  from  the  above 
statements.  The  ventilation  of  drains  is  always  difficult  to  estab- 
lish; carried  out  by  such  methods  it  becomes  an  impossibihty. 


228  HYGIENE    AND    PUBLIC    HEALTH 

Ventilating  appliances  whose  object  is  the  supply  of  artificially 
warmed  air  will  be  considered  separately  in  the  chapter  on 
Heating  and  Warming. 

Artificial  Ventilation. — Under  this  heading  are  usually  described 
methods  of  extraction  of  air  from  inhabited  buildings  by  means 
of  heat,  steam,  or  fans;  and  methods  of  propulsion  of  air  into 
buildings  by  mechanical  means.  It  has  been  found  convenient 
to  describe  under  natural  ventilation  of  rooms  the  ventilating 
effects  produced  by  fires  and  chimneys  in  ordinary  rooms;  and 
the  extractive  properties  of  gas  hghts  have  also  been  alluded  to, 
although,  properly  speaking,  fires  and  gas  are  artificial  means  of 
ventilation. 

The  fire  and  chimney  of  an  ordinary  sitting-room  are  types 
of  the  methods  used  on  a  larger  scale  for  extraction  by  heat. 
The  principle  is  the  same  in  all,  and  depends  on  the  heating  of 
a  column  of  air  in  an  extraction  shaft,  which,  being  thus  made 
lighter,  ascends  ;  as  long  as  the  heat  is  applied,  a  continuous 
current  of  air  towards  the  shaft  is  produced,  which  in  its  turn  being 
heated,  ascends  and  escapes,  to  be  replaced  by  more  from  below. 

It  is  in  this  way  that  some  mines  are  ventilated.  The  under- 
ground workings  and  galleries  of  the  mine  are  connected  with 
two  large  shafts — an  upcast  shaft  and  a  downcast  shaft,  usually 
from  8  to  12  feet  in  diameter,  leading  to  the  open  air — when  air 
is  made  to  pass  down  the  downcast  or  intake  shaft,  it  has  to  travel 
through  all  the  workings  of  the  mine  before  it  can  escape  by  the 
upcast  or  return  shaft. 

The  power  which  produces  this  continued  movement  of  air 
may  safely  be  supplied  in  some  mines  by  a  furnace  at  the  bottom 
of  the  upcast  shaft  exerting  an  extractive  force  by  the  heated 
column  of  air,  as  previously  described.  But  in  most  mines  the 
extractive  force  is  exerted  by  means  of  a  powerful  rotatory 
exhaust  fan  placed  at  the  top  of  the  upcast  shaft;  such  fans  can 
be  made  to  propel  some  12,000  cubic  feet  of  air  per  minute. 
Numerous  doors  and  partitions  are  necessary  in  the  galleries 
and  workings  in  order  to  make  the  air  traverse  the  whole  length 
of  these,  and  prevent  it  taking  short  cuts.  An  enormous  volume 
of  fresh  air  must  be  passed  through  a  mine  in  the  course  of  every 
hour  in  order  to  supply  the  quantity  necessary  for  the  respiration 
of  the  men  and  ponies  employed  underground,  and  to  withdraw  the 
products  of  combustion  of  hghts  (lamps  and  candles)  and  agents 
used  for  blasting,  and  to  replace  these  injurious  gases  by  pure  air. 


AIR    AND    VENTILATION  229 

Where  fire  damp  (CH^)  is  evolved  from  the  strata  cut  throii.cjh, 
the  ventilation  must  be  exceptionally  good,  in  order  to  dilute 
this  gas  sufficiently  to  prevent  its  forming  an  explosive  mixture 
with  atmospheric  oxygen.  The  same  may  be  said  with  regard 
to  the  evolution  of  carbonic  acid  from  the  rocks  underground, 
which  so  frequently  takes  place.  This  gas  must  not  be  allowed 
to  form  much  over  i  per  cent,  of  the  underground  air,  or  its 
asphyxiating  properties  will  be  exerted  on  all  animal  life  within  its 
influence.  The  injurious  effects  produced  by  gunpowder  blast- 
ing are  no  longer  necessary  evils  in  the  life  of  the  collier  or  coal 
miner  since  the  introduction  of  cartridges  made  of  quickhmc, 
which  swell  up  from  slaking  when  water  is  run  over  them,  and 
exert  their  action  without  producing  any  gas  at  all.  By  the 
use  of  such  cartridges  there  is,  besides,  no  risk  of  explosion 
from  ignition  of  fire  damp  or  of  coal  dust.  Other  substitutes  for 
explosives  in  fire  damp  collieries  are  plugs  of  dry  wood,  which 
swell  when  wetted,  wedges  worked  by  hydraulic  pressure, 
and  cartridges  containing  compressed  air  at  extremely  high 
pressures. 

Dynamite  is  now  largely  used  instead  of  gunpowder,  as  it 
is  more  powerful,  may  be  used  under  water,  and  requires  no 
hard  tamping.  It  is  a  mixture  of  nitro-glycerine  (C3H53(NO.,) 
and  infusorial  earth  or  kieselguhr.  Carbonic  oxide  is  not  one 
of  the  products  of  its  explosion  under  pressure;  and  hence 
its  superiority  to  gunpowder,  in  which  carbonic  oxide  forms 
7|  per  cent,  of  the  explosive  gases.  There  is  besides  no  forma- 
tion of  sulphuretted  hydrogen  and  marsh  gas  when  dynamite  is 
exploded,  whereas  these  gases  form  respectively  about  2  per  cent, 
of  the  total  gases  resulting  from  gunpowder  explosion.  Carbonic 
acid  and  nitrogen  form  nearly  the  entire  bulk  of  the  gases  result- 
ing from  nitro-glycerine  explosion  in  closed  vessels.  Nitrated 
gun-cotton  and  blasting  gelatine  (nitro-cotton  and  nitro-glycerine) 
are  also  superior  to  gunpowder  for  the  same  reasons,  carbonic 
acid  and  nitrogen  forming  almost  the  entire  bulk  of  the  gases 
generated  when  these  substances  are  exploded  under  pressure.^ 

Notwithstanding  the  importance  of  an  abundant  supply  of 
pure  air  to  all  the  workings  of  a  mine,  it  has  been  found  impos- 
sible by  the  Government  inspectors  to  insist  even  on  so  low  a 
standard  of  purity  as  that  indicated  by  0-25  per  cent,  of  CO.,  in  the 

*  Enrvdopcrdia  Britannica,  article  on  "  Mining,"  by  C.  Le  Neve  Foster, 
D.S...    F.R.S. 


230  HYGIENE    AND    PUBLIC    HEALTH 

air.  It  is  maintained  that  in  every  mine  at  least  6,000  cubic  feet 
of  fresh  air  per  hour  should  be  supplied  for  every  man  employed 
below,  for  if  this  quantity  is  much  reduced  there  is  a  serious 
diminution  in  the  amount  of  work  performed  by  the  men,  so 
that  even  commercially  it  pays  employers  to  have  adequate 
ventilation.  In  mines  where  fire  damp  or  choke  damp  is  evolved, 
the  amount  of  fresh  air  supplied  should  exceed  this  figure.  The 
furnace  at  the  bottom  of  the  upcast  shaft,  or  the  speed  at  which 
the  fan  is  driven,  must  be  regulated  according  to  the  number 
of  men  employed  and  the  amount  of  work  that  is  going  on  at 
any  time  below  ground. 

It  has  recently  been  suggested  that  coal  mines,  where  there  is 
a  danger  of  explosions  being  caused  by  collections  of  fire  damp 
(CH4)  or  coal  dust,  should  be  supplied  with  air  containing  onl}^ 
17-5  per  cent,  of  oxygen — an  atmosphere  which,  it  is  said,  will 
not  support  combustion,  and  would,  therefore,  be  an  effectual 
preventative  of  explosions.  The  miner  could  live  and  breathe 
in  an  atmosphere  containing  only  17-5  instead  of  21  per  cent,  of 
oxygen,  if  the  air  was  otherwise  pure  and  free  from  deleterious 
gases.  Dr.  Leonard  Hill  has  stated  that  if  a  coal  mine  were 
ventilated  with  air  containing  17  per  cent,  of  oxygen,  in  suffi- 
cient volume  to  keep  the  miners  cool  and  fresh,  not  only  would 
explosions  be  guarded  against,  but  the  mines  could  be  safely 
worked  and  illuminated  with  electricity,  and  miner's  nystagmus 
prevented.  It  has  yet  to  be  demonstrated  that  it  would  be  a 
practicable  measure  to  supply  coal  mines  with  air  containing  the 
reduced  amount  of  oxygen,  and  that  the  miners  would  not  suffer 
in  health  or  working  efficiency  from  living  under  such  conditions 
of  atmosphere. 

Public  halls,  hospitals,  and  other  large  buildings,  are  some- 
times ventilated  on  the  extraction  principle.  Shafts  for  the 
escape  of  vitiated  air  lead  from  the  different  rooms  and  open  into 
the  chimney  just  over  the  furnace.  The  air  from  these  shafts 
should  not  be  used  to  supply  the  fire  or  furnace,  but  should  always 
open  into  the  flue  just  above  it,  where  the  draught  is  greatest. 

The  column  of  air  in  an  extraction  shaft  may  be  heated  by 
steam  or  hot  water  pipes,  instead  of  by  a  fire.  This  is  the  plan 
adopted  at  the  Hopital  Lariboisiere  in  Paris.  The  extraction 
shaft  is  heated  throughout  the  greater  part  of  its  length  by 
spiral  hot  water  pipes  coming  from  a  btiiler  in  tlie  basement. 
These  hot  water  pipes  arc  also  carried  into  the  wards,  where 


AIR    AND    VENTILATION  23I 

they  arc  coiled  so  as  to  warm  the  fresh  air  enteriiif^^  from  with- 
out; they  then  return  to  the  boiler,  and  thus  complete  the  circuit. 
The  tubes  from  the  wards  for  the  escape  of  foul  air  open  into  the 
bottom  of  the  extraction  shaft.  In  summer  the  circulation  of 
hot  water  in  the  pipes  in  the  wards  is  stopped,  the  circuit  being 
completed  by  return  pipes  from  the  top  of  the  extraction  shaft, 
so  that  the  ventilation  continues,  but  the  air  entering  the  wards 
is  not  artificially  warmed. 

The  column  of  air  in  an  extraction  shaft  may  be  heated  by 
gas  instead  of  by  fire;  but  this  method  is  more  suitable  for  the 
smaller  tubes  used  as  exit  shafts  in  ordinary  sized  dwelling-rooms. 
Foul  air  may  also  be  extracted  by  passing  a  steam  jet  into  a 
chimney  or  upcast  shaft.  The  shafts  for  the  escape  of  foul  air 
must  open  into  the  extraction  shaft  below  the  steam  jet.  The 
cone  of  steam  emitted  from  a  boiler  is  said  to  set  in  motion  and 
drive  before  it  a  body  of  air  ecjual  to  217  times  its  own  bulk. 

On  board  steamships  and  men-of-war  it  has  been  found  that 
very  effective  ventilation  can  be  obtained  by  causing  the  furnaces 
to  extract  the  air  from  all  parts  of  the  ship  through  special  shafts. 
By  this  means  also,  if  the  boilers  and  steam  apparatus  are 
enclosed  in  iron  casings,  as  far  as  possible,  within  which  the 
air  shafts  open,  the  temperature  of  the  stokehole  is  greatly 
reduced. 

Some  of  the  chief  objections  to  the  method  of  extraction  by 
heat  are:  (i)  Where  the  heat  is  produced  by  a  furnace,  it  is 
most  difficult  to  keep  this  at  a  constant  temperature,  conse- 
quently the  draught  is  often  very  irregular.  This  difficulty  is  not 
encountered  where  the  extraction  shaft  is  heated  by  steam,  gas,  or 
hot  water  pipes,  or  where  the  air  in  it  is  forced  upwards  by  steam. 
(2)  In  all  cases  where  a  number  of  air  conduits  from  rooms 
at  different  distances  open  into  an  extraction  shaft,  there  is  a 
great  tendency  to  create  powerful  currents  from  rooms  that  are 
near,  and  have  short  conduits  leading  from  them;  whilst  from 
the  distant  apartments  with  long  and  perhaps  much  curved  con- 
duits the  current  may  be  very  slight,  or  even  nil.  This  difficulty 
may  to  a  certain  extent  be  overcome  by  increasing  the  diameter 
of  the  longer  pipes  so  as  to  reduce  the  friction,  and  by  bending 
the  shorter  pipes  so  as  to  increase  it;  but  in  practice  it  is  a 
rather  serious  drawback.  (3)  When  air  is  drawn  out  of  a  room 
it  is  somewhat  difficult  to  control  the  entrance  of  fresh  air  to 
supply  its  place,  especially  with  regard  to  its  point  of  entry  and 


232  HYGIENE    AND    PUBLIC   HEALTH 

its  exclusion  from  places  such  as  water-closets,  from  which  it  is 
most  desirable  that  no  air  should  be  taken. 

In  the  ventilation  of  factories,  steam  may  often  be  economically 
and  usefully  appHed  as  the  extraction  force,  but  extraction  by 
fans  has  also  been  largely  used,  and  presents  considerable  advan- 
tages, as  the  amount  of  draught  can  be  nicely  regulated  by 
altering  the  speed  (the  number  of  revolutions  per  minute)  at 
which  the  fan  is  driven.  It  is  especially  in  the  textile  trades — 
in  the  cotton,  woollen,  silk,  worsted,  and  flax  factories — that 
ventilation  is  most  urgently  needed.  In  many  of  the  processes 
of  these  manufactures  the  work  is  not  only  carried  on  in  clouds 
of  dust,  but  also  in  greatly  heated  atmospheres  which  are  satur- 
ated with  moisture,  this  being  necessary  in  some  instances  to 
the  proper  performance  of  the  work.  To  carry  off  the  floating 
particles  of  dust  it  is  necessary  to  induce  a  powerful  current  in  the 
exit  shaft,  so  that  the  air  may  be  drawn  in  as  if  to  a  vortex.  In 
some  cases  the  opening  into  the  exit  shaft  may  be  in  the  centre 
of  the  room;  but  it  is  more  often  advisable  to  carry  the  dust 
away  as  soon  as  it  originates,  and  before  it  can  mix  with  the 
general  air  of  the  apartment. 

Thus,  in  the  wool  sorting  trade,  each  bench  on  which  the 
wool  is  sorted  has  an  opening  leading  by  means  of  a  pipe  into 
the  extraction  shaft,  at  the  extremity  of  which  the  exhaust  fan 
is  working.  When  the  wool  is  being  shaken,  the  dust,  amongst 
which  may  be  the  spores  of  Bacillus  anthracis,  is  drawn  into  the 
tube,  and  does  not  mix  with  the  air  which  is  inhaled  by  the 
workmen.  The  dust  is  then  driven  into  settling  chambers, 
where  it  is  damped  by  steam  jets,  and  so  deposited  can  be  col- 
lected and  burnt.  In  silk  dressing  processes,  air  tubes  are 
placed  above  the  machinery  with  dependent  hooded  openings, 
which  cover  the  area  of  dust  production  and  quickly  remove 
the  dust;  such  flues  either  lead  into  the  chimney  flue,  or  have 
a  powerful  draught  created  in  them  by  means  of  fans  placed 
towards  the  end  of  the  shaft  which  leads  from  them  to  the  outside 
air.  In  the  dry  grinding  processes  of  the  metal  trades,  the  air 
tubes  are  placed  level  with  the  grindstones  and  have  openings 
opposite  each  stone,  in  such  positions  as  to  catch  the  dust,  as  it  is 
driven  off,  and  carry  it  away  at  once.  The  best  material  for 
the  exit  shafts  and  tubes  is  galvanized  sheet  iron,  as  it  can  be 
made  into  smooth  circular  pipes.  Arrangements  must  be  made 
to  provide  that  the  draught  from  the  benches,  or  the  workrooms 


AIR    AND    VENTILATION 


233 


nearest  the  fan,  is  not  so  great  as  to  prevent  tlie  shafts  at  a  dis- 
tance from  working  properly. 

A  very  convenient  form  of  fan  is  that  known  as  the  Blackman 
Air  Propeller;  it  can  be  used  for  exhaustion  (vacuum  ventilation) 
or  for  propulsion  (plenum  ventilation),  and  is  very  powerful  in 
its  action,  its  vanes  being  large  and  curved.  Another  good  form 
of  fan,  which  is  noiseless  in  its  working,  is  that  known  as  the 
Sturtevant  "  blower."  They  can  be  driven  by  a  gas  or  steam 
engine,  by  water  or  electricity,  and  are  employed  for  removing 
dust,  foul  air,  or  fumes  and  steam.     When  used  for  propelling 


Fig.  33. — Sturtevant  Pneumatic  Dust  Collecting  System. 


air  into  a  building,  the  rate  of  movement  in  the  main  conduit 
should  not  exceed  5  feet  per  second,  and,  where  delivered  into 
the  rooms,  not  more  than  i-|  or  2  feet  per  second.  The  sectional 
area  of  the  air  shafts  should  be  at  least  equal  to  that  of  the  fan. 
so  as  to  reduce  resistance  by  friction.  The  warmed  fresh  air 
should  be  delivered  by  the  pipes  into  the  rooms.  Special  exit 
shafts  are  not  always  necessary,  and  those  existing  near  the 
ceiling  should  be  closed.  The  air  finds  its  way  out  through 
fire-places,  doors,  windows,  or  the  mnumerable  minute  apertures 
by  which  every  room  communicates  with  the  exterior.  In  the 
"  plenum  "  system,  windows,  etc.,  are  kept  closed,  so  that  the 


234 


HYGIENE    AND    PUBLIC    HEALTH 


air  bcini^  constantly  driven  into  the  rooms  is  under  a  slight 
pressure  which  causes  it  to  escape  through  the  exit  opening  or 
openings  communicating  with  special  exit  shafts.  These  exit 
openings  should  be  low  down  in  the  rooms  or  workshops,  and 
principally  on  the  same  side  of  the  room  as  ihe  inlets,  so  as  to 
cause  the  incoming  air  to  circulate  thoroughly  before  it  escapes. 
Mechanical  ventilation  by  means  of  fans  is  now  much  used  in 


PI 


er^a^r^ 


G^y&te 


no. 


Fig.  34. 


public  halls  and  restaurants,  and  is  advocated  for  school  class- 
rooms. 

The  objections  to  the  propulsion  or  "  plenum  "  system  of 
ventilating  buildings  is  that  experience  shows  that  air  which 
has  travelled  through  lengthy  shafts  and  special  air  chambers 
has  lost  its  freshness  and  is  liable  to  cause  lassitude  and  a  feeling 
of  depression  amongst  those  who  habitually  come  under  its  influ- 
ence. Chemical  and  bacterioscopic  examination  may  demon- 
strate the  purity  of  such  air,  but  none  the  less  there  is  reason 
to  believe  that  in  such  air  the  vitalizing  principle  characteristic 
of  really  fresh  air  is  diminished.  The  essential  distinction  be- 
tween town  and  country  air  is  likewise  probably  due  to  a  diniinu- 


AIR    AND    VENTILATION  235 

tion  or  deterioration  of  the  unknown  vitalizing  principle  ])rescnt 
in  a  purely  natural  atmosphere.  The  very  artificiality  of  the 
plenum  system,  which  permits  of  the  air  supply  being  regulated 
with  great  nicety  as  to  volume,  temperature,  moisture,  etc.,  robs 
it  at  the  same  time  of  the  refreshing  qualities  so  important  for 
the  maintenance  of  a  good  standard  of  health.  Open  windows 
and  direct  ventilation  throiigh  the  external  walls  of  a  building 
may  cause  draughts  and  irregularities  of  temperature,  luit  such 
methods  appear  to  be  more  healthful  for  hospitals  and  buildings 
of  the  factory  and  domestic  class,  which  are  more  or  less  con- 
tinuously occupied,  than  the  artificial  systems  of  ventilation. 
For  theatres,  churches,  concert  halls,  etc.,  where  large  numbers 
are  collected  for  limited  periods  only,  artificial  systems  of  ventila- 
tion find  their  best  application;  but  in  the  plenum  system  the 
permanently  closed  windows  constitute  a  very  bad  object-lesson 
to  scholars  at  school. 

But  ventilation  by  propulsion  (plenum  method)  presents 
several  advantages.  The  amount  of  air  delivered  and  the  rate 
of  movement  can  be  regulated  with  nicety,  and  the  entering  air 
can  be  taken  from  the  most  desirable  point,  can  be  warmed 
or  cooled  by  a  spray  of  water,  and  filtered  in  special  chambers 
through  cocoa-nut  fibre  screens,  kept  moist  by  water,  or,  what 
is  better,  through  a  very  fine  meshwork  of  copper  wire  continu- 
ously sprayed  by  water;  and  all  this  can  be  done  at  one  spot 
for  a  number  of  rooms  or  buildings.  A  more  frequent  air  renewal 
can  be  provided  by  this  than  by  any  other  method,  and  less  dirt 
is  introduced  from  without. 

In  the  Houses  of  Parliament  at  Westminster  a  combined 
method  of  ventilation  by  propulsion  and  extraction  by  fans 
is  in  operation.  Air  is  propelled  by  rotary  fans  along  conduits 
to  the  basement,  where  it  is  filtered  through  cotton-wool  and 
warmed  in  winter  by  passing  over  steam  pipes,  and  then  passes 
upward  through  shafts  into  the  space  beneath  the  grated  floor 
of  the  House.  The  heat  can  be  regulated  by  covering  the  steam 
pipes  with  woollen  cloths,  and  in  summer  the  entering  air  can 
be  sprayed  with  water  or  cooled  by  passing  over  ice.  The 
vitiated  air  in  the  House  passes  through  a  perforated  glass  ceiling 
in  the  roof,  and  is  then  conducted  by  a  shaft  to  the  basement  of 
the  clock  tower,  where  it  passes  into  a  flue  from  which  the  air 
is  extracted  by  a  rotary  fan. 

What  is  known  as  the  "  balance  "  system — a  combination  of 


236  HYGIENE    AND    PUBLIC   HEALTH 

plenum  and  vacuum — is  specially  applicable  for  the  ventilation 
of  large  halls  and  rooms  with  extensive  seating  capacity.  In 
the  large  Examination  Hall  of  the  University  of  Cambridge  this 
system  has  been  successfully  applied.  Warm  fresh  air  is  intro- 
duced on  opposite  sides  of  the  hall,  about  7  feet  above  the  floor, 
by  means  of  a  fan,  and  is  extracted  by  another  tan  from  apertures 
in  the  ceiling  leading  to  an  extraction  shaft.  The  building  is 
warmed  prior  to  use  by  hot -water  radiators  ranged  along  the 
four  walls — it  being  far  more  economical  to  warm  a  building 
in  this  way  than  to  attempt  to  warm  it  by  the  heat  conveyed  in 
the  warmed  fresh  air  used  for  ventilation.  The  windows  of  the 
hall  are  double  glazed,  the  air  space  between  the  two  sheets  of 
glass  forming  a  non-conducting  layer,  which  not  only  prevents 
loss  of  heat  by  radiation  from  the  interior  of  the  building,  but  also 
tends  to  minimize  the  interference  with  the  proper  direction  of 
the  ventilating  currents,  which  is  caused  by  chilling  of  the  air 
in  the  neighbourhood  of  the  windows.  In  this  "  balance " 
system,  when  the  inlet  and  outlet  fans  are  properly  adjusted, 
there  is  neither  excess  nor  vacuum  pressure  within  the  building 
ventilated.  There  is,  therefore,  no  tendency,  on  the  one  hand, 
for  air  to  escape,  nor,  on  the  other,  for  air  to  enter,  except  at 
the  proper  inlets  and  outlets,  and  the  distribution  of  the  air  is 
kept  under  very  perfect  control. 

In  Verity's  system,  air  is  set  in  motion  by  a  spray  of  water 
from  a  number  of  very  fine  jets.  The  rate  of  motion  can  be  regu- 
lated by  the  tap  which  supplies  the  jet.  The  method  is  useful 
for  houses  where  it  is  not  desired  to  go  to  the  expense  of  fans 
driven  by  machinery. 

In  addition  to  hot  water  pipes,  the  incoming  air  may  be 
warmed  by  passing  it  into  firebrick  chambers,  or  through  air 
ducts,  placed  behind  and  at  the  sides  of  a  fire  grate  or  stove; 
or  the  air  may  be  warmed  by  conducting  it  through  a  tube 
which  passes  through  the  centre  of  a  gas  stove  (George's  Calorigen 
and  Bond's  Euthermic,  fig.  36). 

The  Manchester  stove  is  largely  used  for  schools,  hospitals, 
etc.  In  this  stove  the  cold  air  is  carried  along  a  shaft  placed 
between  the  joists  of  the  flooring,  and  enters  a  firebrick  chamber 
built  into  the  back  of  the  grate.  It  then  passes  through  tubes 
leading  from  the  top  of  this  chamber,  and,  travelling  round  the 
hottest  part  of  the'smoke  flue,  enters  thejroom  through  openings 
at  the  top  of  the  stove.     The  smoke  flue  is  bent  back  and  carried 


AIR    AND    VENTILATION  237 

down  the  back  of  the  stove,  passing  under  the  llooring  to  the 
outside,  where  it  is  carried  up  as  a  chimney. 

In  all  systems  of  ventilation  it  is  important  to  remember  that 
air  ducts  of  all  kinds  should  be  made  easily  accessible  for  clean- 
ing. This  principle  has  been  too  often  neglected  in  the  past, 
with  the  result  that  air  fouled  by  contact  with  dirt  is  very  fre- 
quently used  to  supply  buildings,  whilst  outlet  pipes  and  shafts 
are  found  choked  with  accumulations  and  practically  valueless. 

Ozonization  of  Air. — This  has  been  recommended  for  the 
deodorization  of  foul  atmospheres  and  for  the  destruction  of  the 
organic  matters  and  living  microbes  that  may  be  present  in  such 
air.  The  amount  of  ozone  in  the  air,  which  is  produced  by  the 
use  of  the  apparatus  of  the  Ozonair  Company,  is  ordinarily  from 
I  to  5  parts  per  million,  the  limit  for  comfortable  respiration 
being  about  lo  parts  per  million ;  above  this  amount  the  irritating 
effect  on  the  mucous  membranes  of  nose,  eye,  and  throat  begins 
to  get  very  marked.  In  the  Ozonair  Company's  apparatus,  ozone 
is  produced  by  the  action  of  an  alternating  electric  current  of 
high  frequency  on  the  oxygen  of  the  air,  through  the  medium 
of  a  non-sparking  or  silent  (condenser)  discharge,  no  oxide  com- 
pounds of  nitrogen  being  formed  by  this  form  of  discharge.  The 
machine,  when  at  work,  emits  a  continuous  stream  of  ozonized 
air,  which  for  ventilating  purposes  is  mixed  with  ordinary 
atmospheric  air,  the  resulting  mixture  having  the  composition 
above  mentioned  (i  to  5  parts  per  million  of  ozone).  The 
characteristic  smell  of  electrically  produced  ozone  is  noticeable 
in  air  containing  these  small  amounts  of  the  gas,  but  it  is  not 
disagreeable,  nor  are  there  any  irritating  effects  on  the  mucous 
membranes  of  the  eye,  nose,  or  throat,  probably  because  of  the 
absence  of  oxides  of  nitrogen. 

Air  ozonized  to  the  extent  that  is  compatible  with  comfort 
is  a  safe  and  valuable  deodorant.  Whether  volatile  organic 
matters  in  the  air  are  actually  oxidized  and  destroyed  by  these 
very  weak  dilutions  of  ozone,  or  are  merely  masked  and  rendered 
inappreciable  by  the  penetrating  odour  of  the  gas,  is  a  matter 
of  uncertainty.  What,  however,  is  certain  is  that,  in  the  very 
weak  dilutions  that  can  be  inhaled  with  safety,  ozone  has  no 
sterilizing  or  disinfectant  action  on  air-borne  micro-organisms. 
To  destroy  the  Bacillus  typhosus  in  dry  air  there  must  be  present 
0-3  per  cent,  of  ozone  in  the  air  (3,000  volumes  per  million), 
and  the  bacilli  must  be  allowed  to  remain  in  contact  with  the 


238  HYGIENE    AND    PUBLIC   HEALTH 

ozonized  air  for  one  liour,  otherwise  disinfection  is  incomplete. 
The  bacilH  of  tubercle,  influenza,  diphtheria,  and  nasal  catarrh 
are  probably  not  less,  but  more,  resistant  than  the  B.  typhosus, 
so  that  it  is  evident  that  an  atmosphere  containing  10  parts 
per  1,000,000  of  ozone — the  limit  for  respirability— has  only 
73^oth  part  of  the  amount  of  ozone  requisite  to  destroy  patho- 
genic organisms,which  must  be  left  in  contact  with  it  for  an  hour 
at  least. 

Practical  Examination  of  the  Ventilation,  of  Inhabited  Rooms. 

In  the  first  place  it  is  necessary  to  determine  the  amount  of 
cubic  space.  In  rooms  of  regular  shape  this  may  be  done  by- 
multiplying  together  the  three  dimensions  of  height,  length,  and 
breadth.  If  the  room  is  irregular  in  form,  containing  recesses 
and  projections,  or  with  a  raised  ceiling,  it  is  usually  most  con- 
venient to  divide  it  up  into  a  number  of  simpler  parts,  whose 
cubic  contents  can  be  determined  by  some  one  or  more  of  the 
following  rules : 

Area  of  circle  ==  square  of  diameter  (D-)  x  07854. 
Circumference  of  circle  =  D  x  3-1416. 

Area  of  ellipse  =  the  product  of  the  two  diameters  x  o- 7854. 
Circumference  of  ellipse  =  half  the  sum  of  the  two  diameters 

X  3-1416. 
Area  of  square  =  square  of  one  of  the  sides. 
Area  of  rectangle  =  the  product  of  two  adjacent  sides. 
Area  of  triangle  ^  basex  |  height. 
Area  of   a  parallelogram  =  divide   into  two  triangles   by  a 

diagonal,  and  take  the  sum  of  the  areas  of  the  two 

triangles. 
Area  of  trapezoid  =  half  the  sum  of  the  parallel  sides  x  the 

perpendicular   distance    between    them.      A    trapezoid 

is  a  plane  four-sided  figure  having  two  of  its  opposite 

sides  parallel. 

Area  of  segment  of  circle  =  (Ch  x  H  x  §)  -t-      _ 

2  Ch 

(Ch  =  chord,  H  =  height). 
Cubic  capacity  of  cube  or  solid  rectangle  =  length  x  height  x 

breadth. 
Cubic  capacity  of  solid  triangle  =  area  of  triangle x  1  height. 
Cubic  capacity  of  cylinder  =  area  of  base  (circle)  x  height. 


AIR   AND    VliNTILATION  .  239 

Cubic  caj)acity  of  cone  or  pyramid  =  area  of  base   (circle) 

x^-  lieight. 
Cubic  capacity  of  dome  =  area  of  base  (circle)  x  5  height. 
Cubic  capacity  of  sphere  =  D^x  0-5236. 

Thus,  supposing  it  was  required  to  determine  the  cubic  capacity 
of  a  circular  hospital  ward  jo  feet  in  diameter,  with  walls  10  feet 
high,  and  a  dome-shaped  roof  5  feet  high.  The  area  of  the  base 
or  lloor  space  is  706-86  square  feet.  The  cubic  capacity  of  the 
cylinder  below  the  dome  is  706-86x10  =  7,068-6  cubic  feet,  to 
which  must  be  added  the  cubic  capacity  of  the  dome  =  2,356-2 
cubic  feet.  So  that  the  cubic  capacity  of  the  ward  is  9,424-8 
cubic  feet. 

Having  determined  the  gross  cubic  space,  the  next  point 
is  to  determine  the  available  cubic  space,  i.e.,  the  gross  cubic 
space  less  the  space  occupied  by  solid  objects  in  the  room.  Any 
bulky  furniture  must  of  course  be  measured,  and  it  is  usual  to 
deduct  3  cubic  feet  as  the  space  occupied  by  each  individual, 
and  10  cubic  feet  for  each  bed  and  occupant.  Having  made 
these  deductions,  the  available  space  for  ventilation  is  arrived  at. 
Next,  the  various  openings  acting  as  inlets  and  outlets  respect- 
ively must  be  determined,  and  thus  the  area  of  inlet  and  outlet 
provision  per  head  can  be  ascertained.  To  distinguish  inlets 
from  outlets,  observe  the  direction  given  to  the  smoke  evolved 
from  smouldering  brown  paper  or  cotton  velvet,  when  held  close 
to  the  apertures,  some  of  which  will  be  found  to  act  as  inlets  and 
others  as  outlets.  The  rate  of  movement  of  air  through  these 
apertures  may  be  approximately  ascertained  by  placing  in  them 
an  anemometer,  which  is  an  instrument  consisting  of  four  little 
revolving  sails  driven  by  the  wind  or  current  of  air.  The  sails 
turn  an  axis  with  an  endless  screw  running  on  small  toothed 
wheels,  which,  by  means  of  a  plate  and  dial,  indicate  the  number 
of  revolutions  of  the  axis  and  the  space  traversed  by  the  sails. 
By  experiment  with  air  moving  at  a  known  rate  of  speed,  the 
anemometer  may  be  graduated.  It  appears,  however,  that  even 
tested  anemometers  are  subject  to  variations,  and  too  much 
reliance  must  not  be  placed  on  their  indications.  When  the 
instrument  is  placed  in  a  ventilating  shaft  or  opening,  it  should 
be  at  about  two-iifths  of  the  distance  from  the  centre  to  the- 
margin  of  the  opening,  that  being  the  situation  where  the  mean 
velocity  is  obtained  with  the  greatest  degree  of  approximation. 
A  modihcation  of  the  water  manometer,  or  pressure  gauge,  is 


240  ,        HYGIENE    AND    PUBLIC    HEALTH 

occasionally  used.  The  current  of  air  impinges  on  the  surfaces 
of  the  water  in  one  arm  of  a  bent  tube,  and  in  proportion  to  its 
strength  drives  the  water  up  the  other  arm,  which  is  inclined  at 
a  certain  angle.  The  records  obtained  in  this  manner  can  be 
compared  with  the  theoretical  velocities  arrived  at  by  the  use 
of  Montgolfier's  formula,  allowances  being  of  course  made  for 
friction  and  wind.  When  the  wind  is  at  all  strong  and  is 
blowing  directly  into  inlet  ventilators,  or  is  exerting  a  powerful 
aspirating  action  on  chimneys  or  exit  shafts,  calculation  is 
useless. 

As  air  enters  a  room  by  every  crack  and  crevice,  and  may  even 
do  so  through  the  brickwork  of  the  wall,  it  is  practically  impossible 
to  gauge  the  amount  of  the  incoming  air.  The  best  plan  is  to 
deduce  it  from  the  amount  which  is  leaving  the  room,  as  the  out- 
going air  will  only  leave  the  room  by  well-defined  channels  or  out- 
lets. In  an  ordinary  room  practically  the  whole  of  such  air  tends 
to  escape  by  the  fire-place,  the  entrance  to  the  flue  of  which  has 
generally  a  transverse  section  of  about  126  square  inches.  If  the 
rate  at  which  the  air  is  travelling  up  the  chimney  is  ascertained  by 
an  anemometer,  the  amount  of  air  leaving  the  room  is  easily  cal- 
culated. Thus,  assuming  the  velocity  to  be  7  feet  per  second,  then 
the  quantity  of  air  escaping  will  equal  this  velocity  x  the  sectional 

area  of  the  opening  (in  feet)  =  7X  —  =  6-i  cubic  feet  per  second, 

144 

or  21, 960  cubic  feet  per  hour.  If  samples  of  the  air  are  to  be 
taken  for  an  estimation  of  the  CO2,  any  gas  burners,  lamps,  etc., 
which  may  be  alight  at  the  time  must  be  carefully  noted,  together 
with  the  temperature  at  the  time  the  sample  is  taken. 

In  any  scheme  of  ventilation,  regard  must  be  had  to  the  follow- 
ing practical  points  : — 

1.  When  air  is  heated  it  expands  and  tends  to  rise;  when  air 
is  cooled  it  contracts  and  tends  to  fall. 

2.  Cold  air  tends  to  enter  a  room  and  to  move  about 
very  much  as  water  would;  and  this  holds  true  so  long  as  the 
temperature  of  the  fresh  air  remains  lower  than  that  in  the 
room. 

J.  The  extent  of  inlet  provision  for  fresh  air  is  not  quite  of  the 
same  importance  as  that  for  the  exit  of  foul  air;  lor  if  foul  air 
is  extracted  in  sufficient  quantities,  fresh  air  will  enter  somehow 
to  replace  it,  as  by  skirtings,  crevices  in  doors  and  windows,  or 
even  through  the  brickwork  of  the  walls. 


AIR   AND    VENTILATION  24I 

4.  The  inlet  provision  for  fresh  air  should  average  24  square 
inches  for  each  individual ;  the  provision  of  inlet  areas  somewhat 
larger  than  those  of  exit  tends  to  minimize  draughts. 

5.  Inlets  should  generally  be  as  low  in  the  room  as  possible, 
viz.,  just  above  the  floor  (so  as  not  to  raise  the  dust)  if  the  outside 
air  is  warm  or  has  been  warmed  prior  to  entry,  but  at  a  height 
of  about  5  feet  if  the  outside  air  is  cold;  otherwise  unpleasant 
draughts  are  experienced.  As  a  further  protection  against 
unpleasant  draughts  when  cold  air  is  admitted,  the  incoming 
air  should  be  directed  upwards;  while  hot  air,  since  it  tends  to 
rise,  should  be  directed  downwards. 

6.  Outlets  should  in  every  case  be  as  high  as  possible,  and 
preferably  close  to  or  in  the  ceiling;  and  they  should  have 
their  extractive  powers  maintained  by  means  of  heat  or  an 
exhaust  fan,  or  they  are  liable  to  act  as  inlets. 

7.  Where  practicable,  an  effort  should  be  made  to  so  place  out- 
lets that  the  vitiated  air  is  drawn  towards  them  before  mixing 
with  the  general  air  of  the  apartment. 

8.  There  is  a  tendency  for  fresh  air  to  take  a  direct  course 
to  the  outlets,  and  this  must  be  counterbalanced  by  a  judicious 
selection  of  the  relative  positions  of  inlets  and  outlets, 

9.  Methods  of  ventilation  devised  to  ventilate  crowded  premises 
are  generally  inefficient,  unless  the  incoming  air  can  be  warmed 
in  winter  to  about  60°  F.;  for  then  efficient  ventilation  by  cold 
air  cannot  be  tolerated,  and  there  is  a  great  tendency  among 
workers  to  close  all  ventilating  inlets. 

10.  With  less  than  250  cubic  feet  of  space  per  head,  no 
ventilation  can  be  satisfactory  which  is  not  aided  by  mechanical 
force. 

11.  The  source  of  the  incoming  air  should  be  considered.  It 
should  not  be  borrowed  from  adjoining  rooms,  but  taken  direct 
from  the  outside.  One  great  advantage  of  the  more  expensive 
mechanical  system  of  plenum  ventilation  is  the  fact  that  suffi- 
cient air  can  always  be  obtained  from  a  source  which  is  known 
and  selected. 

12.  Ventilation  dependent  on  the  extraction  of  foul  air  is  often 
more  convenient  than  that  in  which  propulsion  is  mainly  relied 
upon;  but  the  purity  of  the  air  is  not  so  easily  provided  for  or 
guaranteed. 

13.  If  warmed  air  is  forced  into  a  room,  it  should  only  be 
raised  to  a  temperature  sufficient  to  prevent  a  feeling  of  cold 

iG 


242  HYGIENE    AND    PUBLIC   HEALTH 

(about  60 ""  F.).     More  highly  heated  air  is  often  felt  to  be  overdry 
and  unpleasant. 

14.  The  heating  of  the  room  should  be  effected  by  fires,  stoves, 
or  pipes  in  the  room  itself,  and  should  not  be  made  to  depend 
upon  the  warmth  of  the  incoming  air. 

15.  It  IS  difficult  and  expensive  to  apply  methods  of  mechanical 
ventilation  to  old  premises. 


CHAPTER  IV 
WARMING  AND  LIGHTING 

Warming. 

Individual  susceptibilities  to  heat  and  cold  are  various,  depend- 
ing as  they  do  upon  age,  robustness  of  constitution,  and  previous 
habitude.  It  may,  however,  be  stated  that,  as  a  general  rule, 
the  temperature  of  a  sitting-room  or  workroom  should  be  about 
60°  F.  to  65°  F. 

Radiation. 

In  this  country  houses  are  generally  warmed  by  radiant 
heat  from  open  fire-places.  By  radiation  is  meant  the  direct 
passage  of  heat  from  warm  bodies  to  colder  ones,  the  rays  of 
heat  passing  through  the  intervening  air.  This  form  of  heat 
is  no  doubt  the  most  healthy,  for  whilst  objects  within  the 
range  of  the  fire  are  warmed,  no  impurities  are  added  to  the 
air  of  the  room.  Moreover,  the  column  of  air  in  the  chimney 
flue  is  heated,  and,  becoming  lighter,  escapes  at  the  roof  of  the 
house,  to  be  replaced  by  colder  and  denser  air  from  below,  and 
thus  an  open  fire-place  is  a  great  factor  in  ventilation.  It  is, 
however,  extremely  wasteful,  for  the  greater  part  of  the  heat 
escapes  up  the  chimney. 

The  intensity  of  radiant  heat  is  inversely  as  the  square  of  the 
distance  of  the  heated  object  from  the  source  of  heat.  Thus, 
if  there  are  two  objects,  i  foot  and  3  feet  distant  (respectively) 
from  an  open  fire-place,  the  more  distant  object  only  receives 
one-ninth  the  amount  of  heat  received  by  the  nearer  object. 
This  fact  shows  the  impossibility  of  warming  equally  all  parts 
of  a  room,  when  the  source  of  heat  is  an  open  fire-place. 

Of  late  much  has  been  done  to  improve  open  fire-places  by 
securing  the  greatest  amount  of  heating  effect  with  the  least 
consumption  of  fuel.     Some  of  these  improvements  were  made 

243 


244 


HYGIENE    AND    PUBLIC   HEALTH 


at  the  suggestion  of  the  late  Mr.  Pridgin  Teale.  They  may  be 
thus  summarized :  The  width  of  the  grate  at  the  back  should  be 
about  one-third  the  width  in  front  facing  the  room,  the  sides  of 
the  grate  being  splayed  out  at  the  necessary  angle.  The  back 
and  sides  of  the  grate  should  be  formed  of  fireclay,  and  the  back, 
instead  of  rising  perpendicularly,  should  be  "  rifle-backed,"  i.e., 
curved  forward  so  that  the  flames  may  play  upon  it  (fig.  35). 
The  curved  portion  becomes  heated  by  some  of  the  upward 
rays,  which  would  otherwise  be  lost  up  the  chimney,  and  radiates 

this  heat  into  the  room.  Vertical 
fire  bars  are  said  to  allow  more 
heat  to  radiate  into  the  room  than 
horizontal  bars. 

The  floor  of  the  grate  should 
be  formed  of  a  solid  slab  of  fire- 
clay as  in  slow  combustion 
grates;  or  if  the  lower  fire  bars 
are  retained,  a  shield  should  be 
placed  on  the  hearth,  rising  as 
high  as  the  bottom  bar  of  the 
grate,  so  as  to  form  a  hot  air 
chamber  under  the  grate  com- 
pletely cutting  off  the  air  of  the 
room  (fig.  35) ;  or  an  iron  plate 
may  be  laid  upon  the  bars  form- 
ing the  bottom  of  the  grate.  The 
object  of  this  arrangement  is  to 
prevent  a  draught  under  a  'fire 
which  hastens  combustion  and 
wastes  fuel. 

The  whole  fire-place  should  be 
brought  well  forward  into  the 
room,  the  grate  being  placed  low 
down  near  the  floor;  and  to  reduce  draught  the  chimney,  throat 
should  be  narrowed  as  much  as  possible.  A  movable  hinged 
canopy,  to  regulate  the  draught  up  the  chimney,  is  a  desirable 
arrangement. 

Open  grates  of  this  description  create  much  smoke,  as  the 
combustion  of  the  fuel  is  by  no  means  complete.  Attempts 
have  been  made  to  construct  a  smokeless  open  grate;  and  the 
plan  which  has  been  found  on  the  whole  to  answer  the  best  is 


Fig.    35. — Rifle-back    Stove 
WITH   Economizer. 

A,  hot  air  chamber;  B,  flue. 


WARMING   AND    LIGHTING  245 

to  "  underfeed  "  the  fire,  by  which  is  meant  that  the  supply 
of  fresh  fuel  is  introduced  beneath  the  incandescent  coal  which 
forms  the  top  of  the  fire,  and  through  which  the  smoke  arising 
from  thefresh  coal  must  pass,  thus  securing  complete  coml)ustion. 

In  one  of  the  best  of  these  smokeless  fire-places  a  curved  ledge 
projects  from  the  bottom  of  the  grate.  The  fresh  fuel  is  placed 
on  this  ledge  and  forced  under  the  blazing  coal  above  by  means 
of  a  special  kind  of  shovel.  These  "  underfed  "  grates  are 
found  to  be  very  efficient  heaters  for  the  amount  of  coal  con- 
sumed, and  they  continuously  expose  a  clear  fire  free  from 
smoke,  but  they  require  more  care  in  stoking  and  management 
than  ordinary  grates. 

Wherever  possible,  fire-places  and  chimney  flues  should  be 
built  in  one  of  the  inner  walls  of  a  house.  The  waste  heat  of 
the  flue  will  then  help  to  warm  the  upper  rooms.  It  is  evident 
that,  as  open  fire-places  act  as  ventilators  for  extraction  of  air, 
to  carry  on  this  function  the  column  of. air  in  the  flue  must  be 
kept  continuously  heated;  otherwise  the  chimney  will  not 
"  draw,"  and  back  currents  of  smoke  enter  the  room.  In  an 
ideal  stove,  the  heat  escaping  up  the  chimney  should  be  not 
more  than  sufficient  to  maintain  a  good  draught,  the  rest  being 
radiated  into  the  room. 

There  are  several  forms  of  "  slow  combustion  "  grates  now 
upon  the  market,  the  principle  of  which  is  to  reduce  the  draught 
through  the  fire  to  its  smallest  possible  dimensions.  One  of 
these,  the  "  Well  Fire,"  consists  of  a  fireclay  trough,  inside  which 
is  placed  a  cast-iron  grate  whereon  the  fire  rests.  The  space 
between  the  iron  and  the  fireclay  constitutes  a  hot  air  chamber 
to  which  a  continuous  current  of  air  at  a  raised  temperature  is 
admitted  by  side  tubes. 

With  a  reduction  in  the  price  of  coal  gas,  open  gas  fires  have 
come  more  largely  into  use.  As  usually  constructed,  the  flames 
from  a  row  of  Bunsen  burners  play  upon  asbestos,  in  lumps  or 
fibre,  which  is  heated  to  a  red  heat.  A  gas  fire  consumes  from 
10  to  20  or  more  cubic  feet  of  gas  per  hour.  Until  gas  is  supplied 
at  IS.  or  IS.  6d.  per  1,000  cubic  feet,  which  could  easily  be  done 
if  it  were  freed  from  illuminants,  or  until  a  public  supply  of  water 
gas  is  made  safe  and  available,  gas  fires  must  be  more  expensive 
than  coal.  But  they  have  the  advantage  of  being  very  cleanly — 
there  is  no  soot  in  the  chimney  flue  and  no  dust  or  ashes — very 
convenient,  and  of  causing  no  trouble.  As  regards  the  prevention 


246  HYGIENE    AND    PUBLIC    HEALTH 

of  smoke,  the  more  extended  use  in  our  large  towns  of  coal  gas 
for  heating  and  cooking  would  undoubtedly  tend  to  free  the  air 
from  much  of  the  soot  and  smoke  that  now  pollute  it.  Fogs, 
which  depend  so  largelj'  upon  climate  and  site,  would  be  just 
as  frequent,  though  less  sooty  and  yellow.  They  would  also  be 
less  sulphurous,  for  the  sulphur  compounds  produced  by  gas 
combustion  are  less  than  those  produced  by  coal. 

It  is  probable  that  wmter  gas  would  come  largely  into  use  for 
heating  and  illuminating  purposes — for  gas  fires  and  gas  cooking 
stoves,  and  for  incandescent  burners — were  it  not  dangerous, 
from  containing  such  a  large  percentage  of  carbonic  oxide. 
Water  gas  is  produced  by  blowing  steam  through  incandescent 
coke  or  other  carbonaceous  matter,  raised  to  a  high  temperature 
in  a  "  generator  "  furnace  by  the  aid  of  an  air  blast.  The  in- 
candescent coke  gives  off  what  is  known  as  "  producer  gas," 
and  this  is  led  away  from  the  generator  before  the  steam  is 
introduced.  The  introduction  of  the  steam  is  only  continued 
for  about  four  minutes,  after  which  time  it  is  necessary  to  turn 
on  the  air  blast  again  to  reheat  the  coke.  The  "  producer  gas," 
consisting  largely  of  carbonic  oxide,  is  used  for  heating  the 
boilers  which  generate  the  steam.  It  will  thus  be  seen  that  the 
process  consists  of  alternately  blowing  the  generator  hot  (for 
ten  minutes),  when  producer  gas  is  formed  and  led  away,  and 
of  making  water  gas  by  introducing  steam  over  the  hot  fuel 
(for  four  minutes) .  In  this  way  the  water  is  split  up  into  hydro- 
gen and  oxygen;  the  hydrogen  remains  free,  and  the  oxygen 
with  most  of  the  carbon  forms  carbon  monoxide,  the  mixture 
being  "  water  gas."  The  water  gas,  as  formed,  is  passed  over 
scrubbers  and  purified  over  oxide  of  iron,  in  much  the  same  way 
as  coal  gas,  before  being  stored  in  gas  holders;  it  then  consists 
of  hydrogen  gas  (about  35  per  cent.)  and  of  carbonic  oxide  (25 
to  35  per  cent.),  marsh  gas  20  per  cent.,  and  10  per  cent,  of 
ethylene,  etc.  In  heating  power  water  gas  is  far  superior  to 
coal  gas;  and  as  the  only  products  of  combustion  are  H2O 
vapour  and.C02,  the  sulphur  products  of  combustion  of  coal 
gas  are  avoided.  Water  gas,  too,  can  be  produced  very  cheaply, 
viz.,  at  about  4^/.  per  1,000  cubic  feet.  But  the  large  quantity 
of  CO  in  water  gas  causes  it  to  act  as  a  powerful  poison,  and 
yet,  from  being  odourless,  escapes,  if  they  occur,  are  not  at  once 
detected.  For  lighting  purjioscs  the  gas  is  "  carburetted  " — 
that  is,  enriched  by  hydrocarbons  derived  fnjm  oil.     This  car- 


WARMING   AND    LIGHTING  247 

buretted  water  gas  smells  much  like  coal  gas;  its  candle  power 
is  greater,  and  it  is,  on  the  whole,  cheaper  to  make.  It  has 
been  adopted  lor  lighting  purposes  in  many  towns  in  America, 
and  it  is  often  used^  mixed  with  coal  gas,  in  this  country.  A 
recent  Departmental  Committee  recommended  a  statutory  limit 
of  12  per  cent,  of  CO  in  any  illuminating  gas;  for  an  escape 
leading  to  the  presence  of  0-4  per  cent,  of  CO  in  the  general 
atmosphere  may  prove  fatal. 

It  is  perhaps  needless  to  point  out  that  plumbers  should 
never  be  allowed  to  fix  a  gas  fire,  or,  in  fact,  any  gas  consuming 
appliance  (such  as  a  bath  heater  or  "  geyser  "),  which  burns 
more  than  12  feet  of  gas  per  hour,  without  providing  a  chimney 
flue  to  carry  off  the  products  of  combustion  to  the  outer  air. 

Ventilating  grates  may  be  combined  with  open  fire-places. 
The  usual  method  is  to  construct  a  chamber  lined  with  fireclay 
at  the  back  and  sides  of  the  fire-place,  and  extending  up  around 
the  lower  part  of  the  chimney  flue.  An  opening  below  admits 
fresh  air  from  outside  the  house  into  the  chamber,  where  it  is 
warmed  and  escapes  by  an  opening  into  the  room  above  the 
chimney-piece.  Galton's  Grate  and  the  Manchester  School 
Grate  act  upon  this  principle. 

Conduction  and  Convection. 

By  conduction  heat  passes  from  one  molecule  of  air  to  another 
in  contact  with  it;  but,  as  air  is  a  very  bad  conductor  of  heat, 
the  process  is  very  slow.  The  conveyance  of  heat  by  means  of 
the  movements  of  masses  of  heated  air  (convection)  is  the  most 
effectual  agent  for  heating.  Air  when  heated  expands  and 
becomes  lighter  bulk  for  bulk  than  colder  air,  so  it  rises  upwards, 
its  place  being  taken  by  the  colder,  denser  air. 

Houses  may  be  heated  by  means  of  stoves  in  which  coal, 
coke,  gas,  or  oil  is  burnt,  by  hot  water  and  steam  pipes,  or  by 
"  radiators,  "  which  are  radiators  only  in  name,  their  heating 
effect  being  due  to  convection.  The  air  coming  in  contact  with 
the  heated  surfaces  is  warmed,  and  therefore  expands  and  rises, 
and  is  replaced  by  colder  air.  In  this  way  currents  of  air  are 
maintained  which  circvilating  about  a  room  tend  to  heat  every 
part  of  it.  The  most  satisfactory  way  of  uniformly  heating  the 
whole  house  is  by  warming  the  air  of  the  entrance  hall  by  means 
of  hot  water  pipes,  a  hot  water  radiator  connected  with  the 
kitchen  boiler,  or  a  ventilating  stove  placed  in  the  hall.    The 


hs 


HYGIENE  AND  PUBLIC  HEALTH 


warm  air  which  ascends  can  then  be  admitted  to  all  the  rooms 
above  the  ground  floor  by  openings  o^•er  the  doors,  which  openings 
may  be  fitted  with  valves. 

The  great  distinction  between  stoves  and  open  fire-places  is 
that,  whilst  in  the  latter  the  heated  air  escapes  up  the  chimney, 
in  the  former  the  heated  air  circulates  through  the  room. 

There  is  a  great  variety  of  heating  stoves,  but  they  may  all  be 
classified  as  either  dose  or  ventilating  stoves.  In  the  former  kind 
no  arrangement  exists  for  providing  fresh  warmed  air;  whilst  in 
the  latter  fresh  air  from  outside  the  house  is  made  to  circulate 

through  the  stove,  with- 
out coming  into  contact 
with  the  products  of  com- 
bustion, and  is,  when 
warmed,  allowed  to  enter 
the  room.  Bond's  Eu- 
thermic  Stove  is  one  of 
the  best  forms  of  venti- 
lating stove.  In  this  the 
fresh  air  from  the  out- 
side is  conveyed  to  and 
warmed  in  a  central  up- 
right tube,  which  com- 
municates with  the  room 
at  the  top  of  the  stove. 
The  space  between  this 
tube  and  the  outer  case 
of  the  stove  is  open 
below,  where  a  circle  of 
gas  jets  burn,  and  above 
it   communicates  with   a 


/K 


A 


\  J 


Fig.  5(). — Euthermic  Ventilating  Gas 
Stove. 

A,  fresh  air  chamber;    B,  ring  of  Bunsen 
gas  burners;  C,  to  foul  air  flue. 


flue.  Thus,  not  only  is  warmed  fresh  air  supplied  to  the  room, 
but  also  foul  air  is  removed  along  with  the  products  of  combustion 
between  the  inner  tube  and  the  outer  case. 

From  an  inquiry  undertaken  by  the  Lancet  into  the  general 
efficiency  of  gas  stoves,  the  following  facts  emerged :  A  properly 
constructed  gas  stove  with  a  suitable  flue,  while  more  costly 
than  a  coal  fire,  does  not  vitiate  the  air  of  a  room  nor  produce 
any  abnormal  drying  effect  upon  it ;  more  heat  is  lost  in  the  flue 
gases  in  coal  fires  than  in  gas  fires ;  coal  fires  take  longer  to  warm 
a  room  than  gas  fires  ;  as  gas  fires  arc  so  easily  regulated,  the 


WARMING   AND    LIGHTING  249 

temperature  of  a  room  can  be  controlled  in  a  manner  whicli 
is  not  possible  with  coal  fires,  and  a  more  e{[uable  temj^erature  is 
maintained  with  a  gas  tire  with  an  absence  of  dust  and  smoke; 
no  carbon  monoxide  was  detected  in  the  hot  air  and  gases  coming 
from  these  stoves,  except  in  one  instance  where  the  stove  was 
faulty. 

In  all  stoves  economy  of  fuel  is  aimed  at,  by  providing  doors 
and  dampers  to  shut  off  the  draught  and  make  the  comlnistion  as 
slow  as  possible;  and  the  flues  are  sometimes  carried  horizontally 
for  some  distance,  in  order  that  extra  heat  may  be  obtained. 
It  is  evident  that  the  slower  the  combustion  and  the  more 
complete  the  utilization  of  the  heat  of  the  burning  fuel  in  warm- 
ing the  room,  the  less  does  a  close  stove  act  as  an  exliaust  ven- 
tilator; and  economy  of  fuel  and  utilization  of  heat  may  be 
procured  at  the  expense  of  healthiness. 

The  ventilating  stoves  which  introduce  a  supply  of  fresh 
warmed  air  are  decidedly  more  healthy;  but  there  are  certain 
disadvantages  which  require  consideration  in  the  use  of  stoves 
of  all  kinds. 

In  the  first  place,  they  are  apt  to  render  the  air  oi  a  room  too 
drj^  and  therefore  unpleasant  to  the  nose,  eyes,  and  skin.  There 
may  be  the  same  amount  of  moisture  in  a  cubic  foot  of  heated 
air  as  in  a  similar  bulk  of  cold  air  before  it  is  warmed;  but  the 
relative  humidity  of  the  air  when  heated  would  be  greatly 
diminished,  as  hot  air  is  capable  of  holding  more  moisture,  before 
saturation  is  reached,  than  cold  air;  and  it  is  upon  relative 
humidity  to  some  extent  that  health  and  comfort  depend.  This 
drawback  may,  to  a  certain  extent,  be  overcome  by  placing 
vessels  of  water  in  the  room  or  on  the  stove. 

Secondly,  if  the  stove  becomes  overheated,  the  organic  matters 
in  the  air  become  charred  by  contact  with  the  heated  surface. 
and  a  disagreeable  close  smell  is  perceived. 

Lastly,  the  presence  of  carbonic  oxide  has  been  detected  in 
the  air  of  stove-heated  rooms  when  the  stove  is  of  cast  iron. 
Either  this  gas  passes  out  of  the  furnace  through  invisible 
fissures  in  the  cast  iron,  or  it  traverses  the  walls  of  the  stove 
when  at  a  red  heat.  Others  suppose  that  the  gas  may  be  formed 
by  incomplete  combustion  of  particles  of  carbon  or  organic 
matter  floating  in  the  air,  when  brought  into  contact  with  the 
hot  metal. 

Cast-iron  stoves  are  very  liable   to   become  overheated,   as. 


250  HYGIENE    AND    PUBLIC   HEALTH 

being  good  conductors,  they  rapidly  heat  and  cool.  In  such 
stoves,  therefore,  the  heating  surface  should  be  increased  by 
vertical  flanges  projecting  from  the  top  and  sides,  by  which 
means  the  heat,  being  conveyed  to  a  larger  surface,  is  less  in- 
tense, because  cooHng  is  more  rapid.  It  is  safer  not  to  use 
cast-iron  stoves  at  all,  unless  lined  inside  with  fireclay;  this, 
being  a  good  non-conductor,  prevents  the  over  rapid  heating 
of  the  iron  walls,  and  the  warming  of  the  room  is  altogether 
more  equable.  There  are  many  ornamental  stoves  now  made 
entirely  of  fireclay  and  china,  with  arrangements  for  the  supply 
of  warmed  fresh  air  at  an  agreeable  temperature  of  about  65° 
to  70°  F.  They  are  especially  valuable  for  heating  halls  and 
public  buildings. 

No  ill  effects  appear  to  follow  upon  the  use  of  oil  stoves  in 
living  rooms,  if  the  combustion  of  the  oil  is  complete  and  there 
is  efficient  air  renewal  in  the  room,  despite  the  general  absence 
of  flues  to  convey  away  the  products  of  combustion. 

Steam  pipes  are  largely  used  for  heating  factories  and  work- 
shops and  public  buildings  where  steam  power  and  waste  steam 
are  at  hand. 

Systems  of  Healing  by  Hot  Water  or  Steam. 

The  impossibility  of  adequately  warming  large  rooms, 
halls,  theatres,  and  other  public  buildings  by  open  fire-places 
or  stoves  has  led  to  the  adoption  of  various  systems  of  hot 
water  or  steam  heating,  of  which  the  principal  varieties  in 
use  are: 

High  Pressure  Gravity  Hot  Water. — The  pipes  are  of  welded 
wrought  iron  of  small  diameter  (^  inch  internal  diameter). 
There  is  no  boiler,  the  water  being  heated  by  a  coil  of  the  piping, 
of  about  one-sixth  the  total  length,  passing  through  a  brick 
furnace.  An  expansion  tank  is  connected  to  the  highest  point 
of  the  system,  in  which  is  fixed  a  combined  "  blow  off  "  and 
"  suction  "  valve.  As  the  water  expands  on  heating,  the  valve 
lifts  off  its  seat,  and  the  surplus  water  escapes  into  the  expansion 
tank,  until  the  proper  working  pressure  is  reached.  When  the 
furnace  is  drawn  or  not  replenished,  the  water  in  the  pipes  cools, 
contracts,  and  creates  a  vacuum.  The  suction  valve  then  comes 
into  action,  and  water  passes  from  the  tank  into  the  pipes.  The 
water,  being  under  pressure,  can  be  heated  to  300°  or  350°  F.; 
but  although  this  renders  the  system  eflicient  as  a  heat  producer, 


WARMING    AND    LIGHTING 


251 


the  high  temperature  of  the  healing  surface  causes  an  unpleasant, 
stuffy  atmosphere — probably  from  charring  of  organic  matter  in 
the  air.  Such  atmospheres  are  often  productive  of  headache, 
lassitude,  and  dry  sensations  in  the  throat,  the  latter  being  due 
to  ovcrdrying  of  the  air  (low  relative  humidity). 

lypes    O^  [^QdioVors   wife  Tvestg.  gir  IrzJgts 


OcQY-  Spoce  onder  <j>r  c\iian\<zij 


Words 

Fig.  37. 


Low  Pressure  Gravity  Hot  Water — (i)  Healing  by  Hot  Water 
Pipes. — In  this  system  2  or  3  inch  cast-iron  pipes  are  connected 
with  a  boiler  at  the  base  of  the  system,  so  as  to  provide  a  com- 
plete circulation.  The  water  is  heated  in  the  boiler,  circulates 
through  the  pipes,  parting  with  some  of  its  heat  to  the  air  in 
contact  with  them,  and  on  cooling  returns  to  the  boiler,  the 
circulation   being   due   to   the   difference   between   the   specific 


252  HYGIENE    AND    PUBLIC    HEALTH 

gravities  of  the  water  in  the  flow  and  return  pipes.  An  expan- 
sion tank  is  connected  to  the  highest  point  of  the  system  to 
allow  for  increase  in  volume  of  the  water  when  heated,  and  the 
tank  is  supplied  with  water  from  the  house  supply  by  a  ball 
valve.  At  the  highest  point  of  the  system,  or  at  any  place 
where  air  is  likely  to  collect,  a  small  air  escape  pipe  should  be 
carried  to  the  outer  air. 

(2)  Heating  by  Radiators. — In  this  system  the  circulating  pipes 
are  of  small  diameter  (about  an  inch  or  less),  and  the  heating 
effect  is  produced  by  radiators  fixed  at  convenient  points,  the 
radiators  being  vertical  pipe  coils  of  ornamental  pattern.  Each 
radiator  is  controlled  by  a  valve  to  entirely  or  partially  cut  off 
the  flow  of  water  through  it,  and  thus  the  temperature  can  be 
regulated  to  some  degree  of  nicety.  An  air-cock  is  also  provided 
to  allow  air  to  escape  when  the  radiator  is  filling. 

The  great  advantage  of  these  two  systems  is  that  the  heating 
surfaces  are  maintained  at  a  comparatively  low  temperature, 
seldom  rising  above  180°  F.,  and  there  is,  in  consequence,  very 
much  less  tendency  for  the  air  to  become  stuffy  from  over- 
heating and  overdrying.  The  system  is  simple,  is  inexpensive  to 
install  and  maintain,  and  the  boiler  only  requires  stoking  at  long 
intervals.  On  the  other  hand,  in  buildings  of  irregular  shape 
and  height  there  may  be  some  difficulty  in  maintaining  a  regular 
and  even  flow  of  water  through  all  parts  of  the  system,  and  air- 
locks often  given  rise  to  trouble. 

Low  Pressure  Hot  Water,  ivith  Assisted  Circulation. — To  over- 
come the  difficulties  arising  from  irregular  flow,  when  the  force 
of  gravity  alone  is  depended  upon,  the  use  of  steam  to  assist  the 
flow  has  been  successfully  applied.  In  Barker's  "  cable  "  system, 
steam  is  led  from  a  boiler  into  an  apparatus  consisting  of  two 
chambers  side  by  side.  In  the  first  chamber,  the  water  to  be 
heated  comes  in  contact  with  the  live  steam  by  falling  in  drops 
through  a  perforated  tray.  On  reaching  a  certain  height  in  the 
chamber,  the  heated  water  opens  a  valve,  and  passes  into  the 
second  chamber.  When  this  chamber  is  full,  a  valve  is  opened 
which  admits  steam,  and  the  heated  water  is  forced  by  steam 
pressure  into  an  expansion  tank  above  the  apparatus,  from 
whence  it  passes  into  the  main  flow  pipe  leading  to  the  radiators, 
and  thence  by  a  return  main  to  the  first  chamber.  In  this 
chamber  the  condensation  of  the  steam,  as  it  heats  the  incoming 
water,  causes  a  partial  vacuum,  which  very  materially  aids  the 


WARMING    AND    LIGHTING  253 

return  flow  of  water.  The  whole  work  of  the  apparatus  is  auto- 
matic, and  requires  no  attention.  It  will  be  seen  that  the  hot 
water  is  forced  to  travel  through  the  system  by  steam  pressure 
and  gravity,  and  is  aided  in  its  return  by  the  suction  induced  by 
steam  condensation.  It  is  due  to  this  that  very  small  pipes  only 
are  required  for  the  mains  and  branches,  and  considerable 
obstacles  in  the  way  of  dips  can  be  overcome,  as  the  motive 
forces  render  the  system  very  largely  independent  of  friction. 
The  temperature  of  the  circulating  water  can  be  regulated  to 
anything  between  ioo°  F.  and  200°  F.,  the  temperature  usually 
employed  being  150°  F.  or  160°  F.,  so  as  not  to  overheat  or 
overdry  the  air. 

The  invention  of  the  "  assisted  "  hot  water  circulation  has 
enabled  a  novel  method  of  heating  to  be  introduced,  which  would 
not  have  been  possible  without  it.  In  this  system  the  pipes, 
which  need  be  only  of  small  diameter — less  than  i  inch — are 
laid  in  a  composition  material  similar  to  those  now  in  use  for 
floors,  and  consisting  for  the  most  part  of  compressed  sawdust, 
cement,  and  asbestos.  This  material,  with  its  contained  hot 
water  pipes,  is  laid  as  panels  in  the  floor  or  walls  of  a  room,  and 
the  room  is  heated  by  its  warm  floor  or  walls.  The  surface 
temperature  of  the  panel  is  a  low  one,  so  that  there  is  no  risk  of 
overdrying  or  of  overheating  the  air  ;  and  the  source  of  heat  being 
low  down,  near  or  at  the  floor  level,  the  feet  of  the  occupants 
are  kept  warm,  and  cold  currents  of  air  near  the  floor  level, 
causing  "  cold  feet,"  are  avoided.  A  very  comfortable  equable 
temperature  is  obtained  by  the  "  panel  "  system  of  heating,  and 
there  are  no  unsightly  pipes,  radiators,  or  other  fittings  to  de- 
tract from  the  architectural  or  decorative  amenities  of  the 
apartment. 

There  are  various  systems  of  Loiv  and  High  Pressure  Steam 
Heating,  but  the  most  useful  is  the  Vacuum  System,  as  in  this  the 
temperature  of  the  steam  does  not  rise  above  212°  F.  Steam 
is  led  from  a  boiler  to  the  radiators,  which  are  similar  to  those 
on  hot-water  systems.  The  steam,  however,  is  reduced  to  atmo- 
spheric pressure  by  a  reducing  valve  alter  leaving  the  boilers, 
and  is  condensed  in  the  radiators,  the  condensed  water  passing 
through  the  exhaust  pipe  to  a  vacuum  chamber  worked  by  a 
vacuum  pump,  where  a  vacuum  of  10  or  12  pounds  is  main- 
tained. The  radiators  are  fitted  with  valves  to  shut  off  the 
steam  when  required.     The  steam  system  of  heating  overcomes 


254  HYGIENE  AND  PUBLIC  HEALTH 

all  the  difficulties  connected  with  the  distribution  of  heat  in 
large  and  irregular  shaped  buildings,  and  very  uniform  tem- 
peratures can  be  attained  in  all  parts  of  such  buildings.  On 
the  other  hand,  the  heating  surfaces  are  usually  over  a  tem- 
perature of  200°  F.,  and  there  is  more  tendency  to  the  creation 
of  overheated  and  stuffy  atmospheres  than  with  low  pressure 
hot  water  systems. 

Stuffy  Atmospheres. — The  exact  cause  of  the  stuffiness  of 
atmosphere  created  when  air  is  heated  by  contact  with  surfaces 
of  over  200°  F.  has  not  been  determined.  It  is  not  altogether 
a  question  of  relative  humidity,  as  the  air  of  rooms  warmed  by 
radiant  heat  from  open  fire-places  is  often  found  to  be  of  low 
relative  humidity  (less  than  50),  whilst  it  is  fairly  fresh  to  the 
sense  of  smell,  and  has  no  stuffy  characteristic.  The  sensation 
of  freshness,  however,  would  appear  to  be  due  to  three  more  or 
less  co-existing  conditions — ^namely,  (i)  absence  of  any  odour 
due  to  organic  matters  or  charred  organic  matters;  (2)  an  air 
temperature  not  exceeding  65°  F.,  when  the  external  tempera- 
ture is  below  the  internal  (room);  and  (3)  slow  movements  of 
masses  of  air  at  slightly  unequal  temperatures,  i.e.,  non-stagna- 
tion. 

Recent  physiological  research  is  inclined  to  place  especial 
emphasis  on  movements  of  masses  of  air  at  somewhat  different 
temperatures  as  being  essential  to  the  continuous  stimulation 
of  the  surface  cutaneous  nerves  of  the  body,  on  which  health 
and  comfort  so  largely  depend.  The  warm  stagnant  atmosphere 
is  relaxing  and  depressing,  whilst  the  atmosphere  displaying 
continuous  gentle  movements,  owing  to  slightly  varying  tem- 
peratures in  different  parts  or  at  different  levels,  is  both  stimulat- 
ing, refreshing,  and  healthful.  In  the  latter  case,  the  cutaneous 
stimulation  assists  the  circulation  of  the  blood  in  the  cutaneous 
vessels;  in  the  former,  the  absence  of  any  stimulation,  combined 
with  excessive  heat,  leads  to  cutaneous  vascular  stagnation  and 
retention  of  waste  products  in  the  blood,  the  latter  being  the 
cause  of  the  lassitude  and  depression  experienced  by  the  occu- 
pants. 

The  continued  breathing  day  after  day  of  "  stuffy  atmos- 
pheres "  is  apt  to  produce  headache,  inability  to  concentrate 
the  attention,  drowsiness,  lassitude,  depression  of  spirits,  loss  of 
appetite,  dr3mess,  of  the  throat  and  nose,  with  consequent  thirst, 
a  tendency  to  ""  take  cold  "  easily,  and  in  some  cases  actual 


WARMING    AND    LIGHTING  255 

fever  has  been  produced,  or  a  diminished  resistance  to  the  onset 
of  influenza  and  otlicr  infectious  diseases. 

It  must  not  be  supposed,  however,  that  it  is  healthful  to  be  in 
a  room  with  a  "  thorough  draught."  In  such  a  case,  either  the 
movement  of  air  is  too  great,  or  the  temperature  of  the  moving 
air  is  too  far  removed  from  that  of  the  bulk  of  the  atmosphere 
in  which  the  person  is  sitting.  The  effect  of  a  "  thorough 
draught  "  is  to  cause  too  much  stimulation  of  the  cutaneous 
circulation,  with  the  result  that  the  cutaneous  vessels  contract 
and  drive  the  blood  to  the  internal  organs,  leaving  the  skin  cold, 
whilst  the  internal  organs  are  unduly  congested.  Chills  are  thus 
induced,  which  may  have  serious  results  and  be  the  precursors 
of  illness.  The  chill  certainly  seems  to  render  the  body  less 
resistant  to  the  invasion  of  pathogenic  micro-organisms,  which 
may  be  present  at  any  time  in  the  mucous  membranes  of  the 
upper  air  passages.  Many  people  prove  resistant  to  chill  if 
the  body  faces  a  cold  current  of  air,  who  succumb  if  the  back 
and  loins  are  unduly  cooled. 

Radiators. — The  low  pressure  steam  is  specially  suitable  in 
high  buildings,  and  where  the  apparatus  is  not  in  use  the  fact 
that  the  pipes  are  empty  removes  the  risk  of  damage  by  frost. 
Wherever  the  low  pressure  hot  water  system  is  installed,  radia- 
tors should  be  located  under  the  windows,  as  these  are  the 
points  at  which  the  greatest  loss  of  heat  occurs.  It  is  a  good 
practice  to  construct  radiators  without  feet,  but  carried  on  cast- 
iron  brackets  built  into  the  wall ;  this  facilitates  cleaning. 

Ventilating  heat  radiators  are  now  largely  used.  They  are 
fixed  against  an  outer  wall,  so  that  fresh  air  can  be  conducted 
into  the  base  of  the  radiator,  and  thence  pass  over  the  heating 
surface  to  escape  into  the  room  through  a  grating  at  the  top  of 
the  radiator.  By  means  of  a  valve,  the  communication  with 
the  outer  air  can  be  closed  if  desired.  The  ventilating  effect, 
however,  is  slight,  for  the  amount  of  fresh  air  capable  of  intro- 
duction in  this  way  is  small,  unless  there  is  some  extractive  force 
available  to  remove  air  from  the  radiator-heated  room.  Some 
form  of  hopper  window  ventilator  is  generally  necessary  in  a 
radiator-heated  room^  which  will  allow  the  entry  of  compara- 
tively large  volumes  of  fresh  air  at  the  lower  part  of  the  window 
directly  above  the  radiator.  The  cold  fresh  air  entering  from 
the  window  then  mixes  with  the  warm  air  ascending  from  the 
radiator. 


256  HYGIENE   AND    PUBLIC   HEALTH 

Electric  radiators  possess  the  advantages  of  yielding  no  pro- 
ducts of  combustion,  and  the  heat  is  available  immediately  the 
current  is  turned  on,  but  the  cost  of  heating  by  this  method  is 
high  at  ordinary  rates  for  current. 

The  fixing  of  the  source  of  heat  near  the  ceiling  instead  of 
near  the  floor  has  recently  been  advocated.  The  circulating 
fluid  (steam  or  hot  water)  is  carried  in  flow  and  return  pipes 
around  one  or  more  sides  of  the  room,  about  i  foot  below  the 
ceiling.  The  advantage  claimed  is  that,  on  the  side  of  the  room 
adjoining  windows,  these  can  be  opened  at  the  top,  and  the 
fresh  air  passing  in  over  the  pipes  is  warmed  sufficiently  to  obviate 
all  draughts,  whilst  circulating  currents  of  air  at  slightly  dif- 
ferent temperatures  are  set  up  in  the  room,  which  prevent  stagna- 
tion of  atmosphere,  and  cause  the  healthful  feeling  of  "  moving 
air  "  currents. 

Soft  water  is  far  preferable  to  hard  water  for  use  in  boilers 
and  hot  water  pipes.  The  deposit  of  lime  salts  from  hard  water 
gradually  narrows  the  calibre  of  the  pipes,  which  in  time  may 
become  completely  blocked.  In  boilers,  the  deposit  forms  a 
non-conducting  lining,  which  obstructs  the  passage  of  heat  to  the 
water.  When  the  fur  lining  is  thick  it  may  lead  to  an  explosion, 
for  the  iron  boiler  plates  become  red  hot  from  the  heat  of  the 
fire.  Should  a  crack  in  the  fur  suddenly  form,  the  water,  coming 
in  contact  with  the  red  hot  metal,  is  converted  into  steam  with 
explosive  violence.  Another  cause  of  explosion  in  kitchen 
boilers  which  are  not  connected  with  a  hot  water  cistern,  or  are 
unprovided  with  a  steam  escape  pipe,  is  the  blocking  of  the 
pipe  which  supplies  cold  water  to  the  boiler.  This  occasionally 
happens  after  a  hard  frost,  if  the  pipe  is  unprotected. 

In  adopting  a  scheme  for  heating  purposes  it  is  necessary  to 
consider  the  heat  required  to  raise  and  maintain  the  temperature 
of  the  air,  and  in  addition  to  this  the  further  quantity  necessary 
to  replace  the  heat  lost  through  windows,  etc. 

Lighting. 

The  illumination  of  a  room  is  a  matter  greatly  affecting  the 
comfort  and,  indirectly,  the  health  ot  the  occupants,  and  is  of 
especial  importance  to  eyesight  in  the  case  of  factories,  work- 
shops and  schools,  where  the  eyes  are  concentrated  on  small 
objects  tor  many  hours  at  a  time. 


WARMING   AND    LIGHTING  257 

A rtificial  Lighting. 

The  most  commonly  employed  in'i^+hod  of  obtaining  an  artificial 
illumination  is  the  combustion  of  inilammable  material  pro- 
ducing a  Hame.  Coal  gas,  petroleum  and  colza  oils,  and  candles, 
are  well  known  examples  of  this  form  of  illumination.  In  the 
electric  light,  on  the  other  hand,  there  is  no  combustion,  or 
only  to  a  trifling  extent ;  but  light  is  emitted  from  a  substance 
raised  to  a  high  temperature  and  a  state  of  incandescence  by  the 
passage  through  it  of  an  electric  current. 

The  inflammable  gases  and  vapours  are  chiefly  compounds 
of  carbon  and  hydrogen.  When  these  inflammable  vapours  are 
heated  to  a  suihcient  temperature,  the  hydrogen  combines  with 
oxygen  to  form  water  vapour,  and  an  intensely  hot  flame  with- 
out luminosity  is  produced;  the  carbon  particles,  which  are 
liberated  in  a  state  of  very  tine  subdivision,  are  rendered  incan- 
descent by  the  heat  of  the  hydrogen  flame,  and  they  combine 
with  oxygen  to  form  CO2  and  traces  of  CO.  The  luminosity, 
which  is  situated  in  the  outer  portion  of  the  flame,  is  due  to 
the  incandescent  carbon,  whilst  the  inner  portion — the  hydrogen 
flame — is  very  hot,  but  almost  non-luminous.  The  products 
of  combustion  are  chiefly  water  vapour  and  carbonic  acid. 
The  light  is  very  deficient  in  the  blue  and  violet  rays  of  the 
solar  spectrum,  and  has  therefore  a  yellow  or  orange  colour. 
Hence  the  true  colours  of  objects  illuminated  by  a  flame  are 
not  perceptible. 

Coal  Gas. — The  principal  illuminant  of  coal  gas  is  heavy 
carburetted  hydrogen  or  olefiant  gas  (C2H4).  There  are  also 
present  other  hydro-carbons — i.e.,  benzene,  propylene,  naphtha- 
lene— which  are  illuminants.  The  heavy  hydro-carbons,  if 
burned  by  themselves,  would  yield  a  smoky  flame ;  but  these  are 
suitably  diluted  in  coal  gas  by  hydrogen,  marsh  gas  or  methane, 
and  carbonic  oxide,  which  together  form  over  90  per  cent,  of 
the  coal  gas. 

Coal  gas  illumination  was  a  great  advance  on  the  candle 
iUumination  of  a  former  period,  but  it  has  certain  drawbacks. 
There  is  the  danger  of  escape  of  gas  in  the  houses  from  mains 
and  pipes,  forming,  if  the  escape  is  large,  explosive  mixtures 
with  the  oxygen  of  the  air;  or  if  small,  causing  a  serious  pollu- 
tion of  the  atmosphere.  The  products  of  combustion  are 
injurious  to  health,  and  the  sulphurous  acid  from  the  sulphur 

17 


258  HYGIENE    AND    PUBLIC   HEALTH 

compounds  in  coal  gas  is  destructive  to  books,  furniture,  and 
pictures.  The  combustion  also  heats  the  air  and  dries  it;  lor 
although  watery  vapour  is  one  of  the  products,  the  relative 
humidity  of  the  air  at  the  higher  temperature  is  lowered. 
Finally,  when  the  supply  of  gas  and  air  is  not  regulated  during 
combustion,  the  gas  is  wasted,  the  light  is  lessened,  and  un- 
consumed  particles  of  carbon  are  given  off  which  deposit  as 
soot  on  adjacent  cold  surfaces. 

The  burners  in  common  use  are:  (i)  The  fish  tail  or  union 
jet,  which  has  a  flat  steatite  top,  slightly  depressed  in  the  centre, 
through  which  two  small  holes  are  bored  in  directions  inclining 
towards  one  another  from  below  upwards.  The  two  streams 
of  gas  meet  and  produce  the  flat  flame  usually  seen.  (2)  The 
bitwing  has  a  hemispherical  steatite  top,  through  which  a  vertical 
slit  is  cut  lor  the  gas  to  issue.  The  flame  is  flat  and  semicir- 
cular. The  flames  from  these  two  burners  require  no  chimneys, 
but  are  usually  enclosed  in  globes  to  soften  the  light.  (3)  The 
Argand  burner  is  a  small  ring  or  double- walled  cylinder,  pierced 
at  the  top  with  fine  holes  for  the  issue  of  the  gas.  The  flame 
thus  forms  a  hollow  cylinder,  and  the  air  has  free  access  both 
to  its  interior  and  exterior.  The  flame  must  be  enclosed  in  a 
chimney,  in  order  that  the  supply  of  air  to  it  may  be  regulated. 

The  Argand  burner  has  been  improved  by  Silber,  Sugg,  and 
other  manufacturers.  These  improvements  are  directed,  first, 
to  cause  the  issue  of  the  gas  at  the  lowest  possible  velocity, 
and,  secondly,  to  divide  and  regulate  the  air  supply  both  to 
the  outside  and  inside  of  the  flame,  and  to  direct  a  part  of  it  to 
the  higher  portions  of  the  flame,  where  perfect  oxidation  of  the 
carbon  is  most  required.  These  improved  Argands  give  a  far 
better  and  steadier  light  for  the  same  consumption  of  gas  than 
the  flat  flame  burners. 

There  are  several  ventilating  burners  in  which  the  products  of 
combustion  ol  the  flame  are  conducted  through  a  flue  to  the 
external  air,  the  heated  and  vitiated  air  from  the  top  of  the 
room  or  hall  being  also  removed  by  ducts  surrounding  the  flue. 
The  sunlight  burners  used  in  theatres  and  the  globe  light  are 
examples  of  these. 

The  Welsbach  incandescent  gas  burner  now  has  a  very  ex- 
tended use.  It  consists  of  a  Bunsen  burner,  with  a  cap  (mantle) 
of  asbestos  gauze  material  (rendered  non-inflammable  by  chemical 
treatment  with  sulphate  of  zirconium)  suspended  in  the  non- 


WARMING    AND    LIGHTING  259 

luminous  flame;  the  gauze  mantle  becomes  incandescent  and 
gives  a  brilliant  light,  far  whiter  and  steadier  than  the  ordinary 
gas  flame.  The  flame  should  be  enclosed  in  a  chimney.  The 
illuminating  power  is  very  high  for  the  amount  of  gas  consumed, 
and  the  heat  given  off  is  far  less  than  with  an  ordinary  gas  flame. 
If  such  burners  came  into  general  use,  a  cheap  form  of  gas 
containing  no  illuminants  could  be  supplied;  for  heat  and  not 
light  is  required  in  the  flame.  The  cheap  gas  would  also  lead 
to  a  more  general  adoption  of  gas-heating  and  gas-cooking, 
and  thus  to  the  partial  solution  of  the  smoke  question. 

The  Welsbach  incandescent  gas  burner  is,  hygienically,  by 
far  the  best  form  of  lighting  by  coal  gas. 

In  the  albo-carbon  light,  the  vapour  of  naphthalene  is  burnt 
in  the  coal  gas,  and  a  brilliant  white  light  is  produced.  The 
naphthalene,  which  is  solid  at  ordinary  temperatures,  is  placed  in 
a  reservoir  connected  with  the  gas  burner,  and  this  reservoir 
must  be  heated  by  a  small  gas  jet  or  by  strips  of  metal  extending 
from  the  flame.  The  vapour  of  naphthalene  must  not  be  allowed 
to  escape  into  the  air,  as  its  odour  is  most  offensive. 

One  cause  of  waste  and  imperfect  combustion  with  flat  flame 
burners  is  the  constant  alterations  of  pressure  in  the  gas  pipes 
and  mains.  At  one  period  of  the  day  the  pressure  may  be  less 
than  one  inch  of  water,  whilst  at  another  it  may  be  3  inches  or 
more.  Consequently  the  flat  flame,  which  is  steadily  burning 
under  the  low  pressure,  at  the  high  pressure  is  flaring  and  singing; 
more  gas  is  issuing  from  the  burner  than  can  be  perfectly  burnt, 
and  unconsumed  carbon  is  given  off  from  the  flame  to  pollute 
the  air  and  blacken  everything  around.  To  control  these  varia- 
tions in  pressure,  gas  governors  or  regulators  are  employed. 
In  the  larger  form,  the  governor  is  fixed  close  to  the  meter, 
and  controls  the  pressure  throughout  the  house  pipes;  whilst 
a  small  form  is  made  as  part  of  each  individual  burner.  The 
best  kind  of  governor  acts  automatically;  by  the  action  of 
valves  an  increased  pressure  narrows  the  lumen  of  the  channel 
through  which  gas  passes,  and  a  diminished  pressure  widens 
it.  Single  burner  governors  are  also  found  to  answer  fairly 
well. 

Acetylene  gas  (C2H2),  generated  by  the  action  of  carbide 
of  calcium  on  water  (CaC2-HH20=-CaO-(-C2H2),  furnishes  a 
powerful  white  light ;  but  its  use  is  not  unattended  with  danger, 
unless  great  care  is  exercised. 


260  HYGIENE  AND  PUBLIC  HEALTH 

Petyolcum  Oils. — By  the  distillation  ol  crude  petroleum  oil 
an  oil  suitable  for  burning  in  lamps — commonly  called  crystal 
oil  or  kerosene — is  obtained.  In  the  distillation,  a  volatile 
spirit  (benzoline)  and  heavy  oils,  some  of  which  are  solid  from 
containing  paraffin,  are  also  obtained,  and  are  separated  from 
the  lamp  oil. 

Lamp  oil  contains  the  hydro-carbons  previously  mentioned, 
and  gives  off  an  inflammable  vapour  which  at  a  certain  tempera- 
ture takes  fire.  This  temperature  varies  for  different  specimens 
of  oil,  and  is  called  the  "  flashing  point." 

A  select  Committee  appointed  by  Parliament  attributed  the 
chief  danger  from  lamp  explosions  to  cheap  lamps  of  defective 
design,  and  they  recommended  that  the  flash  point  (Abel  close 
test)  should  be  raised  from  'j-^°  F.  (the  limit  defined  by  the 
Petroleum  Act,  1879)  to  100°  F.;  that  statutory  powers  should 
be  created  to  enable  the  Secretary  of  State  to  issue  orders  affect- 
ing the  manufacture  and  sale  of  lamps;  and  that  information 
should  be  spread  among  the  public  as  to  the  nature  of  petroleum 
and  the  management  of  lamps.  In  the  suggestions  issued  by 
the  London  County  Council,  it  is  pointed  out  that  the  flashing 
point  of  ordinary  petroleum  oil  is  a  little  above  73°  F.,  that  the 
oil  in  the  reservoirs  of  lamps  is  rarely  heated  above  100°  F., 
and  that  the  best  safeguard  against  accident  is  therefore  never 
to  burn  oil  which  has  a  flashing  point  of  less  than  100°  F.,  which 
oil  should  be  sold  as  cheaply  as  low  flash  oil.  Lamps,  too, 
should  be  strongly  made,  and  kept  thoroughly  clean;  especially 
should  the  reservoir  and  burner  be  strong;  the  latter  should 
screw  into  the  collar,  and  the  base  of  the  lamp  should  be  broad 
and  heavy.  The  wick  should  be  soft,  and  should  reach  to  the 
bottom  of  the  reservoir,  and  just  fill  the  wick  tube;  it  should 
be  frequently  renewed,  and  before  being  put  into  a  lamp  it 
should  be  dried  at  a  lire,  and  immediately  soaked  with  oil.  The 
reservoir  should  be  filled  with  oil  before  the  lamp  is  lit,  and  the 
burner  made  clean  before  lighting;  the  wick  when  lit  should 
be  partially  turned  down,  and  then  gradually  raised;  the  wick 
should  not,  however,  be  left  turned  down;  lamps  that  have 
no  extinguishing  apparatus  should  be  put  out  by  turning  down 
the  wick  until  there  is  only  a  small  flickering  flame,  and  a  flat 
piece  of  metal  should  then  be  placed  on  the  top  of  the  chimney, 
so  as  to  close  it  entirely;  finally,  cans  or  bottles  used  for  oil 
should  be  free  from  water  and  dirt,  and  kept  closed. 


WARMING   AND    LIGHTING 


261 


Owing  to  improvements  in  lamps,  and  to  the  prohibition  of 
the  sale  of  highly  inflammable  oils,  the  danger  of  explosion 
is  now  slight.  Lamp  explosions  may  occur  when,  from  any 
cause,  the  vapour  over  the  oil  in  the  reservoir  comes  in  contact 
with  the  flame  of  the  lamp,  as  through  defects  in  the  lamp  or  by 
blowing  down  the  chimney  past  an  ill-fitting  wick,  etc.  But 
the  best  duplex  lamps  (the  Defries  and  other  safety  lamps) 
are  now  sold  with  extinguishers,  and  with  an  ingenious  arrange- 
ment by  which,  if  the  lamp  is  overturned,  the  flame  is  immedi- 
ately extinguished. 

Lamp  accidents  generally  appear  to  arise  from  the  use  of 
cheap  lamps  of  defective  design,  leading  to  a  leakage  of  oil 
through  imperfect  connections  and  fittings.  The  oil  may  thus 
become  ignited.  Sometimes  the  lamp  is  upset  from  its  instability, 
or  broken  owing  to  the  fragile  character  of  the  reservoirs. 

The  "  Petrolite  "  lamp  is  a  safe  lamp  of  high  candle-power. 
In  this  lamp  the  petrol  is  absorbed  by  a  block  of  highly  ab- 
sorbent stone,  and  the  petrol  vapour,  being  made  to  mix  with 
air,  furnishes  a  hot  flame,  which,  playing  upon  a  mantle,  pro- 
duces a  brilliant  incandescent  light.  In  the  event  of  the  lamp 
being  upset  the  flame  is  immediately  extinguished. 

The  Kitson  light  has  been  used  successfully  for  the  purpose 
of  public  street  lighting.  This  light  is  obtained  by  the  auto- 
matic vaporization  of  petroleum  oil,  the  mixture  of  air  with  this 
oil  by  injection,  and  the  impingement  of  the  flame  upon  a  specially 
made  mantle.  The  diffusive  power  of  this  light  exceeds  both  the 
electric  arc  light  and  the  incandescent  gaslight,  it  is  cheaper  than 
either,  and  the  roads  have  not  to  be  taken  up — as  when  electric 
light  or  gaslight  is  employed. 

Colza  oil  does  not  give  off  any  inflammable  vapour,  but  it  is 
much  dearer  than  kerosene,  and  the  illuminating  power  is  less. 
Colza  oil  lamps  require  more  care  in  trimming  than  kerosene 
lamps.  Kerosene,  like  coal  gas,  gives  off  sulphurous  acid  when 
burned,  but  colza  oil  does  not. 

Candles,  especially  the  cheaper  kinds,  give  off  much  imcon- 
sumed  carbon,  by  reason  of  their  low  melting  point  admitting  of 
volatile  products  being  given  off  before  the  fats  reach  the  flame 
and  are  properly  consumed. 

Electric  Light.— The  electric  light  presents  the  following 
advantages  over  coal  gas,  oil,  and  candles.  There  is  no  con- 
sumption of  oxygen,  there  are  no  products  of  combustion  to 


262 


HYGIENE    AND    PUBLIC   HEALTH 


pollute  the  air,  and  the  heat  produced  is  relatively  slight.  The 
light  of  the  arc  light  is  not  yellow,  but  white.  It  precisely 
resembles  solar  light  in  being  rich  in  the  violet  and  the  ultra 
violet  rays.  Plants  grow  and  flower,  and  fruit  ripens,  when 
exposed  to  this  light,  just  as  they  do  in  the  sunlight;  whilst 
photographs  can  be  taken  as  easily  by  the  arc  electric  light  as  by 
daylight. 

The  electric  current  can  be  produced  by  batteries,  accumu- 
lators and  dynamo  machines,  and  is  conveyed  in  copper  wires 
to  the  spots  where  illumination  is  required. 

In  the  arc  light,  which  is  suitable  for  lighting  streets,  squares, 
and  large  halls  and  buildings,  the  illumination  is  produced  by 
the  passage  of  the  current  through  two  carbon  rods  brought 
into  close  apposition.  The  resistance  offered  to  the  passage 
of  the  current  across  the  space  intervening  between  the  points 
of  the  carbon  rods  creates  sufficient  heat  to  cause  the  carbon 
points  to  become  brilliantly  incandescent.  The  light  is  ex- 
tremely dazzling,  and  is  productive  of  injurious  effects  on  the 
eyes  of  those  who  are  much  exposed  to  its  influence. 

The  incandescent  lamps  are  best  suited  for  domestic  use. 
In  these  the  current  is  passed  through  a  loop  of  filamentous 
carbon  enclosed  in  a  small  glass  globe  exhausted  of  air,  or  filled 
with  some  gas  (such  as  nitrogen)  which  does  not  support  com- 
bustion. The  resistance  offered  by  the  carbon  to  the  passage  of 
the  current  raises  it  to  a  white  heat. 

Metallic  filaments  are  now  largely  used  instead  of  carbon. 
These  metallic  filament  lamps  give  a  far  more  powerful  and 
whiter  light  with  less  current  than  do  the  carbon  lamps. 

The  extent  to  which  different  modes  of  lighting  affect  the 
atmosphere  may  be  thus  represented: — ■ 


Amount 
Consumed. 

Candle 
Power. 

Oxygen 
Removed. 

CO.j  Pro- 
duced. 

Heat 
Calories 
Produced. 

Tallow  candles  . 

2,200  grs. 

16 

10-7  C.  ft. 

7-3 

1,400 

Sperm  candles  . 

1,740    .. 

16 

9-6      ., 

6-5 

1. 137 

Paralifin  oil  lamp 

992    .. 

16 

6-2       ,, 

4-5 

1,030 

Kerosene  oil  lamp 

9"9     .. 

16 

5-9     .. 

4-1 

1,030 

Coal  gas,  No.  5   bat- 

wing  burner    . 

5-5  eft. 

ir, 

6-5      ., 

2-S 

1,104 

Electric  incandescent 

16 

o-o      ,, 

o-o 

37 

CHAPTER  V 
SOILS  AND  BUILDING  SITES 

The  health  of  a  locaHty  is  often  influenced  by  the  nature  of  the 
soil  on  which  the  houses  are  built;  and  it  has  been  truly  said 
that  if  the  site  is  unhealthy,  the  dwelling  cannot  be  made  healthy. 
It  is  generally  believed  that  the  most  porous  soils — the  gravels 
and  sands — are  the  healthiest,  because  they  are  the  driest,  and 
this  view  is  in  the  main  correct;  but  owing  to  their  porosity 
they  are  readily  polluted  by  leaky  drains  and  cesspools. 

The  porous  or  permeable  soils — the  loose  sands  and  gravels 
and  the  sandstones — are  capable  of  holding  considerable  volumes 
of  air  or  water.  Even  the  impermeable  rocks — the  granites  and 
metamorphic  rocks,  the  dense  clays  and  hard  limestones  and 
dolomite — are  not  wholly  unabsorbent,  but  comparatively 
speaking  they  may  be  looked  upon  as  impermeable.  Between 
these  and  the  porous  sands  and  gravels  are  all  stages  of  gradation. 
The  surface  soils  which  usually  lie  upon  the  denser  kinds  of  rocks, 
of  which  they  are  to  a  considerable  extent  the  weathered  frag- 
ments, are  always  more  or  less  porous.  The  interstices  or 
interspaces  between  the  particles  of  the  porous  soils  are  neces- 
sarily occupied  by  air  (ground  air),  or  at  a  varymg  depth  by  water 
(ground  water).  When  there  is  air  as  well  as  water  between 
the  interstices,  the  water  is  nothing  more  than  "  ground  moisture," 
but  when  the  interstices  are  completely  filled  with  water,  then 
the  "  ground  water  "  has  been  reached.  The  ground  water  is 
derived  from  the  rain  which  percolates  the  soil  until  it  reaches 
an  impervious  stratum  which  prevents  it  penetrating  any 
further.  Above  the  level  of  this  subterranean  water  the  in- 
terstices of  the  soil  are  mainly  filled  with  air. 

The  depth  at  which  the  ground  water  will  be  reached  in  any 
soil  depends  on  a  variety  of  circumstances — the  elevation  of 
the  district  and  its  surroundings,  the  depth  of  the  impermeable 

263 


264  HYGIENE    AND    PUBLIC   HEALTH 

stratu'ii  from  the  surface,  and  the  ease  with  which  the  under- 
ground water  reaches  its  natural  outlet  in  spring,  river,  or  sea 
In  the  low-lying  plains  and  valleys  the  underground  water 
is  not,  as  a  rule,  far  from  the  surface  of  the  earth.  Its  level 
is  not  constant,  as  we  have  seen  in  the  chapter  on  Water  (p.  21), 
but  is  always  changing.  After  heavy  rainfall  the  level  ma}^  rise; 
and  there  is  usually  a  periodic  rise,  commencing  in  the  late 
autumn,  due  as  explained  before  to  the  increased  percolation 
of  rain-water  through  the  autumn  and  winter,  and  its  diminution 
through  the  drier  spring  and  summer  months.  The  lateral 
movement  of  the  ground  water  is  generally  towards  the  nearest 
watercourses,  the  sea,  wells,  fissures  in  rocks,  shafts  of  coal- 
mines, etc. 

The  rise  and  fall  of  the  ground  water  cause  corresponding 
movements  in  the  ground  air  which  lies  above  it.  As  the  ground 
water  rises,  it  occupies  the  space  formerly  occupied  by  the  ground 
air,  and  the  latter  is  slowly  expelled  from  the  surface  of  the  earth: 
as  the  ground  water  sinks,  air  is  drawn  in  to  occupy''  its  place, 
to  be  again  expelled  when  the  water  rises.  There  are  other 
factors  influencing  the  movements  of  the  ground  air  which 
have  no  effect  on  those  of  the  ground  water.  The  principal 
of  these  are  alterations  in  barometrical  pressure,  sudden  varia- 
tions in  temperature,  and  the  perflating  action  of  the  wind. 

It  is  thus  seen  that  the  porous  surface-layers  of  the  earth  act 
as  a  sort  of  lung,  slowly  taking  air  in  and  slowly  expelling  it 
again.  This  action  is  no  doubt  greatly  increased  on  the  small 
surface  of  ground  covered  by  a  house.  In  winter,  when  the 
adjacent  surface  of  ground  may  become  ice-locked,  the  heat 
of  the  building  and  the  aspirating  action  of  fires  must  tend  to 
draw  air  in  large  volumes  through  the  soil  beneath  the  dwelling, 
unless  the  site  is  covered  with  an  impenetrable  layer  of  asphalt 
or  cement  concrete. 

The  ground  air  is  generally  moist  and  always  impure.  The 
amount  of  moisture  depends  on  the  proximity  of  the  ground 
water  to  the  surface  of  the  soil;  if  this  is  but  a  few  feet  from 
the  surface,  the  ground  air  is  saturated  with  moisture;  if  at 
great  depths,  the  moisture  is  not  excessive.  But  the  ground 
near  the  surface  of  the  earth  in  most  parts  of  the  world  is 
damp,  even  after  a  prolonged  drought,  owing  to  capillary  at- 
traction and  evaporation  from  the  surface  of  the  ground  water. 
TJic  imjnirity  of  the  ground  air  is  due  to  the  decomposition  of 


SOILS    AND    BUILDING    SITES  265 

the  various  orp;anic  matters  wliich  are  washed  into  the  soil  by 
the  rain,  or  which  are  naturally  present  in  some  marshy  soils. 
These  latter  are  usually  of  vegetable  origin.  The  impurity  of 
the  ground  air  even  in  virgin  or  natural  soils  is  shown  by  a  great 
diminution  in  oxygen  and  an  enormous  increase  in  carbonic  acid. 
In  the  neighbourhood  of  houses,  however,  the  foulness  of  the 
ground  air  is  often  due  to  animal  contaminations,  and  these 
may  be  of  the  most  dangerous  description.  Leaking  cesspools, 
sewers  and  drains  allow  animal  filth,  and  possibly  infected  ex- 
cretions, to  pollute  the  water  and  air  in  the  soil;  graveyards 
and  cemeteries  permit  decomposing  animal  bodies  to  exercise  a 
similar  pollution;  whilst  the  organic  effluvia  arising  from  made 
soils — soils  formed  of  old  deposits  of  house  refuse  and  dry  rubbish 
— seriously  imperil  the  health  of  the  inmates  of  the  houses  built 
over  them. 

The  organic  matters,  whether  of  vegetable  or  animal  origin, 
are  decomposed  in  the  soil  by  micro-organisms.  These  organisms 
grow  in  the  presence  of  such  food  material,  breaking  it  up  into 
simpler  combinations — carbonic  acid,  ammonia,  and  water — and 
thus  by  the  processes  of  fermentation  and  putrefaction  exert  a 
purifying  action,  and  at  the  same  time  convert  the  complex 
organic  bodies  into  products  best  fitted  to  be  assimilated  by  the 
growing  vegetation.  The  presence  of  oxygen,  warmth,  and 
moisture  is  essential  to  the  proper  carrying  out  of  these  pro- 
cesses. The  oxygen  is  present  in  the  ground  air,  the  moisture  is 
derived  from  the  ground  water,  and  the  temperature  of  the  soil  is 
usually  suitable,  except  during  long  frosts  or  in  very  cold  climates. 

It  is  thus  seen  that  surface  soil  acts  as  a  vast  natural  laboratorj^ 
f  or  the  purification  and  utilization  of  effete  animal  and  vegetable 
matters. 

The  draining  of  damp  soils,  so  as  to  permanently  lower  the 
level  of  the  subsoil  water,  is  a  measure  much  needed  in  the 
interests  of  health.  In  the  first  place,  it  is  desirable  to  avoid 
great  fluctuations  in  the  level  of  the  ground  water;  and  this 
can,  to  a  certain  extent,  be  accomplished  by  subsoil  drainage, 
which  at  once  carries  off  the  water  when  it  rises  to  the  level  at 
which  the  drains  are  laid.  When  the  subsoil  water  rises,  it  forces 
the  ground  air  before  it  and  out  of  the  soil;  not  only  this,  but  it 
causes,  when  it  arrives  within  a  few  feet  of  the  surface,  a  damp- 
ness of  the  atmospheric  air  and,  by  evaporation,  a  cooling  of  the 
air.     The    moisture    ascends   by   capillary    attraction    into    the 


266  HYGIENE  AND  PUBLIC  HEALTH 

walls  of  houses,  to  be  subsequently  evaporated  from  the  surfaces 
of  the  internal  walls;  in  this  evaporation  heat  is  absorbed  from 
surrounding  objects,  and  the  air  of  a  house  with  damp  walls 
is  not  only  moist,  but  cold. 

This  condition  of  dampness  in  the  site  and  air  of  a  house  is 
one  credited  by  universal  experience  with  the  production  of 
rheumatism,  catarrh,  neuralgia,  and  affections  of  a  bronchial 
and  pulmonary  nature,  and  is  probably  a  predisposing  factor  to 
diphtheria,  measles  and  whooping-cough. 

The  researches  of  Dr.  Bowditch,  of  Boston,  U.S.A.,  and  of 
Dr.  Buchanan  in  this  country,  have  conclusively  shown  that 
there  is  an  intimate  connection  between  moisture  of  soil  and 
phthisis.  Such  diseases  were  shown  by  Dr.  Buchanan  to  be 
much  less  fatal  in  certain  English  towns  after  they  had  been 
sewered  and  the  soil  consequently  drained,  than  they  had  been 
previously  to  the  construction  of  the  sewer  works.  Where  the 
drying  of  the  subsoil  was  considerable,  the  deaths  from  phthisis 
were  reduced  to  two-thirds,  or  even  one-half,  of  what  they  had 
previously  been. 

Professor  Pettenkofer  has  shown  a  relation  between  the 
height  of  the  ground  water  and  epidemic  outbreaks  of  enteric 
fever  in  Munich;  and  he  demonstrated  that  when  the  water 
in  the  wells  was  at  its  lowest  level,  especially  after  a  rapid  fall 
succeeding  an  unusually  high  level,  the  disease  was  most  preva- 
lent in  that  city.  Munich  is  built  on  a  porous  sandy  soil,  at  that 
time  riddled  with  cesspools,  of  which  the  contents  rapidly  soaked 
into  the  surrounding  soil;  so  that  it  is  conceivable  that,  after 
heavy  rainfall,  liquid  cesspool  filth  would  be  carried  into  the 
wells,  and  an  outbreak  of  enteric  fever  might  result  two  or 
three  weeks  after  the  specific  pollution  of  the  drinking  water, 
and  when  the  level  of  the  ground  water  had  fallen. 

In  this  country,  however,  no  invariable  relation  has  been 
found  to  exist  between  the  onset  of  enteric  fever  epidemics  and 
low  level  of  ground  water. 

But  in  considering  this  subject,  it  must  not  be  forgotten 
that  there  are  other  factors,  such  as  temperature,  condition 
of  the  soil  as  regards  moisture  and  pollution,  etc.,  which  may 
have  a  more  direct  bearing  on  health  conditions  than  the  level 
of  the  ground  water.  The  right  view  appears  to  be  that  fluctua- 
tions of  level  are  of  but  little  consequence  in  themselves,  but 
that  by  favouring  pollution   of  water  in  wells,   or  by  forcing 


SOILS   AND    BUILDING   SITES  267 

impure  .ground  air  into  houses,  thoy  may  cxcrrise  a  considerable 
influence  on  health. 

Pcttenkofer  has  also  recorded  the  occasional  coincidence  of 
cholera  outbreaks  with  a  low  state  of  the  ground  water.  Epidemic 
diarrhoea  occurring  in  summer  and  autumn  has  also  been  shown  to 
be  related  to  certain  soil  conditions,  and  the  prevalence  of  yellow 
fever  is  also  generally  held  to  be  influenced  by  soil,  which  being 
retentive  of  surface  moisture  favours  the  breeding  of  mosquitoes. 

The  connection  between  malaria  and  damp  marshy  soils 
capable  of  holding  stagnant  water — the  breeding  grounds  of  the 
mosquito  {Anopheles) — -is  more  firmly  established.  In  many 
instances  malarious  districts  have  been  rendered  healthy  by 
subsoil  drainage  or  by  tree  planting.  In  hot  climates,  trees 
and  vegetation  abstract  large  quantities  of  water  from  the  soil, 
and  this  is  evaporated  from  their  green  leaves.  It  has  been  cal- 
culated that  an  oak-tree  evaporates  eight  and  a  half  times  the 
rainfall  over  the  area  it  covers,  whilst  the  Eucalyptus  f^lobulus 
absorbs  and  evaporates  eleven  times  this  amount.  The  latter 
tree  has  been  extensively  planted  in  many  malarious  districts, 
with  the  effect  of  rendering  them  more  healthy;  for  the  soil 
has  been  dried  by  permanently  lowering  the  level  of  the  subsoil 
water,  and  the  moisture  factor  being  withdrawn,  the  mosquitoes 
are  no  longer  provided  with  an  environment  favourable  to  their 
propagation.  It  must  be  remembered  also  that  moisture 
favours  decomposition  of  putrefiable  material;  therefore  a  dry 
soil  is  cleaner,  and  the  ground  air  is  purer  than  in  the  case  of 
a  damp  one. 

In  very  damp,  marshy  districts  it  is  advisable  that  houses 
should  be  raised  above  the  ground  on  arches  open  to  the  air; 
or,  in  the  case  of  wooden  houses,  on  piles.  Moist  ground 
immediately  around  the  site  of  the  house  should  even  then  be 
drained  and  filled  in,  and  the  surface  covered  with  grass  kept 
closely  cut.  Excessive  vegetation  should  be  cleared  away  and 
burnt. 

Low-lying  alluvial  tracts  are  not  desirable  sites  for  residences, 
for  the  ground  water  is  either  very  near  the  surface,  or  the  ground 
is  water-logged  for  many  months  of  the  year;  and  the  site  is 
damp,  subject  to  fogs,  and  affords  an  unreliable  foundation  for 
buildings.  When  an  alluvial  site  is  on  the  borders  of  a  river, 
it  is  liable  to  flooding,  and  it  becomes,  extremely  difficult  to 
secure  dry  basements.     There  is,  moreover,  great  difficulty  in 


268  HYGIENE    AND    PUBLIC   HEALTH 

providing  efficient  drainage  for  the  sewage  of  the  house,  especially 
where  houses  have  basements. 

From  the  above  remarks  it  follows  that  for  the  choice  of  a 
site  for  a  house,  a  dry,  fairly  open  and  sunny  situation,  and  a 
pure,  dry  and  porous  soil  are  desirable,  in  an  elevated  position 
and  on  a  gentle  slope  favouring  natural  drainage  both  on  the 
surface  and  in  the  subsoil.  Vallej^s  lying  in  the  direction  of 
the  prevalent  winds  are  drier  and  therefore  more  healthy  than 
those  lying  in  other  directions.  In  cold  and  temperate  climates, 
sands  and  gravels,  if  of  considerable  depth,  and  not  water- 
logged by  reason  of  a  low  situation  or  underlying  clay  per- 
mitting ground  water  to  rest  upon  it,  are  the  healthiest,  because 
the  warmest  (most  absorbent  of  heat)  and  the  driest.  Gravel 
in  patches  has  sometimes  a  clayey  or  loamy  matrix,  and  may 
thus  be  itself  retentive  of  water.  Clayey  soils  are  cold,  because 
little  absorbent  of  heat;  the}^  are  also  damp  from  the  retention 
of  moisture,  and  therefore  not  so  healthy  as  the  more  permeable 
soils.  The  disadvantages  of  living  on  clay  are  materially  reduced 
by  elevation  with  sufficient  siu-face  falls  to  favour  good  surface 
drainage.  Chalk  is  usualty  dry,  but,  being  little  absorbent 
of  heat,  is  cold.  Generally  speaking,  soils  may  be  classified, 
as  follows,  in  the  order  of  their  healthiness: — Gravel,  sand, 
sandstone,  chalk,  rocks  (granite,  clay-slate,  limestone),  loam 
and  stiff  clay,  alluvial  land  (low-lying),  made  soil.  In  hot 
climates  sands  are  excessively  hot,  unless  covered  with  herbage, 
which  protects  from  the  sun's  rays  and  cools  the  air  by  evapora- 
tion of  moisture.  Trees  by  favouring  the  stagnation  of  air  tend 
to  check  evaporation  from  the  ground,  and  thus  favour  damp- 
ness. They  may  be  utilized,  at  a  sufficient  distance  from  the 
house,  for  sheltering  from  the  north  and  east  winds. 

In  towns,  made  soils — which  result  from  the  filling  in  with 
household  refuse  and  other  rubbish  of  low-lying  sites  or  excava- 
tions made  for  the  purpose  of  removing  the  virgin  gravel,  etc. 
— should  be  avoided. 

If  the  soil  is  damp,  the  entire  site  below  the  foundations 
should  be  drained,  by  laying  unglazed  agricultural  pipes  in 
trenches  filled  in  above  with  pebbly  gravel.  This  allows  free 
percolation  of  water  into  the  pipes,  through  the  porous  material 
of  which  they  are  constructed  and  between  their  ends,  which 
are  laid  in  apposition  but  not  jointed.  The  subsoil  drains 
should  not  bo  connected  with  anj^  soil  drain,  sewer,  or  cesspool. 


SOILS   AND   BUILDING   SITES  269 

but  sliould  discharge,  if  possible,  into  a  ditch  or  stream.  Wlierc 
this  is  not  possible,  the  subsoil  drain  may  be  connected  with 
a  house  drain  or  sewer  after  proper  disconnection  has  been 
practised,  as  for  house  drains  (see  page  107).  In  open  soils,  such 
as  sands,  a  single  drain  will  lower  the  level  of  the  ground  water 
over  a  considerable  area,  whereas  in  stiff  close  soils  numerous 
drains  are  necessary.  The  ground  water  should  perferably  not 
reach  to  within  10  feet  of  the  surface  of  any  site  on  which  a 
dwelling  is  to  be  erected. 

To  prevent  the  entrance  of  ground  air  and  moisture,  the 
entire  site  of  the  house,  within  the  external  walls,  should  be 
covered  with  a  layer  of  cement  concrete,  6  inches  thick,  rammed 
solid;  and  the  surface  thus  formed  should  be  grouted  over  with 
cement.  In  large  town  houses  with  basement  floors  below  the 
street  level,  the  cemented  surface  when  asphalted,  tiled,  or 
paved  with  solid  wood-block  flooring  may  conveniently  form 
the  finished  flooring;  being  free  from  cracks  and  crevices,  it 
can  afford  no  lodgment  for  cockroaches  or  other  vermin,  which 
so  frequently  infest  the  lower  storeys. 

In  houses  without  cellars,  more  especially  where  the  site  is 
not  concreted  over,  the  lower  floors  should  be  raised  2  feet  above 
the  surface  of  the  ground,  and  the  intervening  space  should  be 
well  ventilated  through  air  grids  or  air  bricks  in  the  external 
walls. 

Great  care  must  be  taken  that  the  excavations  for  the  house 
foundations  are  protected  from  the  access  of  water  by  proper 
drainage  where  necessary,  otherwise  they  serve  to  store  moisture 
and  occasion  serious  dampness  in  basements.  If  the  building 
is  on  sloping  ground,  it  should  be  well  protected  from  moisture 
on  the  side  towards  which  the  surface  waters  flow.  The  building 
should  be  erected  on  a  uniform  bed — not  partly  on  gravel  and 
partly  on  clay,  for  instance,  as  there  would  then  be  unequal 
resistance  to  the  superincumbent  pressure.  A  chalk  foundation 
should  be  first  well  tested,  as  cavities  or  pipes  therein  may  lead 
to  subsidence.  Clay  slopes  are  undesirable  sites,  because  the 
clay  may  shrink  and  crack  after  a  prolonged  drought,  or  swell 
and  soften  after  much  rain,  and  thus  injure  the  building. 

A  wall  built  of  ordinary  building  bricks  and  mortar  is  very 
porous,  and  capable  of  absorbing  large  quantities  of  water.  Each 
brick  can  hold  about  16  ounces  of  water. 

To  obviate  damp  from  the  ground  rising  in  the  brick  walls, 


270 


HYGIENE  AND  PUBLIC  HEALTH 


a  horizontal  damp-proof  course  of  slates  bedded  in  cement,  a 
|-inch  layer  of  asphalt,  or  slabs  of  perforated  glazed  stoneware, 
should  be  inserted  in  the  wall,  slightly  above  the  level  of  the 
ground  adjoining.  The  stoneware  slabs  answer  a  double  pur- 
pose; they  are  not  only  damp-proof,  but  the  perforations  afford 
an  air  passage  through  the  wall,  and  ventilate  the  space  under 
the  flooring — a  very  necessary  precaution  to  prevent  dry  rot  in 
timbers  and  joists. 

Damp-proof  courses  may  even  be  inserted  in  the  walls  of  old 
buildings,  by  removing  a  course  of  bricks  piecemeal,  after  under- 
pinning the  walls,  and  then  inserting  air  bricks  in  sections. 


STONE 


'CONCRETE 


Fig.  38. —  House  Foundation  with  Damp  rRooF  Course  in  Wall 
AND  Dry  Area. 


The  external  house  walls,  when  these  pass  below  the  surface 
of  the  ground,  must  be  separated  from  the  moist  earth  by  an 
"  open  "  area  extending  upwards  from  the  footings  or  founda- 
tion. Where  space  will  not  permit  of  an  open  area,  a  "  dry  " 
area  should  be  formed  (fig.  38). 

This  is  merely  an  area  a  few  inches  wide,  to  prevent  the 
moist  earth  coming  in  contact  with  the  wall,  which  is  carried  up 
well  above  the  surface  of  the  ground,  and  is  covered  at  the  top; 
or  a  double  (cavity)  wall  may  be  formed  below  the  ground  level 
so  as  to  enclose  a  narrow  vertical  air  space.  This  arrangement 
necessitates  two  damp-proof  courses — the  lower  just  above  the 
footings,  and  the  upper  across  the  outer  portion  of  the  cavity 
wall  shghtly  above  the  ground  level.  These  provisions  are 
necessary  to  prevent  damp  cellars  and  basements. 


SOILS   AND    BUILDING    SITES  27I 

In  very  exposed  situations  the  outer  walls  of  houses  are  liable 
to  become  damp  from  driving  rain.  The  usual  remedies  consist 
in  covering  the  walls  with  slates  or  glazed  tiles,  set  in  cement, 
or  coating  the  brickwork  with  Portland  cement,  which,  being 
impervious  to  moisture,  answer  extremely  well. 

House  walls  constructed  of  soft  porous  bricks  jointed  with  bad 
mortar  are  especially  liable  to  become  damp  from  driving  rain. 
If  both  bricks  and  mortar  are  soft  and  rotten,  the  wall  should 
be  coated  with  cement;  if  the  bricks  are  sound,  but  the  mortar 
decayed,  the  wall  should  be  repointed  with  good  cement.  Good 
lime  mortar  should  contain  one  part  of  recently  burnt  lime  to 
three  parts  of  sand.  Cement  mortar  consists  of  one  part  of 
cement  to  four  of  sand. 

Sometimes  in  new  houses  the  wall-papers  are  stained  from 
temporary  dampness,  which  is  due  to  the  evaporation  of  the 
water  in  the  new  bricks  and  mortar  ("  building  water  "). 

Another  common  cause  of  damp  walls  is  defective  gutters  to 
the  roof,  or  broken  or  otherwise  damaged  rain-water  pipes.  In 
both  these  cases  water  drips  down  the  outer  walls,  and,  soaking 
through  the  bricks  and  mortar,  causes  a  serious  dampness. 

In  most  towns  the  local  authorities  now  compel  house  owners 
to  pave  the  ground  immediately  around  dwellings.  The  best 
material  for  yard-paving  is  cement-concrete,  the  Portland  cement 
being  first  well  dried  and  then  thoroughly  mixed  with  clean  sharp 
sand.  Asphalt  also  makes  a  good  paving.  Other  materials  used 
are  blue  glazed  Staffordshire  bricks  and  York  flagstones,  but  in 
these  cases  a  good  hard  and  smooth  bottom  of  concrete  should 
first  be  laid. 

There  is  probably  some  relation  existing  between  the  sanitary 
condition  of  streets  in  urban  districts  and  the  prevalence  of 
summer  diarrhoea.  The  desirability,  from  a  public  health  stand- 
point, of  perfectly  sanitary  roads  is  now  recognized.  The  sanitary 
condition  of  streets  depends  not  merely  upon  the  use  made  of 
them,  but  also  upon  the  materials  of  which  they  are  constructed, 
and  the  manner  in  which  they  are  kept,  as  regards  the  frequent 
removal  of  slop  and  dust. 

A  perfectly  good  road  should  have  a  firm  dry  foundation, 
with  a  hard,  tough,  and  compact  surface,  the  latter  being  neither 
too  flat  to  allow  water  to  stand,  nor  too  convex  to  inconvenience 
traffic. 

The  substitution  of  mechanical  power  for  horse  traction  would 


272  HYGIENE  AND  PUBLIC  HEALTH 

be  a  great  sanitary  advancement,  and  in  the  matter  of  street 
cleansing  would  effect  a  great  saving  of  expense.  The  usual 
method  of  bringing  trade  refuse  out  into  the  streets,  and  the 
general  littering  which  results,  is  a  practice  which  ought  not  to 
be  allowed.  In  large  urban  communities  a  considerable  propor- 
tion of  the  population  spend  the  major  part  of  the  day  in  the 
streets,  and  their  houses  practically  abut  upon  them.  The 
necessity,  therefore,  of  keeping  the  streets  as  wholesome  as 
possible  by  guarding  them  from  all  avoidable  animal  and  vegetable 
pollution  by  frequent  scavenging  is  obvious,  and  makes  itself 
specially  felt  in  the  hot  weather,  when  the  odours  given  off  from 
badly  scavenged  streets  are  most  marked,  and  the  suspended  dust 
(consisting  of  powdered  horse-dung,  etc.)  is  highly  unpleasant  and 
irritating  to  the  eyes  and  throat.  Frequent  flushing  by  water 
vans  or  by  hose  has  possibly  some  effect  in  reducing  the  preva- 
lence of  summer  diarrhoea. 

The  chief  kinds  of  road  paving  are  macadam,  granite  setts, 
wood,  and  asphalt.  Macadam  creates  by  far  the  most  mud  and 
dirt,  and  is  therefore  expensive  to  maintain  and  cleanse;  it  is 
noisy  and  very  absorbent.  Constant  watering  in  dry  weather, 
and  cleansing  of  the  surface  at  all  times,  are  absolutely  necessary 
to  maintain  macadam  roads  in  good  condition. 

Granite  setts  furnish  a  most  enduring  pavement,  easily  and 
cheaply  repaired  and  cleansed,  and  practically  non-absorbent. 
The  great  objection  to  this  form  of  pavement  is  the  noise  arising 
from  the  wheels  of  the  vehicles  and  the  iron  shoes  of  the  horses 
striking  upon  it.  The  noise  can  be  diminished  by  running  the 
joints  with  asphaltic  composition  instead  of  the  ordinary  Portland 
cement  grouting. 

In  Durax  paving,  the  setts  are  cubes  of  Swedish  granite,  but 
they  are  small  (about  2-inch  cubes),  with  plain  facets,  and  are 
laid  in  regular  formations  in  asphaltic  composition,  the  result 
being  a  very  durable  and  not  very  noisy  road,  as  it  is  compara- 
tively smooth  on  the  surface. 

Wood  paving  is  the  most  expensive,  but  possesses  the  follow- 
ing advantages: — It  is  comparatively  noiseless;  it  is  clean,  and 
creates  no  mud  of  itself  until  it  is  worn;  cleansing  is  easy,  when 
not  nmch  worn;  and,  though  slippery  at  times,  a  fall  does  not 
hurt  a  horse  like  a  fall  on  an  asphalt  or  macadam  road.  The  dis- 
advantage is  its  capacity  for  absorption,  with  the  giving  off  of 
offensive  odours  during  the  hot,  dry  season ;  but  this  is  in  some 


SOILS    AND    BUII.DINT,    SITES  273 

measure  obviated  by  the  use  of  hard  woods,  crcosoted  under 
pressure  and  jointed  with  impervious  material. 

Asphalt  is  the  most  sanitary  paving,  being  smooth,  imper- 
meable, jointless  and  most  durable.  It  is  cleansed,  swept,  and 
flushed  more  easily  than  any  other  kind  of  paving,  and  is  ad- 
mirably adapted  for  all  classes  of  town  roads  and  streets  which 
are  level,  or  have  only  very  slight  gradients.  Its  chief  dis- 
advantage is  that  it  is  slippery  when  tirst  damped  with  rain,  and 
that  horses  fall  very  heavily  on  it.  It  is  doubtful,  however,  if 
it  is  more  slippery  than  wood  under  similar  circumstances.  For 
motor  traffic  and  for  pedestrians  asphalt  forms  an  ideal  pavmg 
material. 

For  the  surface  treatment  of  roads  for  the  purpose  of  dust 
laying,  the  methods  which  are  employed  are  watering,  tarring, 
oil  tarring,  and  treatment  with  certain  trade  preparations  con- 
taining tar  oils,  etc.,  and  calcium  chloride.  It  is  generally 
accepted  that  coal  tar  should  be  apphed  hot,  and  the  treated 
surface  covered  at  once  with  fine  grit.  Oil-tar  is  the  by-product 
of  the  manufacture  of  gas  from  oil,  and  it  is  necessary  to  apply 
about  four  dressings  during  the  six  summer  months.  It  may  be 
applied  by  means  of  the  ordinary  water-cart,  manual  labour 
being  utihzed  to  work  it  into  the  road.  A  solution  of  calcium 
chloride  may  be  apphed  by  means  of  the  ordinary  water-cart, 
the  calcium  chloride,  by  taking  up  moisture  from  the  atmosphere, 
tending  to  keep  the  road  surface  slightly  moist. 

The  Dwelling — General  Considerations 

With  regard  to  aspect  in  this  country,  north  and  north-eastern 

aspects  are  cold,  whilst  southern  are  warm;  north-western  and 

south-western  are  exposed  to  boisterous  winds,  and  the  latter 

generally  to  driving  rains;  the  south-easterly  aspect  is  generally 

dry  and  mild,  and  it  is  well  to  select  this  for  the  living  rooms  of 

a  house.     Sunshine  should  be  capable  of  entering  every  living 

room  at  some  period  of  the  day.     The  provision  of  bay  windows 

will  help  to  secure  this  desideratum.     The  sufficient  lighting  of 

every  room  is  most  important.     Gwilt's  rule  that  there  should  be 

I  square  foot  of  glass  to  every  100  cubic  feet  of  room-space  is 

probably  rather  an  under-estimate  of  the  requirement  in  towns; 

on  the  other  hand,  excessive  window  provision  makes  a  room  very 

warm  in  summer  and  cold  in  winter. 

18 


274  HYGIENE    AND    PUBLIC    HEALTH 

All  staircases,  passages,  and  corridors  should  be  well  lighted 
and  ventilated  direct  from  the  outside  air. 

Bedrooms  should  have,  where  practicable,  an  east  or  south- 
east aspect,  so  as  to  get  the  morning  sun;  they  should  have 
plenty  of  window  area  and  an  open  fire-place. 

Too  little  attention  is  often  given  to  the  situation  of  the  larder, 
and  it  is  frequently  found  in  a  most  undesirable  position — badly 
lighted,  badly  ventilated,  the  window  opening  just  above  the 
dust  bin,  and  one  lath  and  plaster  wall  separating  it  from  a 
water-closet.  The  larder  should  face  north  for  coolness,  and 
have  provision  for  a  through  current  of  fresh,  pure  air;  the 
window  should  be  protected  with  perforated  zinc  to  exclude 
insects. 

All  chimneys  should  be  kept  as  much  as  possible  together, 
and  protected  from  cold  so  as  to  favour  upward  draught. 

The  most  sanitary  wall  covering  for  water-closets,  bathrooms 
and  sculleries  is  glazed  tiles,  or  the  walls  may  be  cemented 
and  painted;  in  either  case  they  can  be  easily  and  frequently 
cleansed.  For  bedrooms  distempering  is  to  be  preferred  to  wall- 
paper. If  in  the  sitting-rooms  wall-paper  is  employed,  one  with 
a  smooth  varnished  surface  should  be  chosen  in  preference  to  an 
uncleanly,  absorbent  flock  paper. 

As  to  the  floors,  the  ordinary  floor  boarding  supported  on 
floor  joists,  placed  i  foot  apart,  and  leaving  an  open  space  some 
inches  in  depth  between  the  floor  surface  and  the  concrete  founda- 
tion or  the  ceiling  of  the  room  below,  has  little  to  recommend  it. 
The  space  beneath  the  floor  becomes  a  receptacle  for  dirt,  which 
gets  through  the  cracks  between  the  floor  boards.  Whenever 
such  a  floor  is  laid  down  it  should  be  made  with  grooved  and 
tongued,  or  ploughed  and  tongued  boarding,  so  as  to  insure  the 
boards  being  tight-fitting.  But  it  is  far  preferable  that  "  sohd 
floors  "  should  be  constructed  by  laying  the  floor  joists  side  by 
side  and  nailing  the  floor  boarding  to  the  solid  upper  surface  of 
the  joists. 

For  large  buildings  fire-proof  flooring  formed  of  coke-breeze 
and  cement  laid  on  steel  joists  is  most  desirable.  The  floor 
boards  should  be  nailed  to  the  fire-proof  material. 

Glazed  tiles  and  bricks  form  satisfactory  floors  for  water-closets, 
lavatories,  bathrooms,  sculleries,  and  larders.  The  best  floor 
covering  for  the  rest  of  the  house  is  hard  wood,  such  as  oak  well 
fitted,  beeswaxed,  and  polished;   or  hard,  well  seasoned  deal. 


SOILS    AND    BUILDING    SITES  275 

stained  and  well  varnished.     Parquet  flooring  insures  a  uniform 
and  impervious  surface. 

For  roofing,  some  non-absorbent  material  is  to  be  preferred. 
Roofs  of  thatch  and  wood  are  liable  to  be  damp  and  to  harbour 
insects,  and  their  inflammability  is  a  source  of  danger.  Slates 
and  tiles  are  good  materials;  the  former  are  light,  but,  being 
good  conductors  of  heat,  are  cold  in  winter  and  hot  in  summer, 
whereas  the  latter,  though  heavy,  are  warmer  in  winter  and 
cooler  in  summer.  Lead,  zinc,  and  copper  have  all  been  used 
for  roofing;  like  slates,  they  are  good  conductors  of  heat,  and 
impervious. 

In  house  furnishing,  woolly  and  fluffy  articles  of  decoration, 
heavy  draperies,  fittings  and  ornaments,  which  will  harbour 
dust  and  render  it  difficult  of  removal,  should  be  avoided;  and 
carpets  should  not  be  made  to  cover  the  whole  floor  and  be  nailed 
to  it,  but  should  be  laid  down  as  squares  which  admit  of  easy 
removal  for  cleansing  purposes. 

Walls  are  generally  built  of  brick,  stone,  timber,  or  concrete. 
The  materials  used  in  building  should  be  as  compact  and  as  im- 
permeable as  possible;  all  bricks  should  be  hard  and  as  httle 
absorbent  of  moisture  as  practicable,  all  wood  well  seasoned,  and 
the  plaster  impermeable. 

"  Light  construction  "  materials  are  now  being  extensively 
used  for  certain  classes  of  building,  and  especially  for  structures 
designed  for  temporary  occupation.  The  weight  of  the  building 
is  carried  on  steel  piers  and  steel  framing,  the  interspaces  being 
filled  with  hollow  slabs  of  stoneware  material,  which  form  a 
wall  at  once  impervious  to  moisture  and  highly  non-conductive. 
The  cost  of  such  a  structure  is  considerably  less  than  if  it  was 
brick-built.  Buildings  constructed  of  "  reinforced  concrete  " — 
i.e.,  concrete  strengthened  by  steel  rods  and  ties  introduced  in 
its  substance — are  also  strong  and  cheap.  A  notable  example 
of  this  form  of  construction  may  be  seen  in  the  new  General 
Post-office  at  St.  Martin's-lc-Grand,  London. 


CHAPTER  VI 
CLIMATE  AND  METEOROLOGY 

Climate. 

The  human  body  possesses  marvellous  powers  of  adaptability 
to  the  varying  external  conditions  occasioned  by  changes  of 
climate  and  season,  and  the  transition  from  cold  to  heat,  dryness 
to  humidity,  and  vice  versa.  The  normal  temperature  of  the 
body  is  sustained,  and  the  bodily  functions  are  properly  per- 
formed, under  all  the  varying  conditions  of  climate  and  season 
to  be  met  with  in  the  habitable  globe. 

In  hot  cHmates,  where  the  temperature  of  the  air  approaches, 
or  even  exceeds  at  times,  the  temperature  of  the  blood,  there 
is  little  call  made  upon  the  heat-producing  powers  of  the  bod3^ 
As  less  food  is  required,  metabolism  is  decreased ;  the  urea  of  the 
urine  and  the  respiratory  carbonic  acid  are  lessened  in  amount; 
the  digestive  and  assimilative  powers  are  lessened;  and  oxygena- 
tion of  the  blood  is  diminished,  because  the  number  of  respira- 
tions is  decreased  and  the  heated  air  contains  less  oxygen  in  a 
cubic  foot  than  cold  air.  At  the  same  time  great  heat,  although 
compatible  with  health,  is  enervating;  for  the  perfection  of 
bodily  activity  can  only  be  obtained  when  tissue  changes  are 
rapid.  In  hot  climates  the  skin  is  extremely  active,  and  the 
secretion  of  sweat  enormously  increased.  This  means  great 
evaporation  from  the  surface  and  cooling  of  the  blood,  with  the 
result  that  the  body  temperature  is  maintained  at  its  normal 
level. 

At  high  atmospheric  temperatures  the  body  loses  little  or  no 
heat  by  radiation,  while  the  loss  by  evaporation  is  considerable; 
whereas  at  low  atmospheric  temperatures,  while  the  heat  loss 
by  radiation  is  considerable,  that  lost  by  evaporation  is  very 
small  indeed. 

The  effects  of  cold  are  exactly  the  reverse  to  those  of  heat. 

276 


CLIMATE    AND   METEOROLOGY  277 

To  maintain  the  temperature  of  the  body,  tissue  metamorphosis 
must  be  rapid;  food,  and  especially  carbonaceous  food,  must 
be  taken  in  hirge  quantities;  oxygenation  of  the  blood  and 
ehmination  of  COg  are  increased;  the  skin  functions  are  reduced 
to  a  minimum,  while  the  excretion  of  urine  increases,  and  but 
little  blood  reaching  the  surface,  surface  cooHng  is  obviated; 
whilst  the  rapid  tissue  changes  permit  of  great  bodily  and  mental 
activity  being  shown. 

Great  humidity  of  the  air  causes  lessened  evaporation  from 
the  lungs  and  skin.  For  the  air,  being  saturated,  or  nearly  so, 
with  moisture,  has  little  drying  power,  and  the  moisture  from 
the  skin  and  lungs  is  with  difficulty  evaporated.  The  evapora- 
tion of  moisture,  by  which  much  heat  is  rendered  latent,  is  one 
of  the  chief  means  of  cooling  the  body.  Consequently,  when 
the  air  is  hot  and  very  moist,  the  humidity  tends  to  increase  the 
effects  of  the  heat;  the  blood  is  with  chfficulty  kept  at  its  proper 
temperature;  and  all  the  disagreeable  results  of  the  high  tempera- 
ture are  intensified.  Moreover,  the  humidity  of  the  air  affects 
the  climate  of  a  place  by  hindering  the  terrestrial  radiation  of 
heat. 

For  healthy  people  in  temperate  climates,  the  pleasantest 
degree  of  humidity  is  about  75  per  cent,  of  saturation.  This 
figure  is  a  climatic  average  for  the  year.  The  relative  humidity 
of  the  outer  air  varies  greatly  from  season  to  season,  from  day 
to  day,  and  even  from  hour  to  hour,  and  there  is  no  evidence 
that  atmospheres  of  high  or  low  relative  humidity  are  per  se 
unhealthy.  At  night  and  during  rain  the  relative  humidity  is 
high,  the  atmosphere  being  often  nearly  or  quite  saturated  with 
watery  vapour,  whilst  a  warm  sun  and  a  dry  wind  will  cause  a 
drop  in  the  relative  humidity  from  90  to  40,  and  that  within  the 
space  of  an  hour  or  two.  It  is  evident  that,  in  Nature,  the  changes 
in  relative  humidity  are  extensive  and  rapid;  and  it  seems  prob- 
able that  the  human  body,  under  normal  conditions  of  health, 
is  capable  of  adapting  itself  as  readily  to  these  hygromctric 
changes  as  it  is  to  the  varying  temperatures  of  an  uncertain  and 
variable  climate.  Some  of  the  more  rapid  fluctuations  of  rela- 
tive humidity  are  probably  attributable  to  passing  intervals  of 
sunshine. 

The  effect  of  movement  of  air  (winds)  on  evaporation  is  very 
great.  In  cold  weather  a  chilly  wind,  if  dry,  increases  the 
evaporation,  and  also  lowers  the  temperature  of  the  body  by 


278  HYGIENE   AND    PUBLIC   HEALTH 

the  impact  of  its  cold  particles,  which  absorb  the  heat  of  the 
body  and  then  pass  away  to  be  replaced  by  more  cold  air.  The 
skin  becomes  dry  and  chapped,  and  the  lungs  are  irritated.  In 
hot  climates  a  dry,  hot  wind  increases  the  evaporation  enor- 
mously. 

The  warm  and  moist  south-west  winds  in  the  British  Isles 
are  mild  and  relaxing,  while  the  drier  and  colder  east  and  north 
winds  are  bracing. 

At  high  altitudes  the  air  is  rarefied,  and  the  pressure  of  the 
atmosphere  is  diminished.  The  other  conditions  met  with  in 
mountain  climates,  as  contrasted  with  those  of  plains,  are: 
(i)  Greater  movement  of  air — strong  winds  are  very  prevalent; 
(2)  lessened  humidity;  (3)  increased  sunhght;  (4)  great  freedom 
of  the  air  from  suspended  matter — mineral  and  organic;  (5)  a 
larger  amount  of  ozone  in  the  air;  (6)  a  lowered  temperature 
generally;  but  as  the  soil  is  rapidly  heated  by  the  sun,  the  days 
in  summer  may  be  warm,  whilst  the  rapid  radiation  of  heat,  as 
soon  as  the  sun  sets,  causes  sudden  cooling  and  a  very  low 
temperature  at  night.  Temperature  decreases  with  altitude  to 
the  extent  of  about  1°  F.  to  every  300  feet  of  ascent. 

Although  the  weight  of  oxygen  in  a  cubic  foot  of  air  is  decreased 
at  high  altitudes,-^  the  oxygenation  of  the  blood  is  increased,  for 
the  respirations  are  more  frequent  and  have  greater  depth; 
and  after  a  period  of  residence  the  capacity  of  the  chest  is  found 
to  be  increased  in  all  its  measurements,  together  with  increased 
power  of  expansion  and  contraction.  The  action  of  the  heart 
is  also  increased,  and  tissue  change  is  stimulated  by  the  low 
temperature  and  the  dryness  of  the  air,  leading  to  improved  diges- 
tion, assimilation  and  excretion,  with  increased  bodily  activity. 

These  effects  of  residence  at  a  high  altitude,  together  with  the 

freedom  of  the  air  from  dust  and  germs,  and  its  impregnation 

with  ozone,  have  led  to  the  treatment  of  cases  of  phthisis  at 

mountain  resorts,  with  often  the  most  beneficial  results.     The 

cases  most  benefited  are  those  in  an  early  stage  without  much 

congestion   or  bronchitis,   which  might  be  aggravated  by  the 

cold  dry  air.     It  is  advisable  that  spots  should  be  chosen  wliich 

are  sheltered  from  cold  winds;  and  those  popular  resorts,  ^^'hcrc 

many  phthisical  persons  are  crowded   together  in   hotels  and 

1  The  weight  of  oxygen  in  a  cubic  foot  of  air  is  diminished  in  proportion 
to  the  diminution  of  pressure ;  thus,  if  the  barometer  stands  at  20  inches, 
the  130-4  grains  of  oxygen  present  in  a  cubic  foot  of  dry  air  at  30  inches  of 
mercury  and  32°  F.    is  reduced  to  rj|[  of  130-4=  80-y  grains  only. 


CLIMATE  AXD  METEOROLOGY'  279 

boarding  houses  without  proper  precautions  being  taken,  should 
be  avoided.  As  much  time  as  possible  should  be  spent  in  the 
open  air. 

A  mountainous  district  in  proximity  to  the  sea  is  Hable  to 
excessive  rainfall.  The  moist  currents  of  air  blowing  in  from  the 
sea  are  chilled  by  striking  against  the  mountain  chain;  clouds 
are  formed,  and  some  of  the  moisture,  no  longer  able  to  be  held 
as  invisible  vapour  at  the  lower  temperature,  is  deposited  as 
rain,  snow,  or  sleet,  according  to  the  temperature  and  season  of 
the  year.  If  the  mountains  are  in  the  centre  of  a  continent  far 
removed  from  the  sea,  the  rainfall  may  not  be  great.  The  excess 
of  moisture  in  the  ocean  currents  will  already  have  been  deposited 
before  reaching  the  hills;  and  in  these  situations  a  mountain 
chmate  without  the  drawback  of  excessive  rainfall  may  be 
obtained,  suitable  for  the  requirements  of  consumptives  and 
invahds.  The  westerly  winds  which  blow  over  the  Rocky 
Mountains  deposit  most  of  their  moisture  on  the  western  sides  of 
the  range,  and  on  the  eastern  slopes  the  climate  is  comparatively 
dry  and  cold. 

Increased  pressure  of  the  atmosphere  produces  effects  very 
much  of  an  opposite  ,nature  to  those  just  considered.  It  is 
found,  however,  that  the  system  quickly  accustoms  itself  to 
increased  atmospheric  pressure,  and  that  men  can  work  vigor- 
ously in  diving  bells,  and  in  the  very  deepest  mines. 

In  the  compressed  air  chambers  necessary  to  lay  the  founda- 
tions of  bridges  and  aqueducts  under  water,  the  painful  effects 
of  exposure  to  very  high  atmospheric  pressures  are  generally 
referred  to  as  "  caisson  disease."  A  caisson  is  a  cyhnder 
of  iron  plates  riveted  together,  which  is  sunk  on  the  bed  of  a 
river  so  as  to  form  a  shaft.  Into  this,  when  closed  at  the  top, 
air  is  pumped  under  sufficient  pressure  to  force  the  water  out 
of  the  lower  part  of  the  shaft,  and  to  keep  it  out  while  men 
excavate  the  bed  of  the  river,  for  the  purpose  of  obtaining  a 
suitable  foundation  for  the  piers  of  bridges.  There  is  at  the 
top  part  of  the  cylinder,  near  to  the  closing  diaphragm,  a 
chamber  or  "  air  lock,"  in  which  the  pressure  of  the  air  can  be 
gradually  increased  or  diminished.  By  this  means  the  men, 
before  entering  the  compressed  air  in  the  shaft,  are  subjected 
to  a  pressure  which  equals  that  within  the  shaft.  On  leaving  the 
shaft  the  men  are  gradually  "  decompressed  "  in  this  lock  before 
emerging  into  the  outside  air. 


280  HYGIENE    AND    PUBLIC   HEALTH 

The  workers  are  liable  to  suffer  from  the  altered  conditions  of 
atmospheric  pressure  to  which  they  are  daily  subjected,  and  they 
are  affected  far  more  by  the  consequences  of  decompression  and 
returning  to  the  outside  air,  than  from  compression  and  con- 
tinuance of  exposure  to  the  high  pressure  in  the  caisson. 

The  leading  symptoms  of  caisson  disease  are  :  (i)  Unpleasant 
sensations  or  severe  pains  in  the  ears,  doubtless  the  result  of  the 
tympanum  being  driven  in  by  the  compressed  air.  The  drum 
of  the  ear  is  said  to  have  been  even  ruptured,  and  sometimes 
deafness  results.  These  ear  symptoms  are  materially  aggravated 
if  the  person  happens  to  be  suffering  from  a  cold  in  the  head 
or  sore  throat,  when  pain  in  the  forehead  is  often  marked. 
(2)  Neuro-muscular  pains.  (3)  A  feeling  of  giddiness,  with  a 
tendency  to  fall.  (4)  Loss  of  power  in  the  legs,  amounting  at 
times  to  paralysis.  (5)  SHght  to  severe  pains  in  legs,  arms,  and 
shoulders.  (6)  Epistaxis.  (7)  Itching  of  skin.  (8)  Haemoptysis, 
(g)  Epigastric  pain,  and  sometimes  nausea  and  vomiting. 
(10)  Occasionally  unconsciousness.  There  is,  of  course,  a 
physiological  rise  in  the  blood  pressure. 

Three  theories  have  been  adduced  to  explain  compressed  air 
illness.  It  has  been  held  to  be  due  to  COg  poisoning;  to  the 
mechanical  congestion  of  internal  organs;  and  to  increased 
solution  by  the  blood  of  the  nitrogen  in  the  compressed  air,  and 
the  liberation  of  this  gas  (probably  forming  gas  emboli)  during 
decompression.  The  last  theory  is  most  generally  accepted.  If 
the  first  were  correct,  the  illness  should  occur  while  the  men  are 
in  the  caisson,  and  not  after  they  emerge  from  it.  In  support  of 
the  second  theory,  it  may  be  said  that  in  several  necropsies 
the  membranes  of  the  brain,  etc.,  have  been  found  deeply 
congested. 

The  symptoms  mostly  yield  to  recompression,  followed  by 
slow  decompression  lasting  some  forty-five  minutes. 

The  favouring  causes  are:  Too  long  stay  in  the  compressed  air; 
insufficient  ventilation  of  the  compressed  air  space — the  amount 
of  illness  varies  inversely  with  the  extent  of  the  provision  for 
ventilation  (Sncll) ;  too  rapid  decompression;  fulness  of  habit; 
advancing  age;  over-indulgence  in  alcohol;  and  organic  disease. 
New  hands  suffer  more  than  the  old. 

The  preventive  measures  to  be  adopted  include:  Working 
during  short  shifts — if  the  pressure  exceeds  35  pounds,  the  shifts 
should  probably  not  exceed  four  liouis,  and  if  the  pressure  reaches 


CLIMATE  AND  METEOROLOGY  28l 

50  pounds,  two  hours;  an  abundant  supply  of  fresh  air;  electric 
lighting  to  be  employed,  so  as  to  insure  the  continued  purity  of 
the  air;  the  rate  of  decompression  certainly  not  to  exceed  one 
niinuie  to  every  5  pounds  of  pressure;  the  systematic  examination 
of  all  hands,  and  the  selection  of  those  who  are  physically  sound; 
advice  to  be  given  as  to  how  to  inflate  the  middle  ear  by  swallow- 
ing air  when  uneasiness  first  appears;  as  to  the  importance  of 
rest  for  a  short  period  after  leaving  the  compressed  air;  and  as 
to  the  necessity  for  extreme  temperance  with  alcohol.  It  is 
desirable  to  temporarily  exclude  those  with  a  cold  in  the  head  or 
sore  throat. 

The  climate  of  small  islands  and  of  places  on  the  seashore  differs 
from  that  of  the  interior  of  continents  chiefly  in  its  greater 
equability.  The  variations  in  temperature  between  day  and 
night  and  between  summer  and  winter  are  much  less  marked, 
whilst  the  winds  blowing  in  from  the  sea  bring  a  moist  but  pure 
air,  comparatively  rich  in  ozone  and  free  from  dust  and  germs. 
The  specific  heat  of  water  is  far  greater  than  that  of  land ;  hence 
water  heats  slowly,  and  parts  with  its  heat  slowly.  The  land 
heats  quickly  and  radiates  quickly;  but  on  the  land  it  is  the 
surface  alone  which  is  affected  by  the  change  of  seasons.  At 
Greenwich  the  variations  between  summer  and  winter  tempera- 
tures at  a  depth  of  25  feet  are  only  about  2°  F.  In  winter  the 
ocean  acts  as  a  storehouse  for  the  heat  absorbed  from  the  summer 
sun,  and  slowly  parts  with  it  to  warm  the  superincumbent  air. 
In  summer  the  land  is  heated  by  the  sun  more  rapidly  than  the 
water;  consequently,  the  air  over  the  land  is  heated  and  rises, 
and  a  cool  breeze  blows  in  from  the  sea  during  the  day.  During 
the  night  the  earth  is  rapidly  cooled  by  radiation,  if  the  sky  is 
clear ;  the  air  over  the  sea  is  then  warmer  than  the  air  over  the 
land,  it  rises,  and  a  land  breeze  sets  out  to  sea.  On  a  summer's 
day  at  the  seashore  the  air  is  constantly  in  motion,  and  is  cool  and 
moist,  whilst  in  the  interior  it  may  be  insufferably  hot,  close  and 
dry.  Marshes,  by  the  evaporation  from  the  shallow  water,  help 
to  lower  the  summer  temperature;  but  the  influence  of  large 
lakes,  as  in  North  America,  is  to  bring  about  an  almost  insular 
climate  in  simimer,-and  a  continental  one  in  winter,  for  the  frozen 
lakes  then  exert  a  similar  influence  to  land. 

Ocean  climates  are  of  the  greatest  benefit  to  certain  cases  of 
lung  disease,  where  a  pure  air,  free  from  dust,  but  moist  and  of 
equable  temperature  is  desired;  but  ocean  voyages  should  be 


282  HYGIENE    AND    PUBLIC   HEALTH 

recommended  with  extreme  caution  to  phthisical  patients.  The 
confinement  and  over-crowding  in  cabins  and  state  rooms,  the 
want  of  exercise,  and  the  costive  habit  thus  produced  (tending 
to  excite  haemoptysis),  are  all  grave  disadvantages,  and  may 
counteract  any  benefit  to  be  derived  from  the  sea  air. 

The  effect  of  vegetation  on  climate  must  not  be  lost  sight  of. 
In  cold  climates  trees  and  shrubs  obstruct  the  passage  of  the 
sun's  rays  to  the  soil,  which  is  therefore  liable  to  be  cold  and 
moist;  on  the  other  hand,  they  may  protect  against  cold  winds. 
In  hot  climates  the  evaporation  of  water  from  the  leaves  tends 
to  dry  the  soil  and  to  lower  the  temperature,  and  the  ground 
is  sheltered  from  the  direct  rays  of  the  sun  and  kept  cool.  Thus, 
the  heat  of  summer  is  lowered  and  the  cold  of  winter  tempered 
by  the  presence  of  trees,  and,  having  a  lower  temperature  than 
the  neighbouring  earth's  surface,  high  forests  increase  the  rain- 
fall. In  very  dense  forests  the  air  is  generally  stagnant.  Prob- 
ably in  all  climates  a  due  admixture  of  herbage,  shrubs  and 
trees,  without  dense  undergrowth,  but  admitting  the  passage 
of  free  currents  of  air  in  every  direction,  is  the  most  conducive 
to  health.  Large  tracts  of  country  destitute  of  trees  and  vegeta- 
tion are  in  hot  climates  unbearably  warm  and  dry,  and  in  cold 
climates  are  exposed  to  every  chilHng  wind.  In  such  districts, 
too,  rainfall  is  often  absent  or  very  slight  in  amount,  the  influence 
exerted  by  trees  upon  water-charged  clouds  being  wanting. 
For  these  reasons  the  desert  of  Sahara  gives  to  the  south 
of  Europe  a  much  higher  temperature  than  would  otherwise  be 
the  case. 

The  mean  temperature  of  the  air  of  any  place  is  dependent  on 
the  latitude,  the  altitude,  the  relative  proportions  of  land  and 
water,  the  aspect,  and  the  nature  of  the  soil;  and  the  extent  of 
the  diurnal  variations  in  temperature  is  largely  determined  by  the 
proximity  to  the  coast  and  the  height  above  sea  level.  The 
"amplitude  of  the  yearly  fluctuations"  in  temperature  is  not 
more  than  about  4°  F.  in  some  tropical  places  at  sea  level,  while 
it  may  be  as  much  as  110°  F.,  or  even  more,  in  the  heart  of  large 
continents  situated  near  the  poles. 

The  principal  factors,  therefore,  which  determine  the  climate 
of  a  district  are:  (1)  Distance  from  the  equator;  (2)  distance 
from  the  sea;  (3)  altitude;  and  (4)  prevailing  winds. 

Of  the  many  separate  elements  that  go  to  make  up  the  climate 
of  a  place,  temperature  is  the  most  important,  and  the  mean 


CLIMATE    AND    METEOROLOGY  283 

annual  temperature  depends  primarily  upon  the  amount  of 
radiant  heat  received  from  the  sun.  The  heat  received  from 
the  sun,  however,  in  one  place  may  be  carried  by  winds  and 
ocean  currents  to  another.  The  mean  temperature  of  the 
tropics  is  about  80"  F.,  and  that  of  the  arctic  circle  in  latitude 
60°  is  25°  F.,  the  difference  of  some  55°  F.  being  due  to  the  fact 
that  the  heat  received  from  the  sun  is  concentrated  upon  a  small 
surface  when  the  sun's  rays  fall  near  the  equator,  and  is  spread 
over  a  large  surface  when  they  fall  near  the  poles.  The  differ- 
ence would  be  far  greater  were  it  not  for  the  heat  carried  away 
from  the  tropics  to  the  temperate  and  arctic  regions  by  ocean 
currents,  and  to  a  less  extent  by  winds. 

The  difference  between  summer  and  winter  temperatures  is 
also  important,  but  little  variation  being  shown  in  places  within 
the  tropics,  or  on  islands  in  the  middle  of  large  oceans,  either  in 
tropical  or  temperate  latitudes. 

The  heating  of  the  air  in  the  tropics,  the  coohng  around  the 
poles,  and  the  deflective  action  of  the  earth's  rotation,  produce 
all  the  prevaiHng  winds  of  the  globe.  The  colder  air  of  the 
northern  and  southern  regions  of  the  globe  is  constantly  flowing 
towards  the  warmer  and  more  rarefied  air  over  the  open  seas  on 
both  sides  of  the  equator.  The  result  of  the  earth's  rotation 
on  the  flow  of  the  warm  water  from  the  equator  towards  the 
poles  in  the  North  Atlantic  Ocean  is  the  large  circular  swirl, 
the  northern  and  eastern  sides  of  which  produce  the  well-known 
current  of  the  Gulf  Stream.  This  current,  together  with  the 
circumstance  that  the  prevailing  winds  have  a  westerly  direction, 
accounts  for  the  British  Isles  possessing  such  a  mild  climate; 
whilst  countries  with  the  same  latitude  as  England — such  as 
Labrador  and  Eastern  Asia,  in  which  the  prevailing  winds  are 
from  the  land  instead  of  from  the  sea — have  a  mean  winter 
temperature  below  zero. 

Weather  Observations. 
Under  the  modern  system,  a  number  of  barometrical  readings 
taken  at  the  same  time  over  an  extended  area,  such  as  the 
greater  part  of  Western  Europe,  are  telegraphed  to  a  central 
station,  where  they  are  laid  down  upon  a  map.  On  this  map 
lines  are  drawn  connecting  the  places  showing  equal  barometrical 
pressure;  these  lines  are  termed  "  isobars."  This  weather  map 
will  show  the  cyclonic  or  anticyclonic  systems,  as  the  case  may 


284  HYGIENE    AND    PUBLIC    HEALTH 

be,  their  position,  and  their  extent.  A  cyclonic  system  is  a 
system  liaving  at  its  centre  the  lowest  barometrical  pressure,  and 
surrounded  by  isobars  of  gradually  increasing  pressure.  The 
isobars  will  be  near  or  far  apart  according  to  the  amount  of 
depri?ssion  in  the  centre.  If  this  depression  is  great,  then  the 
isobars  are  generally  close  together,  and  the  "  gradients  "  are 
said  to  be  "  steep."  If,  on  the  other  hand,  the  depression  in 
the  centre  is  shallow,  the  isobars  are  further  apart,  and  the 
gradients  are  "  shallow." 

An  anticyclonic  system  is  the  reverse  of  this,  for  its  centre 
is  the  highest  barometrical  reading,  and  it  is  surrounded  by 
isobars  of  gradually  decreasing  pressure. 

In  order  to  restore  atmospheric  equilibrium,  the  air  tends  to 
move  from  a  region  where  the  barometer  is  high  and  pressure 
greatest,  towards  one  where  it  is  low  and  the  pressure  is  least. 
Consequently,  currents  of  air  set  in  from  all  sides  towards  the 
centre  of  a  cyclonic  system,  and  flow  out  in  all  directions  from 
the  centre  of  an  anticyclonic  system.  These  currents  of  air  do 
not,  however,  as  a  matter  of  fact,  flow  straight  to  or  from  the 
centre,  but  have  a  gyratory  movement  imparted  to  them,  owing 
to  the  rotation  of  the  earth  on  its  own  axis. 

The  equatorial  circumference  of  the  earth  being  24,900  miles, 
and  the  earth  rotating  on  its  axis  once  in  twenty-four  hours, 
it  follows  that  a  point  on  the  earth's  crust  at  the  equator  must 
be  carried  round  at  the  rate  of  1,040  miles  an  hour.  In  latitude 
30°,  however,  the  point  would  only  move  at  the  rate  of  900  miles 
an  hour,  owing  to  the  lesser  circumference  of  the  earth  at  this 
distance  from  the  equator.  In  latitude  60°  the  rate  will  be  only 
520  miles  an  hour,  and  at  the  poles  it  will  be  nil.  Now,  the 
atmosphere  is  carried  round,  from  west  to  east,  at  the  same  rate 
as  the  earth's  crust;  consequently  winds  or  currents  of  air 
travelling  from  the  equator  towards  the  poles,  or  from  low  lati- 
tudes into  high,  tend  to  keep  the  higher  rate  of  rotary  motion 
imparted  to  them  when  nearer  the  equator,  and  become  westerly 
— that  is,  come  from  the  south-west  (in  the  northern  hemi- 
sphere) as  they  progress  towards  high  latitudes.  In  the  same 
way,  winds  travelling  from  high  latitudes  to  low  ones  meet  an 
atmosphere  which  is  rotating  at  a  greater  rate  than  they  are, 
and  consequently  appear^  to  come  out  of  the  north-east  (in  the 

^  As  when  a  steamship  is  rapidly  passing  through  the  air  from  west  to 
east  a  wind  coming  from  the  north  appears  to  come  from  the  north-cast. 


CLIMATE    AND    METEOROLOGY 


285 


northern  hemisphere).  This  is  the  reason  why  the  trade  winds 
wliich  blow  towards  the  equator  appear  as  north-east  winds 
in  the  northern  hemisphere,  and  south-east  winds  in  the  southern 
hemisphere.  This  direction  of  the  trade  winds  is  constant  over 
all  open  seas  to  about  30°  north  and  south  of  the  equator,  but 
land  changes  their  course.  The  position  of  the  sun  has  an  in- 
fluence on  the  strength  and  direction  of  these  trade  winds; 
when  the  sun  is  near 
the  Tropic  of  Cancer 
the  south-east  wind  is 
more  southerly  and 
strong,  and  the  north- 
east wind  is  weaker 
and  more  easterly;  and 
the  reverse  happens 
when  the  sun  ap- 
proaches the  Tropic 
of  Capricorn. 

The  same  forces 
apply  to  the  currents 
of  air  moving  towards 
the  centre  of  a  cyclonic 
system,  or  away  from 
the  centre  of  an  anti- 
cyclonic  system.  In 
the  case  of  a  cyclonic 
system  (in  the  northern 
hemisphere),  a  current 
setting  towards  its 
centre  from  the  north 
appears  to  come  from 
north-east.  A  current 
setting  towards  the 
centre  from  the  south 

of  the  system  is  deflected  to  the  east,  or  comes  from  south-west. 
In  this  way  a  gyratory  or  spiral  movement  is  imparted,  which 
causes  the  wind  to  tr .  vel  round  the  centre  of  a  cyclonic  depres- 
sion, in  a  direction  against  the  hands  of  a  watch;  or  supposing 
a  person  to  be  travelling  with  his  face  towards  the  direction  the 
wind  is  taking,  he  will  always  keep  the  centre  of  the  system, 
i.e.,  the  point  of  lowest  pressure,  on  his  left  hand  side. 


Fig.    39.  —  Synoptic  Chart  showing 
Cyclonic  System. 

The  arrows  show  the  direction  of  the  wind. 
The  figures  show  the  barometric  pressure 
of  the  isobars. 


286 


HYGIENE    AND    PUBLIC   HEALTH 


The  central  space  of  the  cyclone  is  occupied  by  a  vast  ascending 
current,  which  after  rising  to  a  considerable  height  flows  away 
as  upper  currents  into  surrounding  regions. 

The  direction  of  the  wind  round  an  anticyclonic  centre  is 
exactly  the  reverse.  The  air  flows  away  from  the  centre  of 
greatest  pressure  in  all  directions.  The  current  flowing  south- 
wards is  deflected  to  the  west,  and  appears  to  come  from  north- 
east.    The  current  flowing  northward  is  deflected  to  the  east, 

and  comes  from  south- 
west. Consequently 
the  currents  revolve 
in'ith  the  hands  of  a 
watch,  and  the  person 
travelling  with  the 
wind  keeps  the  centre 
of  the  system  —  the 
point  of  highest  pres- 
sure— always  on  the 
right  hand. 

From  this  it  follows 
that  having  a  weather 
(synoptic)  chart  before 
us,  and  knowing  the 
distribution  of  pressure 
over  the  area  included 
in  the  chart,  we  can 
generally  tell  the  direc- 
tion of  the  wind  at  any 
particular  spot;  and  if 
we  know  what  course 
the  system  is  taking, 
i.e.,  the  direction  in 
which  it  is  travelling,  we  can  predict  what  changes  will  sub- 
sequently take  place  in  that  direction,  so  long  as  it  remains 
included  in  the  system. 

Cyclonic  systems  are  never  stationary.  They  move  over  the 
earth's  surface,  usually  from  west  to  east  in  European  latitudes; 
but  in  the  case  of  the  British  Isles,  coming  from  off  the  Atlantic, 
their  approach  is  difficult  to  forecast.  In  these  depressions  the 
isobars  lie  close  together  and  the  winds  are  strong.  The  greater 
the  depression  in  the  centre  and  the  steeper  the  gradient,  the 


Fig.  40.- 


-Synoptic  Chart  showing  Anti- 
cyclonic  System. 


CLIMATE    AND   METEOROLOGY  287 

more  violent  is  the  wind;  but,  according  to  Scott,  no  simple 
relation  between  the  force  of  the  wind  and  the  steepness  of  the 
gradient  has  yet  been  determined.  In  this  country  the  arrival 
of  cyclonic  systems  off  our  coasts  heralds  the  approach  of  cloudy 
skies,  wind,  rain,  and  damp  air.  These  conditions  imply  warmth 
in  winter,  and  cold  weather  in  summer.  The  centre  of  the 
cyclonic  depression  usually  lies  to  the  north  of  the  British  Isles; 
consequently,  these  islands  lying  in  the  track  of  the  southern 
portion  of  the  system,  the  wind  is  first  experienced  from  the 
south-east,  it  then  shifts  through  south  to  south-west,  and  blows 
harder  the  more  rapidly  the  mercury  drops.  When  the  barometer 
has  reached  its  lowest  point  the  wind  flies  round  to  west  or  west- 
north-west;  the  barometer  then  begins  to  rise,  the  rain  ceases, 
the  temperature  falls,  and  as  the  wind  becomes  north  the  sky 
clears,  and  fine  weather  is  again  experienced  (Scott). 

Anticyclones,  on  the  contrary,  are  generally  more  or  less 
stationary,  or  move  very  slowly.  The  isobars  lie  far  apart,  and 
the  winds  are  light.  They  are  accompanied  by  fine  weather, 
a  dry  atmosphere,  a  sky  generally  clear  of  clouds,  though  fogs 
are  very  likely  to  prevail  at  places.  These  conditions  produce 
cold,  frost,  or  fog  in  winter,  and  heat  in  suirmier. 

The  synoptic  charts  (figs.  39,  40)  show  that  the  wind  in  both 
cyclonic  and  anticyclonic  systems  has  a  direction  more  or  less 
parallel  to  the  isobars,  but  still,  on  the  whole,  tending  to  cross 
the  isobars  very  obliquely,  so  as  to  blow  spirally  towards  the 
centre  of  the  cyclone,  and  spirally  away  from  the  centre  of  the 
anticyclone. 

A  col  is  a  neck  of  relatively  low  pressure  connecting  two  anti- 
cyclones. It  is  comparable  to  the  col  which  forms  a  pass  between 
two  adjacent  mountain  peaks. 

Meteorological  Instruments. 

The  Barometer. — The  pressure  of  the  atmosphere  is  expressed 
by  means  of  a  barometer  in  terms  of  the  perpendicular  height 
of  a  column  of  mercury,  glycerine,  or  water,  which  it  is  capable 
of  supporting.  The  weight  of  the  atmosphere  at  the  sea  level 
supports  a  column  of  mercury  of  29-992  inches,  or  760  milli- 
metres, in  height,  a  column  of  glycerine  about  324  inches, 
and  one  of  water  34  feet,  in  height.  The  water  barometer 
is  accordingly  the  most  sensitive,  but  it  is  inconvenient 
in  use. 


288  HYGIENE    AND    PUBLIC    HEALTH 

The  simplest  form  of  mercurial  barometer  is  a  graduated 
U-tube,  with  one  end  closed.  The  closed  arm  is  about  32  inches 
in  height,  and  the  open  arm  about  8  or  9  inches.  The  mercury 
placed  in  the  U-tube  is  made  to  completely  occupy  the  closed 
arm,  so  that  all  the  air  is  displaced  from  it;  then,  when  the 
tube  is  brought  to  its  proper  upright  position,  and  the  mercury 
fails,  there  is  a  complete  vacuum  left  above  it  in  the  closed  arm. 
The  varying  pressure  of  the  atmosphere  on  the  surface  of  the 
mercury  exposed  in  the  open  (short)  arm  causes  the  level  of  the 
mercury  to  rise  and  fall  in  the  long  (closed)  arm;  and  the 
difference  between  the  levels  in  the  two  arms  represents 
the  height  of  the  column  of  mercury  supported  by  the 
atmosphere. 

In  a  standard  mercurial  barometer,  a  vertical  tube  33  inches 
long  rises  from  a  cistern  of  mercury,  the  tube  above  the  level 
of  the  mercury  being  in  a  state  of  perfect  vacuum.  In  Fortin's 
standard  instrument  (fig.  41)  the  small  cistern  has  a  leathern 
bottom,  which  by  means  of  a  thumb-screw  (a)  can  be  tightened 
or  relaxed  so  as  to  raise  or  lower  the  level  of  the  mercury  in  the 
cistern.  The  scale  for  reading  the  height  of  the  column  of 
mercury  is  divided  into  inches,  tenths,  and  half-tenths  (oV)  of 
inches;  and  to  obtain  more  accurate  readings  than  the  scale 
alone  allows,  a  sliding  scale  or  vernier  {b)  is  attached,  which 
serves  to  indicate  the  amount  of  space  occupied  by  the  mercury 
between  the  half-tenth  lines.  The  vernier  scale  is  divided  into 
twenty- five  equal  parts,  which  correspond  to  twenty- four  half- 
tenth  divisions  on  the  barometer  scale.  Consequently  each 
division  on  the  vernier  is  ^V  less  than  a  half-tenth  division  on 
the  barometer  scale,  and  is  therefore  ^V  of  ixj  inch  (=  5^  or 
0002  inch). 

In  order  to  take  an  accurate  observation,  the  eye,  the  zero 
edge  of  the  vernier,  and  the  top  of  the  mercury,  should  aU  be  in 
the  same  horizontal  plane;  hence  the  necessity  of  fixing  the 
barometer  at  a  height  convenient  to  the  observer.  The  tem- 
perature of  the  attached  thermometer  (c)  is  first  noted;  then  the 
level  of  the  mercury  in  the  cistern  is  so  adjusted  that  the  ivory 
point  {d)  projecting  downward  from  the  roof  of  the  cistern 
just  touches  the  surface  of  the  mercury.  This  little  ivory 
point  indicates  the  zero  of  the  scale;  and  since  the  level  of  the 
mercurial  surface  in  the  cistern  varies  with  every  change  of 
atmospheric  pressure,  the  level  of  the  mercur}^  must  be  adjusted 


CLIMATE   AND    METEOROLOGY 


289 


prior  to  each  observation,  to  the  zero  of  the  scale.     Next  read 
off  on  the  barometer  scale  the  division  immediately  below  the 


Fig.  41. — Fortin's  Standard 
b.arometer. 


B 


1 


•9 

'8 

■7 

e 

■5 
■4- 
■3 
.0 

•1 
so 

•9 
■8 
■7 
'6 
•5 
.4. 

■3 
■  2 
■I 
29 


Fig.  42. — Di.\GRAM  of  Barometer 
Scale  and  Vernier. 

A,  scale;  B,  vernier. 


top  of  the  column  of  mercury.     Then  adjust  the  vernier  (fig.  42) 
so  that  its  lowest  line  is  level  with  the  top  of  the  column  of  mer- 

19 


290  HYGIENE  AND  PUBLIC  HEALTH 

cury,  and  the  light  is  just  excluded  between  the  lower  end  of  the 
vernier  and  the  top  of  the  mercury,  and  count  the  number  of 
divisions  on  the  vernier  from  below  upwards,  until  a  line  on  the 
vernier  is  exactly  continuous  with  one  on  the  barometer  scale. 
Multiply  the  number  of  divisions  on  the  vernier  so  obtained 
by  0002,  and  add  the  result  to  the  already  observed  height  on 
the  barometer  scale. ^  Corrections,  by  Glaisher's  tables,  must 
then  be  made  for  temperature  above  32°  F. — for  mercury,  like 
all  other  metals,  expands  with  a  rise  of  temperature.  The 
mercury  falls  about  toW  inch  for  every  foot  ascent  above  sea- 
level,  and  allowance  must  be  made  for  this  if  the  observation  is 
made  at  an  altitude. 

The  barometer  must  always  be  carefully  and  truly  fixed  by 
means  of  a  plumb  line,  in  a  good  light  and  protected  from  sun- 
shine, rain,  and  winds.  Before  fixing,  it  should  always  be  ascer- 
tained if  the  vacuum  above  the  mercury  is  true.  To  do  this, 
unscrew  the  bottom  of  the  cistern  until  the  mercury  is  2  or  3  inches 
from  the  top,  and  then  rather  suddenly  incline  the  instrument. 
If  the  vacuum  is  true,  the  mercury  strikes  against  the  top  of  the 
tube  with  a  sharp  click,  but  a  dull  sound  results  if  air  is  present. 
In  the  latter  case,  screw  up  the  bottom  tightly,  turn  the  instru- 
ment upside  down,  and  tap  the  side  forcibly  until  a  bubble  of 
air  is  seen  to  pass  through  the  mercury  column  into  the  cistern. 
Barometric  observations  are  always  expressed  to  the  third  place 
of  decimals;  and  isobarometric  lines,  as  shown  on  charts,  in- 
dicate areas  over  which  the  barometric  pressures  are  identical. 
If  the  isobars, which  are  drawn  for  each  xV  inch,  are  close  together, 
the  "  barometric  gradient  "  is  said  to  be  steep,  and  the  wind 
velocity  will  be  high. 

The  aneroid  barometer  is  a  small  watch-shaped  metal^  box 
from  which  the  air  has  been  exhausted,  and  in  which  the 
two  flat  surfaces  of  the  box  are  kept  apart  by  a  powerful 
but  sensitive  spring.  The  atmospheric  pressure  acts  upon 
the  spring,  and  is  recorded  on  a  dial.  This  instrument  is 
chiefly  used  for  taking  altitudes.  The  practice  is  to  read 
the  aneroid  to  the  nearest  ^^  inch  both  at  the  commencement 
and  at  the  termination  of  an  ascent,  and  then  to  subtract  one 

1  For  instance,  in  fig.  42  the  mercury  is  shown  to  reach  to  a  little  above 
29-55  inches  on  the  barometric  scale;  taking  the  seventh  line  on  the 
vernier  as  the  line  which  is  exactly  continuous  with  one  cf  the  barometric 
scale,  then  7X-oo2  =  -oi4;  and  the  barometric  reading  is  29-554- "014  = 
29-564  inches  of  mercury. 


CLIMATE    AND   METEOROLOGY 


291 


reading  from  the  other  (ignoring  decimal  points),  and  multiply 
the  difference  by  9,  this  giving  the  height  of  the  ascent  in  feet. 

Example. — 

Reading  at  start=  30-00  inches. 
Reading  at  end  =29*00      ,, 

100 
9 

900  feet  ascended. 

The  weight  of  a  cubic  foot  of  dry  air  at  32°  F.  and  30  inches 

of  mercury  is  566-85  grains.     As  air  expands  -^Ij  of  its  volume 

for  every  degree   rise  Fahrenheit,   the   volume   at   60°  F.,   for 

instance,   is   1+  jK  x  (60- 32)  =  1-057  cubic  feet.     The  weight 

is   inversely   as   volume;   consequently   the   weight   of   a  cubic 

566-85 
foot  of  dry  air  at  60°  F.=  =536-28  grains. 

The  weight  of  a  cubic  foot  of  water  vapour  at  60°  F.  is  5-77 
grains.  Therefore,  the  added  weights  of  a  cubic  foot  of  dry  air 
at  60°  and  of  a  cubic  foot  of  vapour  at  60°  are  536-28+577= 
542-05  grains.  But  dry  air  expands  on  taking  up  moisture, 
and  the  actual  weight  of  a  cubic  foot  of  saturated  air  at  60°  is 
532-84  grains,  or  3-44  grains  less  than  the  weight  of  an  equal 
volume-  of  dry  air 
at  that  temperature, 
because  the  cubic  foot 
of  originally  dry  air  is 
now  more  than  a  cubic 
foot.  This  fact  ex- 
plains the  fall  of  the 
barometer  when  the 
moisture  in  the  air  is 
increasing  and  a  fall 
of  rain  is  imminent. 

Robinson's  Wind 
Anemometer  is  an 
instrument  which 
records  the  velocity 
of    the    wind.      The 


Fig.  43. — Robinson's  Anemometer. 


figure  (43)  sufficiently  explains  the  construction  of  the  instru- 
ment. The  revolving  cups  set  in  action  a  train  of  clockwork, 
and  the  velocity  of  the  wind  is  recorded  on  a  series  of  dials. 


292 


HYGIENE    AND    PUBLIC    HEALTH 


The  cups  travel  at  a  rate  equal  to  only  one-third  that  of  the 
wind,  and  allowance  is  made  for  this  fact  in  graduating  the 
instrument.  The  square  of  the  velocity  in  miles  per  hour, 
multiphed  by  0005,  gives  the  wind  pressure  in  pounds  per 
square  foot;  and  on  the  other  hand,  the  square  root  of  200 
times  the  wind's  pressure  gives  the  velocity. 

The  instrument  must  be  kept  clean  and  well  oiled,  and  should 
be  fixed  at  least  20  feet  from  the  ground,  and  away  from  buildings. 
The  average  velocity  of  the  wind  is  from  six  to  eight  miles  per 
hour. 

On  the  Beaufort  scale,  in  a  "  light  wind,"  the  air  travels  at  a 
rate  of  13  miles  per  hour;  in  a  "  moderate 
breeze,"  23;  in  a  "  strong  breeze,"  34;  and 
in  a  "  gale,"  65. 

All  wind  direction  observations  by  vanes, 
etc.,  should  be  recorded  to  the  nearest  point 
of  the  compass. 

The  instruments  which  register  the  moisture 
in  the  atmosphere  are  known  as  hygrometers. 
Of  these  there  are  two  distinct  classes,  i.e., 
those  which  indicate  the  dew  point  directly, 
and  those  from  which  the  dew  point  is 
indirectly  determined. 

In  the  former  class  the  air  is  cooled  until 
the  moisture  is  deposited  on  a  bright  surface 
to  which  a  thermometer  is  attached,  the  latter  indicating  the 
temperature  of  the  dew  point. 

In  Daniell's  hygrometer  (fig.  44)  ether  is  placed  in  the  lower 
bulb,  and  the  other  bulb  (which  contains  nothing  but  ether 
vapour)  is  covered  with  muslin  moistened  with  ether.  This 
ether  on  the  muslin  evaporates  into  the  air,  and  the  loss  of  heat 
so  occasioned  condenses  the  ether  vapour  inside  the  bulb,  causing 
evaporation  from  the  ether  inside  the  other  (lower  bulb).  The 
lower  bulb  thus  becomes  gradually  colder,  and  chills  the  air  sur- 
rounding it,  until  a  temperature  is  reached  at  which  the  air  is 
compelled  to  part  with  some  of  its  moisture,  which  condenses 
upon  the  bright  metal  band  surrounding  the  bulb.  Directly 
this  takes  place  the  temperature  of  the  dew  point  is  read  off  from 
the  attached  thermometer.  The  temperature  at  which  the  dew 
disappears  is  next  observed,  and  the  mean  between  these  two 
temperatures  is  taken  as  the  dew  point.     In  Regnault's  instru- 


FiG.  44. — Daniell's 
Hygrometer. 


CLIMATE   AND   METEOROLOGY 


293 


ment  (fig.  45)  one  cylinder  is  half  filled  with  ether,  and  the  other 
is  left  empty,  thermometers  being  inserted  in  both  cylinders. 
An  aspirator  communicates,  by  means  of  the  hollow  upright,  with 
both  cylinders,  and  when  this  is  put  in  action  air  is  drawn  through 
them.  The  passage  of  the  air  through  the  evaporating  ether 
soon  cools  it  down  to  the  dew  point,  and  then  the  bright  metal 
surface  surrounding  the  lower  part  of  the  cylinder  becomes 
dulled  with  moisture.  The  temperature  recorded  at  that  instant 
by  the  thermometer  in  the  ether  is  the  temperature  of  the  dew 
point,  the  second  thermometer  simply  showing  the  temperature 


Fig.  45. — Regnault's  Hygrometer. 


of  the  air  at  the  time  of  observation.  In  Dines'  instrument 
a  vessel  which  holds  ice-water  has  a  bright  metal  plate  with  an 
attached  thermometer  in  its  roof.  As  the  cold  water  is  made 
to  flow  under  the  plate,  the  outside  air  in  contact  with  it  becomes 
chilled;  and  when  the  dew  point,  as  shown  by  the  deposition  of 
dew,  is  reached,  it  can  be  read  off  from  the  attached  thermometer. 
Wet  and  Dry  Bulb  Hygrometer. — This  instrument  consists  of 
two  absolutely  identical  thermometers  mounted  on  a  stand. 
In  the  wet  bulb  thermometer  the  bulb  is  kept  moist  by  being 
covered  with  mushn,  one  end  of  which  dips  into  a  small  vessel  of 
distilled  or  rain  water,  so  that  moisture  ascends  by  capillary 


294 


HYGIENE   AND    PUBLIC   HEALTH 


attraction.  The  evaporation  of  moisture  from  the  wet  bulb, 
which  takes  place  so  long  as  the  surrounding  air  is  not  saturated, 
causes  loss  of  heat,  and  the  wet  bulb  reads  lower  than  the  dry 
bulb.  Both  the  vessel  containing  water  and  the  wet  bulb  must 
be  sufficiently  far  from  the  dry  bulb  to  insure  that  the  readings 
of  the  latter  are  not  affected  by  the  evaporation.  The  instrument 
must  be  exposed  in  the  shade  and  protected  from  air  currents  and 

direct  sunshine,  both  of  which, 
by  increasing  evaporation,  would 
cause  the  wet  bulb  thermometer 
to  indicate  a  temperature  not 
strictly  due  to  the  hygrometric 
state  of  the  atmosphere.  If  the 
muslin  becomes  frozen  in  the 
winter,  the  two  thermometers 
will  read  the  same;  then  the  wet 
bulb  should  be  brushed  over  with 
cold  water,  and  the  evaporation 
which  will  go  on  from  the  frozen 
surface  will  enable  a  proper 
reading  to  be  taken. 

From  the  readings  of  the  dry 
and  wet  bulbs  can  be  ascertained 
— the  relative  humidity  of  the  air, 
i.e.,     the     amount    of    moisture 
present    in    air,   expressed    as    a 
percentage   of   the   amount   just 
necessary    to    cause    saturation; 
the  dew  point,  i.e.,  the  tempera- 
ture   at    which    the    amount    of 
moisture  actually  present  in  the 
air  causes   saturation ;    and    the 
weight  of  vapour  in  a  cubic  foot  of  air,  from  which  can  be  deduced 
the  additional  weight  of  vapour  necessary  to  cause  saturation, 
or  the  drying  power  of  the  air. 

The  relative  humidity  is  found  from  tables.  The  greater 
the  difference  between  the  dry  and  wet  bulbs,  the  lower  is  the 
relative  humidity.  If  the  dry  and  wet  bulbs  record  the  same 
temperature,  the  air  is  completely  saturated  with  moisture. 

The  dew  point  can  be  determined  by  the  equation :  Dew  point 
=  T'^-F  (T^-TJ;  where  T^  is  the  dry  bulb  temperature,  T^.  is 


Fig.  46. 


—  Wet  .\nd  Dry  Bulb 
Hygrometer. 


CLIMATE   AND    METEOROLOGY  295 

the  wet  bulb  temperature,  and  F  the  factor  opposite  the  dry 
bulb  temperature  found  in  Glaisher's  tables. 

In  De  Saussure's  instrument  {the  Jiair  hygrometer) ,  a  hair  freed 
from  fat  by  ether  is  fixed  at  one  end,  and  this  hair  contracts  with 
lesser  and  expands  with  higher  degrees  of  humidity.  The  hair 
is  kept  stretched  by  a  small  weight,  the  connecting  cord  of  which 
is  led  round  a  pulley;  and  an  index  needle  attached  to  the  pulley 
indicates  the  relative  humidity  on  an  empirically  graduated 
scale  of  relative  humidities.  The  instrument  is  standardized 
by  first  wetting  the  hair  and  noting  whether  it  accurately  registers 
saturation  on  the  scale  (i.e.,  lOo) ;  but  it  is  necessary  to  frequently 
verify  the  readings  by  other  methods. 

The  "  elastic  force  of  vapour,"  or  "  the  tension  of  aqueous 
vapour,"  is  the  amount  of  the  barometric  pressure  which  is  due 
to  the  aqueous  vapour  in  the  atmosphere.  If  the  temperature 
of  the  air  is  lowered,  and  with  it  the  tension  of  aqueous  vapour, 
a  temperature  will  sooner  or  later  be  reached  at  which  the  air  is 
saturated  with  moisture ;  and  then  the  sHghtest  further  reduction 
in  temperature  will  cause  a  deposition  of  dew  ("  dew  point  "). 
The  tension  of  aqueous  vapour  is  ascertained  from  tables  or  b}' 
formula.  The  relative  humidity  can  be  calculated  by  dividing 
the  elastic  force  of  aqueous  vapour  at  the  temperature  of  the 
dew  point  by  the  elastic  force  of  the  aqueous  vapour  at  the 
temperature  of  the  air,  and  then  multiplying  by  loo. 

Example. — The  dry  bulb  temperature  is  62°  F.,  and  that  of  the  wet  bulb 
is  56°  F.     The  dew  point  is  therefore 

62--{  (62-56)x  1-86  ^  =  50-84°  F. 
The  aqueous  tension  at  62°  F.  is  (from  Glaisher's  tables)  0-556  of  an  inch 
of  mercury,  and  that  at   50-84°  F.  is  0-372  of  an  inch.       The  relative 

o*  "Xy^ 
humidity  is,  therefore,  ^  x  ioo  =  66-o  per  cent,  of  saturation. 

0-556 

If  the  relative  humidity  at  61°  F.  is  70,  the  amount  of  vapour 
in  a  cubic  foot  is  70  per  cent,  of  the  amount  of  moisture  (6  grains) 
which  saturates  a  cubic  foot  of  air  at  that  temperature,  or  xVt)  of 
6=4-2  grains;  and  the  drying  power  of  a  cubic  foot  of  the  air  is 
6  — 4-2  =  1-8  grains. 

Atmometers ,  for  determining  the  amount  and  rate  of  evapora- 
tion, have  been  devised.  In  these  instruments  a  known  volume 
and  weight  of  water  is  exposed  in  a  receptacle,  so  as  to  present 
a  known  surface  area  to  the  atmosphere;  and  the  evaporation 
in  a  given  time  is  determined  by  the  loss  either  in  volume  or  in 
weight  of  the  original  water. 


296 


HYGIEI^E    AND  ^CTSLIC  "HEALTH 


The  weii,^'ht  of  moisture  which  a  cubic  foot  of  dry  air  can  take 
up,  before  it  is  saturated,  varies  with  the  temperature.  The 
higher  the  temperature,  the  larger  is  the  amount  of  vapour  which 
can  be  held,  as  the  following  table  shows. — 

Gr.\ins  of  Vapoun    ro  saturate  a  Cubic  Foot  of  Dry  Air 
(.'Approximate). 


30°  F.  2  grains 

66°  F. 

7  grains 

80°  F.  1 1  grains 

41°  F.  3        ,, 

70°  F. 

8 

83°  F.  12 

49°  F.  4       „ 

74°  F. 

9 

86°  F.  13 

S0°  F.  =; 

77°  F. 

10 

88°  F.  14 

61°  F.  6       ., 

Hence,  when  warmer  air,  already  moisture  laden,  is  chilled, 
the  moisture  representing  the  difference  between  what  it  originally 
held  and  what  it  is  capable  of  holding  at  the  reduced  temperature 
is  deposited  in  the  form  of  dew  or  rain. 

Rain  Gauge. — This  instrument  consists  of  a  vessel  supporting 
at  its  top  a  circular  funnel  which  collects  the  rainfall.  The 
vessel  must  be  sunk  in  level  ground,  away  from  shrubs  and  build- 
ings, to  such  a  depth  that  the 
collecting  surface  is  one  foot  from 
the  ground.  A  measuring  glass 
graduated  according  to  the  area 
of  the  funnel,  so  as  to  indicate  the 
fall  of  rain  as  decimals  of  an  inch, 
is  required.  The  area  of  the  top 
of  the  circular  funnel  (the  receiv- 
ing surface  for  the  rain)  is  usually 
50  square  inches.  To  graduate  the 
measuring  glass  for  a  funnel  of 
this  area,  50  cubic  inches  of  water 
are  poured  into  it,  and  a  mark 
placed  at  the  level  the  fluid  stands 
at.  Then  if  the  rainfall  collected 
on  50  square  inches  should 
measure  the  50  cubic  inches, 
each  square  inch  of  surface  has 
collected  one  cubic  inch  of  water, 
and  the  rainfall  is  "  one  inch."  But  the  glass  below  the  mark  is 
divided  into  100  equal  parts,  so  that  each  division  indicates  a 
fall  of  T^xT  or  o-Qi  inch  of  rain.  The  readings  are  generally  taken 
daily  at  g  a.m. 


Fig.  47. — Rain  Gauge. 


CLIMATE    AND    METEOROLOGY  297 

In  time  of  snow,  the  collected  snow  should  be  melted  by  adding 
a  measured  quantity  of  warm  water  to  it,  the  extra  water  derived 
from  the  snow  being  recorded  as  rain-water.  The  average  depth 
of  the  adjacent  snow  should  also  be  noted. 

In  Crosley's  self- registering  rain  gauge  every  j^o  inch  of  rain- 
fall is  recorded  on  a  dial.  The  rainfall  collected  gradually  fills 
one  compartment  of  a  small  bucket  divided  into  two  compart- 
ments, and  balanced  on  a  pivot.  When  one  compartment  is  full, 
the  bucket  tips  and  causes  an  index  to  record,  and  the  second 
compartment  then  commences  to  fill. 

Aqueous  vapour  requires  free  surfaces  for  its  condensation. 
When  air  is  filtered,  no  cloud  of  condensed  vapour  can  be  formed. 
"  Wet  fogs  "  result  when  the  particles  of  suspended  matter  are 
relatively  few  and  the  condensed  moisture  excessive,  whereas 
"  dry  fogs  "  occur  when  the  smoke  and  dust  are  relatively 
abundant.  When  the  films  of  moisture  are  discoloured  by  the  pro- 
ducts of  coal  combustion,  a  yellow  or  "  pea  soup  "  fog  will  result. 

The  death-rate  generally  increases  as  a  result  of  town  fogs, 
and  the  increase  is  ascribed  to  the  irritating  effects  of  the  im- 
purities in  the  atmosphere  upon  the  lungs,  and  to  the  sudden  fall 
of  temperature  which  takes  place  on  the  occurrence  of  the  fog. 
Fogs  lead  to  a  considerable  loss  of  that  important  element, 
sunshine,  in  our  great  towns;  for,  as  a  rule,  when  the  town  is 
enveloped  in  fog  there  is  a  cloudless  sky  above. 

Clouds  consist  of  collections  of  condensed  aqueous  vapour. 
The  principal  forms  which  they  assume  are:  (i)  The  cirrus,  con- 
sisting of  separate  fine  feathery  formations,  generally  white  in 
colour;  (2)  the  stratus,  consisting  of  a  smooth  horizontal  stratum 
of  cloud;  (3)  the  nimbus,  constituting  the  raining  clouds,  of  dark 
coloured,  irregular  forms;  and  (4)  the  cumulus,  or  heavy,  thick, 
well  defined  clouds,  generally  rounded  off  in  shape.  Two  or 
more  of  these  four  principal  forms  may  be  mixed  together,  giving 
rise  to  appearances  which  are  defined  as  "  cirro-stratus,"  "  cirro- 
cumulus,"  "  strato-cumulus,"  "  cumulo-nimbus,"  etc. 

Thermometcys  measure  the  temperature  from  the  amounts  of 
expansion  and  contraction  of  certain  bodies  when  these  are 
exposed  to  varying  degrees  of  heat  and  cold.  Mercury  is  com- 
monly employed,  because  of  its  very  low  freezing  point  (  -  38"  F.) 
and  its  high  boihng  point  (675°  F.) ;  but  alcohol  is  preferred 
when  very  low  temperatures  may  have  to  be  recorded,  because 
it  does  not  freeze  at  the  greatest  known  degree  of  cold. 


^9^  HYGIENE    AND    PUBLIC    HEALTH 

The  instruments  are  graduated  from  the  fixed  points  of  freezing 
and  boihng  water,  by  plunging  them  into  melting  ice  and  boihng 
water,  respectively,  at  the  standard  pressure.  On  the  Centigrade 
scale  the  freezing  and  boiling  points  are  o°  and  ioo°  respectively, 
while  on  the  Fahrenheit  scale  the  freezing  point  is  32°  and  the 
boiling  point  212°;  therefore,  to  convert  Centigrade  to  Fahren- 
heit, multiply  the  former  figure  by  5  and  add  32,  while  to  convert 
Fahrenheit  to  Centigrade  subtract  32  and  then  multiply  by  |. 

Maximum  thermometers  are  instruments  designed  to  register 
the  highest  temperature  reached  during  the  period  of  exposure 
of  the  instrument;  in  these  the  temperature  is  registered  by 
mercury.  The  registration  is  effected  by  either  breaking  the 
column  of  mercury  by  an  air  bubble,  or  by  a  slight  narrowing  of 
the  tube  near  the  bulb.  In  either  case  the  natural  cohesion  of 
the  metal  when  contracting  is  overcome,  and  the  mercury  always 
remains  at  the  highest  point  reached.  Another  method  is  to 
insert  a  small  piece  of  sohd  glass  enamel  in  the  bend  near  the 
bulb;  this,  acting  as  a  valve,  allows  the  mercury  to  pass  on  one 
side  of  it  as  it  expands,  but  does  not  allow  it  to  return  on  coohng. 
In  hanging  a  maximum  thermometer,  it  is  necessary  to  see  that 
the  end  of  the  tube  furthest  from  the  bulb  is  shghtly  inclined 
downwards,  to  assist  in  preventing  the  return  of  any  portion  of 
the  column  of  mercury  into  the  bulb  on  a  decrease  of  temperature. 
Before  reading  the  instrument,  the  end  furthest  from  the  bulb 
should  be  gently  elevated  to  an  angle  of  about  45°. 

Minimum  thermometers  record  the  lowest  temperature  reached. 
They  are  alcohol  instruments,  with  an  index  in  the  alcohol 
(Rutherford's)  which  moves  with  the  spirit  on  contraction  by 
cold,  owing  to  capillary  attraction,  but  not  on  expansion,  and 
is  therefore  left  registering  the  lowest  temperature.  The  end  of 
the  index  furthest  from  the  bulb  indicates  the  minimum  tem- 
perature. Occasionally  air  bubbles  appear  in  the  alcohol  and 
fix  the  index.  They  can  be  removed  by  holding  the  thermometer 
with  the  bulb  downwards,  and  swinging  it  round  rapidly  at  arm's 
length.  These  instruments  should  be  hung  so  that  the  bulb  end 
is  I  inch  lower  than  the  other  end,  because  then  the  index  is  less 
likely  to  be  affected  by  a  rise  in  temperature. 

The  so-called  "  earth  "  thermometer  is  a  maximum  thermometer 
which  is  suspended  by  a  chain  in  a  stout  iron  tube,  5  feet  long, 
which  is  provided  with  a  pointed  metal  cap.  By  this  means  the 
temperature  of  the  earth  at  depths  up  to  nearly  5  feet  can  be 


CLIMATE  AND  METEOROLOGY 


299 


ascertained.     In  taking  an  observation  the  thermometer  must 
be  quickly  drawn  up  and  read. 

In  Six's  thermometer  (ftg.  48)  there  is  a  U-tube,  the  middle 
part  of  which  is  occupied  by  mercury.  The  bulb  [a)  and  both 
tubes  above  the  mercury  contain  alcohol,  in  which  are  two  steel 
indices,  which  are  brought  by  means  of  a  magnet,  to  rest  upon 
either  column  of  mercury ;  and  {h)  is  a  small  chamber  containing  air. 
On  a  rise  of  temperature,  the  alcohol,  expanding  in  the  bulb  (a),  de- 
presses the  mercury  levelin  one  arm,  and  therefore 
raises  it  in  the  other,  the  maximum  temperature 
being  indicated  by  the  position  reached  by  the 
lower  end  of  the  index.  Conversely,  as  the 
temperature  falls  the  alcohol  in  the  bulb  con- 
tracts, and  the  pressure  of  the  air  in  the  chamber 
{b)  depresses  the  mercury  level  in  the  arm  im- 
mediately beneath,  and  therefore  raises  the 
mercury  level  in  the  other  arm,  in  which  the 
index  then  registers  the  lowest  temperature 
experienced.  Thus,  in  the  arm  (c)  maximum 
temperatures  are  registered,  and  in  the  arm 
{d)  minimum  temperatures. 

A  barograph  and  a  thermograph  are  instru- 
ments which  furnish  a  record  of  the  barometric 
pressure  and  of  the  temperature  for  the  whole 
twenty-four  hours  of  the  day  and  night.  The 
records  are  traced  on  slowly  revolving  drums 
worked  by  clockwork.  The  instruments  require 
repeated  standardizing.  In  the  recording 
aneroid  barometer  the  fluctuations  of  atmos- 
pheric pressure  act  upon  a  series  of  aneroid 
vacuum  chambers,  a  sensitive  index  attached 
to  the  latter  recording  the  results.  In  one 
form  of  thermograph  the  record  is  continuously  marked  by  an 
index  attached  to  a  delicate  metal  spring,  the  expansion  and  con- 
traction of  which  is  dependent  on  the  atmospheric  temperature. 

Isochimenal  lines  are  lines  drawn  through  districts,  as  shown 
on  a  chart  or  map,  having  the  same  winter  temperature;  and 
isothermal  lines  similarly  indicate  districts  with  the  same  mean 
annual  temperatures. 

Shade  maximum  and  minimum  thermometers  should  be  placed 
horizontally  in  the  shade,  or  in  a  Stevenson's  louvred  box,  4  feet 


fp^' 

■ 

1 

■ 

b 

P 

7 

» 1 

1^1 

1  n 

rE^^cE 

EJi 

o]| 

g.]: 

'"1 

ID 

■     ; 

ii:i 

20' 

'    ' 

igJ 

30: 

50 : 

;7o| 

60 

:bo  1 

7C 

■  1 

;E0 

P 

; 

:    ; 

:30 

110 

\f 

:20 

d 

KO 

i 

1 

J  111 

P''^'"'*>^il 

Fig.     48.  —  Six's 
Thermometer. 


300 


HYGIENE  AND  PUBLIC  HEALTH 


above  the  ground  and  al  least  20  feet  away  from  buildings  or 
other  sources  of  radiation. 

The  vaamm  solar  radiation  thermometer  (fig.  49)  is  a  mercurial 
maximum  self-registering  instrument,  with  a  blackened  bulb, 
which  absorbs  the  sun's  rays.  It  is  placed  in  a  glass  case  from 
which  air  is  exhausted;  thus  protecting  the 
bulb  from  loss  of  heat,  which  would  ensue  if 
the  bulb  were  exposed,  owing  to  atmospheric 
currents  and  the  absorption  of  heat  by  aqueous 
and  other  vapours.  This  instrument  is  placed 
4  feet  above  the  ground,  and  is  directly  exposed 
to  the  sun's  rays.  The  bulb  should  point  south- 
east in  this  country.  The  difference  between 
the  maxima  in  the  sun  and  in  the  shade  is  a 
measure  of  solar  radiation,  or  of  the  power  of 
the  sun's  rays. 

Other  instruments  which  may  be  found 
useful  are:  A  terrestrial  radiation  thermometer, 
which  is  merely  a  minimum  shade  thermometer 
placed  close  to  the  ground,  the  bulb  resting  on 
grass— the  difference  between  this  minimum 
temperature  and  the  air  minimum  in  the  shade 
being  taken  as  the  amount  of  terrestrial  radia- 
tion; a  sunshine  recorder  (Campbell-Stokes', 
fig.  50),  a  little  instrument  by  which  the  rays 
of  the  sun  are  concentrated  on  to  a  strip  of 
millboard  stretched  in  a  frame  at  the  proper 
focal  distance  from  a  large  spherical  lens. 
When  the  sun  shines,  a  charred  line  is  burnt 
in  the  millboard,  and  when  hidden  by  clouds 
the  record  ceases.  Results  are  best  expressed 
as  a  percentage  of  the  possible  sunshine;  i.e., 
if  the  sun  is  above  the  horizon  ten  hours,  and 
the  record  is  but  one  hour,  the  sunshine 
equals  10  per  cent,  of  the  possible  amount. 

Jordan's  instrument  is  a  sunlight  rather  than  a  sunshine  re- 
corder. By  this  instrument  a  straight  line  of  sunlight  is  recorded 
on  sensitive  cyanotype  paper  placed  in  two  semicircular  dark 
chambers.  The  sunhght,  being  admitted  through  small  apertures 
in  the  sides,  travels  over  the  sensitive  paper  or  chart  by  reason 
of  the  earth's  rotation,  and  leaves  behind  a  record  of  the  duration 


Fig.  49.  —  SoL.\R 
Radiation 
Thermometer. 


CLIMATE    AND    METEOROLOGY  301 

of  sunlight  and  the  relative  degrees  of  its  intensity.  The  in- 
strument must  be  carefully  adjusted  to  the  meridian  and  to 
the  latitude  of  the  place.  To  this  end  the  base  plate  of  the 
instruments  must  be  inclined  until  the  index  points  to  the  divi- 
sions on  the  arc  corresponding  to  the  latitude  of  the  station;  then 
turn  the  instrument  until  it  faces  due  south,  taking  care  that  the 


^  .w.     ^     .        ..^NSHINE    RECORDER. 

base  is  perfectly  level.  When  the  sun  is  on  the  meridian,  the 
sunshine  passing  through  the  apertures  should  fall  on  the  chart 
line  indicating  twelve  o'clock.  One  box  takes  the  records  for 
the  forenoon,  and  the  other  for  the  afternoon,  thus  enabling  the 
charts  to  be  changed  without  interfering  with  a  continuous 
record. 

Atmospheric  Electricity. 

The  atmosphere  is  charged  with  electricity,  which  is  chiefly 
positive  in  fine  weather  and  negative  in  wet.  The  sources  of  this 
electricity  are:  (i)  Vegetation,  (2)  evaporation  from  waters  con- 
taining salts  in  solution,  (3)  the  unequal  distribution  of  heat, 
leading  to  atmospheric  friction,  and  (4)  combustion  at  the  earth's 
surface  (giving  off  positive  electricity).  Vegetation  furnishes 
electricity  by  the  evaporation  of  moisture,  and  by  the  giving 
off  of  CO2  and  O  charged  with  positive  electricity. 

When  clouds  charged  with  different  electricities  (positive  and 
negative)    approach  each  other,   a  thunderstorm  results.     The 


302  HYGIENE    AND    PUBLIC    HEALTH 

heat  generated  along  the  track  of  the  electric  discharge  causes 
the  "  lightning,"  and  thelthunder  probably  results  from  the 
sudden  expansion  of  the  air  consequent  upon  the  lightning,  and 
the  subsequent  inrush  of  air  to  restore  the  resulting  partial 
vacuum. 

Lightning  rods  are  generally  of  iron,  of  about  i  inch  in  diameter, 
and  pointed  with  copper.  They  are  carefully  insulated,  one 
end  being  buried  in  the  ground.  They  must  be  fixed  at  a  dis- 
tance from  any  of  the  metal  pipes  of  a  building. 


CHAPTER  VII 
EXERCISE  AND  CLOTHING 

Exercise. 

The  effects  of  exercise  on  the  body  are  as  follows: — 

I.  Increased  force  and  frequency  of  the  heart's  action,  and 
by  consequence  the  increased  circulation  of  the  blood  through 
all  parts  of  the  body.  2.  The  pulmonary  circulation  being 
quickened,  more  carbonic  acid  and  moisture  are  eliminated. 
The  amount  of  air  inspired  and  expired  is  largely  increased. 
3.  The  action  of  the  skin  is  heightened,  and  perspiration  becomes 
marked.  The  dilatation  of  the  cutaneous  blood  vessels,  and  the 
evaporation  of  the  sweat  from  the  surface  of  the  body,  regulate 
the  temperature  and  prevent  any  rise  above  the  normal.  4.  The 
water  and  salt  of  the  urine  are  decreased  owing  to  the  large 
cutaneous  secretion,  but  the  nitrogen  eliminated  (in  the  form 
of  urea,  uric  acid,  and  extractives)  remains  about  the  same. 
In  the  period  of  rest  following  excessive  exercise,  the  nitrogen 
elimination  may  be  shghtly  increased.  5.  The  voluntary  muscles 
are  brought  into  active  play ;  the  circulation  of  the  blood  through 
them  is  accelerated;  waste  products  are  rapidly  carried  away 
for  excretion ;  whilst  the  material  to  replace  waste  is  brought  to 
them. 

It  is  thus  seen  that  exercise,  which  means  muscular  action, 
involves  more  rapid  combustion,  as  shown  by  the  increased 
ehmination  of  carbonic  acid  and  water.  Thirst  and  appetite 
are  created,  and  water  and  carbonaceous  foods  are  required  to 
supply  the  waste;  whilst  an  increased  amount  of  nitrogenous 
food,  during  or  after  periods  of  exercise,  is  necessary  to  replace 
the  waste  caused  by  the  nitrogenous  tissues  performing  their 
function  of  regulating  oxidation. 
Regular  exercise  in  the  open  air  is  most    essential  to  brain 

303 


304  HYGIENE  AND  PUBLIC  HEALTH 

workers,  to  purify  the  blood  from  waste  matters,  and  to  stimulate 
the  action  of  the  bowels;  but  exercise  of  the  muscles  generally 
is  necessary  for  the  healthy  performances  of  all  the  functions  of 
the  body.  Well  developed  muscles  are  requisite  for  all  active 
spontaneous  movements.  Over  development  of  isolated  groups 
of  muscles,  such  as  may  be  produced  by  too  specialized  physical 
exercises  or  gymnastic  feats,  should  not  be  sought  for,  as  they 
do  not  tend  to  the  harmonious  working  of  all  parts  of  the  bodj^ 
and  may  actually  hamper  free  movements  in  unaccustomed 
directions.  The  aim  should  be  to  encourage  general  strength 
and  activity,  and  not  to  attain  special  expertness  in  feats  of 
strength  controlled  by  isolated  groups  of  muscles.  The  natural 
exercises,  such  as  walking,  running,  riding  on  horseback,  fencing, 
boxing,  rowing,  and  all  the  various  games  in  which  co-ordinated 
movements  of  many  muscles  (hands,  fingers,  arms,  legs, 
trunk,  head,  neck,  and  eyes)  are  concerned,  are  superior 
both  for  physical,  mental,  and  moral  training,  to  physical 
exercises  carried  out  to  the  word  of  command.  Games  inculcate 
courage,  control  of  the  temper,  self-restraint,  and  obedience  to 
discipline,  combined  with  the  desire  to  win ;  but  the  latter  should 
not  be  allowed  to  overrule  fairness  and  good  temper  to  opponents, 
and  the  desire  to  show  individual  excellence  should  always  be 
subordinated  to  the  desire  to  do  what  is  best  for  one's  side. 

After  active  exercise  the  body  should  be  well  washed  with 
soap  and  water  to  remove  the  secretion  from  the  sweat  and 
sebaceous  glands,  which,  if  left  on  to  dry,  becomes  mixed  with 
shed  epidermic  scales  from  the  scarf  skin,  and  renders  the  skin 
dirty  and  damp.  The  damp  skin  causes  surface  cooling,  and 
often  gives  rise  to  a  dangerous  internal  chill. 

If  the  exercise  is  too  severe  the  heart  is  overstrained,  breath- 
lessness  and  palpitation  are  brought  on,  and  the  pulse  becomes 
small,  very  frequent  and  irregular.  Gymnastic  and  other  mus- 
cular exercises,  which  involve  the  fixation  of  the  walls  of  the 
chest  for  an  undue  period  (more  than  a  few  seconds),  and  con- 
sequent arrest  of  the  respiratory  movements,  are  particularly 
liable  to  produce  heart  strain  and  subsequent  dilatation  of  the 
heart.  An  indication  of  the  possible  injurious  action  that  ma}' 
result  is  afforded  by  the  occurrence  of  congestion  of  the  veins 
and  lividity  of  the  face  during  the  muscular  effort.  In  the 
British  Army,  since  the  modified  Swedish  forms  of  exercises 
have  replaced  the  old-established  gymnastic  exercises,  and  the 


EXERCISE    AND    CLOTHING  305 

drill  with  constantly  expanded  chest  has  been  abandoned,  there 
has  been  a  coincident  diminution  of  cases  of  disordered  action 
of  the  heart  and  valvular  heart  troubles  The  physical  training 
exercises  which  least  interfere  with  the  normal  rhythm  of  res- 
piration, and  which  do  not  necessitate  any  postures  implying 
strain  or  tension  of  the  chest  and  abdomen  for  prolonged  periods, 
are  the  most  suitable,  especially  for  the  young  of  both  sexes. 
Prolonged  exertion  of  a  severe  kind  tends  to  cause  cardiac  pain 
and  palpitation,  and  may  give  rise  to  hypertrophy  of  the  left 
ventricle,  if  the  over-exertion  is  habitual.  Rupture  of  blood- 
vessels from  over-exertion  is  uncommon  before  middle  life.  Thus 
hammer-men  in  iron  factories,  owing  to  the  excessive  strain  they 
are  put  to,  sometimes  develop  disease  of  the  aorta,  ending  in 
aneurism;  and  also  disease  of  the  valves  of  the  heart.  In  others, 
degenerative  changes  gradually  appear  in  the  organs  of  circula- 
tion, which  ultimately  unfit  them  for  strenuous  labour,  and  lead 
to  conditions  of  permanent  ill-health. 

The  muscles,  including  the  cardiac  muscle,  require  rest  to  get 
rid  of  the  accumulated  products  of  their  action  (possibly  lactic 
acid),  and  to  take  in  a  fresh  store  of  oxygen.  Without  definite 
periods  of  rest  suited  to  the  kind  of  exercise,  the  muscles  become 
exhausted,  and  their  contractions  are  gradually  enfeebled,  until 
they  cease  altogether.  The  diastole  of  the  heart  is  quite  sufficient 
for  its  recuperation  when  the  body  is  at  rest. 

The  diet  of  men  in  training  should  differ  little,  if  at  all,  from 
an  ordinary  diet.  The  amount  of  fat  and  nitrogenous  food  may 
be  somewhat  increased  out  of  the  usual  proportion  to  the  carbo- 
hydrates; but  to  deprive  men  of  bread,  potatoes,  and  vegetables, 
and  to  feed  them  on  half-raw  beefsteaks — as  was  formerly  so 
largely  done — is  a  ready  means  of  causing  the  "  staleness  "  so 
well  known  to  trainers.  Plenty  of  water,  in  small  quantities 
at  a  time,  should  be  allowed  as  the  system  demands.  After  a 
few  days  of  training,  excessive  thirst  and  excessive  sweating 
disappear,  and  the  right  balance  between  income  and  outcome 
of  fluid  is  quickly  struck.  The  capacity  of  the  chest  and  the 
elasticity  of  the  lungs  and  chest  walls  are  notably  increased  by 
well  regulated  training,  especially  by  training  for  rowing. 

From  numerous  observations  it  has  been  deduced  that  an 
ordinary  day's  physical  work  for  a  healthy  man  is  equivalent 
to  300  tons  raised  i  foot  (foot  tons).  This  is  an  amount  of  work 
which  can  be  sustained  day  after  day  without  loss  of  weight  and 

20 


3o6 


HYGIENE    AND    PUBLIC   HEALTH 


without  inconvenience.  Work  represented  by  over  400  foot 
tons  daily  cannot  be  kept  up  unless  the  diet  is  much  increased, 
and  even  then  there  is  likely  to  be  loss  of  weight  and  muscular 
vigour.  It  has  been  shown  that  a  man  walking  on  a  level  surface 
at  the  rate  of  three  miles  per  hour  does  work  equivalent  to  raising 
his  own  weight,  plus  the  weight  he  carries,  a  height  equivalent 
to  one-twentieth  the  distance  walked.  At  quicker  rates  of  speed 
this  "co-efficient  of  traction"  more  nearly  approaches  unity; 
thus,  at  four  miles  an  hour  it  is  between  one-sixteenth  and  one- 
seventeenth,  and  at  eight  miles  per  hour  the  co-efhcient  is  barely 
one-tenth, 
amount  of  work  done  by  a  man  in  walking 


The  following  formula  is  useful  for  estimating  the 


(^. 


Let  W=  weight  of  the  man  in  lbs., 

W'=  weight  he  carries, 

D=  distance  walked  in  feet, 

C  =  co-efficient  of  traction. 

^,,        (W+W')xD      „     ,     ,, 

I  hen  ^ ' xC  =  foot  tons. 

2,240 

240  is  the  number  of  pounds  in  a  ton.) 


About  seventeen  miles  at  three  miles  an  hour,  for  a  man 
weighing  150  pounds  and  carr3ang  no  weight,  will  be  found  to 
amount  to  an  average  day's  work  of  300  foot  tons. 


Clothing. 

The  ordinary  garments  of  civilized  life  are  made  either  of  one, 
or  a  mixture  of  two  or  more,  of  the  following  materials : — Cotton 
and  linen  from  the  vegetable  kingdom;  wool  and  silk  from  the 
animal  kingdom. 

Cotton  materials  have  a  smooth,  tine  texture,  but  not  equal  in 
these  respects  to  linen.     Under  the  microscope  cotton  is  seen  to 


Fig.  51. — Cotton  Fibrks  (  x  about  200). 

consist  of  flattened  fibres  with  well-marked  twists  in  their  course. 
There  are  no  joints  or  nodes,  and  no  branching  fibres  (fig.  51). 


EXERCISE    AND    CLOTHING 


307 


Cotton  garments  arc  durable,  and  do  not  shrink  in  washing. 
They  are  non-absorbent,  and  rapidly  conduct  away  heat;  hence 
cotton  is  the  wrong  material  for  undergarments,  for  it  soaks  up 
the  perspiration  and  becomes  wet,  and  the  moisture  is  re-evapor- 
ated, causing  a  chill  to  the  surface  of  the  body.  The  heat  of 
the  body  is  not  retained  by  cotton,  but  is  rapidly  dissipated.  A 
material  called  "  cellular  "  cotton  cloth  obviates  the  last  defect. 
In  this  material  the  fibres  are  so  woven  as  to  form  cellular  air 
interspaces  in  the  texture.  Air  being  a  bad  conductor  of  heat, 
the  cellular  cloth  is  much  warmer  than  ordinary  cotton  clothing. 
Cotton  materials  are  preferable  to  woollen  for  the  outer  clothing  of 
sick  and  hospital  nurses,  as  organic  matters  in  the  air  cling  far  less 


Fig.   52. — Linen  Fibres  (x  about  200). 

easily  to  cotton  than  to  wool,  and  the  former  is  more  readily 
cleaned. 

Linen  materials  have  a  very  fine,  smooth,  and  close  texture. 
Under  the  miscroscope  the  fibres  of  linen  are  seen  to  be  cylindrical 
and  jointed,  with  minute  branching  filaments  at  intervals  (fig.  52). 
These  latter  are  the  elementary  fibres  of  which  the  main  fibre  is 
composed.  Linen  is,  like  cotton,  a  good  conductor  of  heat  and  a 
bad  absorbent  and  retainer  of  moisture,  and  is  an  unsuitable 
material  for  underclothing. 

Wool  forms  a  valuable  material  for  clothing.  Under  the 
microscope  the  fibres  (fig.  53)  are  seen  to  be  rounded,  colourless 
(unless  dyed),  with  fine  cross-markings  and  indentations  in  the 
border  at  the  site  of  the  cross-markings.     There  is  a  central 


3oS 


HYGIENE    AND    PUBLIC   HEALTH 


longitudinal  canal,  but  it  is  generally  obliterated.  The  cross- 
markings  and  reticulations  are  best  seen  in  new  wool,  as  when 
the  fibres  are  old  and  worn  they  are  not  so  distinct. 

Wool  is  an  extremely  bad  conductor  of  heat,  and  is  very 
absorbent  and  retentive  of  water  and  moisture,  hence  its  value 
as  a  material  for  underclothing.  Being  a  non-conductor,  wool  is 
warm  by  preventing  the  dissipation  of  the  bodily  heat.  Its  non- 
conducting properties  are  partly  due  to  the  wool  fibres  themselves, 
which  contain  an  animal  oil  in  their  substance,  and  partly  to 
the  air  entangled  in  their  interspaces.     After  exercise  causing 

perspiration,  the  moisture  is  ab- 
sorbed and  retained  by  the  wool, 
and  the  vapour  is  condensed,  thus 
giving  back  to  the  body  the  heat 
rendered  latent  by  evaporation 
from  the  surface  of  the  skin.  A 
woollen  garment  after  exercise  is 
therefore  warm  and  dry,  and  pre- 
vents the  chilling  of  the  surface 
from  the  lowering  of  the  tempera- 
ture by  evaporation,  which  is  so 
dangerous.  In  hot  climates  especi- 
ally, wool  should  be  worn  next  the 
skin  to  ward  off  those  chills  which  are  often  the  forerunners  of 
dysentery,  diarrhoea,  and  ague. 

The  disadvantages  of  wool  are  the  hardening  and  shrinkage 
the  fibres  undergo  when  frequently  washed  (especially  where  soda 
and  strong  soaps  are  used),  and  the  loss  of  absorbency  resulting 
therefrom.  The  wool  fibres,  being  hygroscopic,  readily  absorb 
organic  vapours  and  dirt  from  the  body,  so  that  woollen  under- 
garments require  frequent  but  careful  washing.  The}'  should  be 
washed  in  soft,  cold  or  tepid,  water,  with  mild  soap  without  soda, 
and  should  not  be  much  wrung  out.  Flannel,  which  is  a  woollen 
material,  is  also  often  found  to  be  too  irritating  to  be  worn  next 
to  a  delicate  skin. 

"  Flannelette  "  is  a  highly  inflammable  cotton  material,  which, 
on  account  of  its  warmth  and  cheapness,  has  been  largel}'  used. 
This  material  has  been  responsible  for  the  loss  of  many  lives  by 
burning,  and  as  a  consequence  much  of  it  now  sold  is  first  rendered 
non-inflammable ;  but  after  many  washings  the  previously  treated 
flannelette  returns  to  its  highly  inflammable  condition. 


Fig.  53. — Wool  Fibres 
(x  about  200). 


EXERCISE    AND    CLOTHING 


309 


The  addition  of  a  little  kerosene  or  paraffin  to  the  soap  used 
for  washing  clothes  facilitates  the  removal  of  dirt,  as  less  rubbing 
and  wringing  of  the  clothes  are  then  required;  but  the  clothes 
must  be  well  rinsed  after  the  washing  and  aired  out  of  doors, 
or  a  slight  odour  of  kerosene  (when  kerosene  soap  is  used)  )s 
retained  in  the  fabrics.  The  paraffin  soaps  are  free  from  this 
defect.  The  grease  and  dirt  cannot  be  removed  from  clothes 
(any  more  than  from  the  skin,  owing  to  the  fatty  secretion  from 
the  sebaceous  glands  at  the  roots  of  the  hair  follicles)  by  merel}' 
washing  in  water  without  the  use  of  soap.  The  alkali  of  the  soap 
combines  with  the  grease  and  emulsifies  it,  whereby  it  is  easilj' 
washed  off;  whilst  the  fatty  acid  prevents  the  too  great  removal 
of  the  oil  from  the  wool  fibres,  and  the  deterioration  of  the 
fabric.  Cheap  soaps,  containing  an  excess  of  alkali,  are  bad  for 
the  skin,  for  it  is  ren- 
dered over-dry  and 
loses  suppleness  by 
excessive  removal  of 
sebaceous  secretion ; 
and  they  are  also  in- 
jurious to  woollen 
fabrics  by  carrying 
away  the  animal  oil 
contained  in  the 
fibres. 

In     merino,    wool 
and  cotton  are    mixed  in   varying  proportions.       "  Shoddy  " 
is  old,  used  and  worked  up,  wool  and  cloth. 

Silk  (fig.  54)  is  a  bad  conductor  of  heat,  but  is  less  ab- 
sorbent than  wool.  It  presents  some  advantages  for  under- 
clothing, as  it  is  more  cleanly  and  shrinks  less  than  wool,  and 
is  less  irritating  to  the  skin;  but  it  cannot  hold  perspiration 
like  wool.  It  is  expensive,  and  is  less  durable  than  cotton  or 
merino. 

Leather  and  Waterproof  Material. — These  are  invaluable  for 
exposure  to  very  cold  bleak  winds  and  rain.  Leather  is  the  more 
suitable  for  very  cold  climates.  Being  impermeable,  they  are 
extremely  warm,  but  this  impermeability  prevents  the  ventila- 
tion and  renewal  of  the  layers  of  air  confined  under  the  clothing 
near  the  skin.  The  discomfort  that  arises  from  the  wearing  of 
waterproofs  in  warm  weather  is  well  known. 


Fig.   54. — Silk  Fibres  (x  about  200) 


310  HYGIENE    AND    PUBLIC    HEALTH 

In  hot  climates  the  outer  garments  should  be  white  or  grey 
in  colour  to  protect  from  the  direct  rays  of  the  sun. 

At  the  two  extremes  of  life — in  childhood  and  old  age — warmth 
of  covering  is  most  essential.  Children  lose  heat  rapidly  and 
are  liable  to  chill,  partly  because  the  circulation  being  rapid, 
more  blood  is  carried  in  a  given  time  to  the  superficial  vessels, 
and  more  heat  is  thus  radiated  from  the  surface  than  in  an  adult ; 
but  mainly  because  in  children  the  surface  of  the  body  is  larger 
in  proportion  to  its  bulk  or  contents  than  is  the  case  in  adults. 

Children  should  be  clothed  in  woollen  materials;  and  the  legs, 
arms,  neck,  and  chest  should  be  equally  protected  with  the  other 
parts  of  the  body. 

In  old  age  the  circulation  is  often  feeble  and  languid,  and  the 
functions  of  heat-production  and  regulation  are  less  efficiently 
performed  than  before  senile  decay  commenced.     Consequently, 

if  the  body  is  chilled,  the 
restoration  to  the  normal 
heat  is  slow,  and  the  vital 
functions  are  dangerously 
depressed. 

Aniline     dyes     are    now 
Fig.  55.— Hemp  Fibres  (x  about  200).     largely  used    for   colouring 

various  dress  materials  and 
undergarments,  such  as  stockings.  As  a  rule  the  dyes  used 
are  free  from  arsenic  ;  but  it  has  occasionally  happened 
that  eczematous  sores  have  been  produced  on  the  feet  and 
legs  by  wearing  dyed  stockings,  and  there  can  be  but  little 
doubt  that  the  sores  were  due  to  the  action  of  arsenic  on  the  skin 
when  the  feet  were  hot  and  damp. 

A  good  material  for  clothing  purposes  must  meet  the  following 
requirements : — 

1.  It  must  afford  proper  protection  to  the  body  against  cold 
and  heat,  so  as  to  assist  in  preserving  it  at  a  proper  uniform 
temperature  in  winter  and  summer  alike. 

2.  It  should  interfere  as  little  as  possible  with  the  natural 
functions  of  the  skin. 

3.  It  must  exert  no  irritating  or  poisonous  effects  upon  the  skin. 

4.  It  must  not  be  highly  inflammable. 

It  has  been  seen  that  clothing  is  warm  in  proportion  to  its 
capacity  for  retaining  the  natural  heat  of  the  body,  and,  therefore, 
the  materials  which  are  the  worst  conductors  arc  the  warmest. 
Arranged  in  the  order  of  their  warmth,  the  materials  in  common 


EXERCISE    AND    CLOTHING  3II 

use  arc:  Wool,  fur  and  down,  silk,  cotton,  and  linen.  But  it 
must  be  borne  in  mind  that  the  warmth  of  an  article  of  clothing 
also  depends  upon  certain  other  subsidiary  circumstances.  Thus 
the  colour  of  the  most  external  clothing  is  important,  black 
absorbing  more  of  the  heat  from  external  sources  than  any  other 
colour,  and  white  the  least  of  all.  The  order  in  which  the  dif- 
ferent colours  absorb  heat  is  as  follows: — Black,  dark  blue,  light 
blue,  dark  green,  turkey  red,  light  green,  dark  yellow,  pale 
straw,  and  white.  The  degree  of  porosity  of  the  article  also 
affects  its  warmth,  for  the  small  spaces  are  occupied  by  air, 
which  is  a  bad  conductor  of  heat;  flannel  is  the  most  porous 
article  of  clothing,  and  silk  is  the  least  porous.  Again,  the 
textile  fabrics  with  rough  surfaces  are  generally  warmer  than 
those  which  are  smooth,  the  rougher  surfaces  stimulating  the 
skin  and  favouring  the  capillary  circulation.  The  hygroscopic 
properties  of  the  material  determine  its  warmth  to  a  considerable 
degree,  for  this  property  of  absorbing  moisture  enables  the  fabric 
to  absorb  the  perspiration  from  the  skin;  and  the  chilling  effect 
of  the  evaporation  of  this  natural  moisture  is  thereby  trans- 
ferred from  the  skin  to  the  article  covering  it.  The  following 
is  the  order  in  which  the  various  articles  of  clothing  must  be 
placed,  so  as  to  indicate  their  relative  hygroscopic  properties: — 
Wool,  fur,  eider-down,  silk,  linen,  cotton.  The  same  order  will 
indicate  the  facility  with  which  each  material  absorbs  odours. 

A  few  general  remarks  may  next  be  made  upon  the  require- 
ments of  suitable  and  healthy  clothing.  The  clothing  of  the  body 
should  be  designed  for  the  following  purposes: — (i)  For  pre- 
serving the  whole  of  the  body  at  a  uniform  temperature.  Doubt- 
less the  dress  of  women  and  children  offends  chiefly  against  this 
requirement.  Women's  dress  encourages  a  very  unequal  distri- 
bution of  warmth;  the  upper  part  of  the  chest  and  the  legs  are 
unduly  exposed,  whereas  the  trunk  below  the  upper  part  of  the 
chest  is,  by  comparison,  clothed  very  warmly.  The  dangerous 
habit  of  exposing  the  bare  legs  and  arms  of  infants  to  the  vicissi- 
tudes of  our  winter  cHmate,  and  swaddling  the  rest  of  their  bodies 
with  many  layers  of  warm  clothing,  should  be  obvious  to  all. 
(2)  Clothing  must  interfere  with  no  natural  function  or  move- 
ment, so  as  to  lead  to  injury  of  the  part  of  the  body  to  which  it 
is  applied. 

The  head  covering  should  be  light,  porous  (so  as  to  admit  air), 
and  with  no  tight  rim  to  press  upon  the  scalp  and  interfere  with 
the  circulation  of  its  blood  supply,  which  is  a  cause  of  baldness. 


312  HYGIENE   AND    PUBLIC   HEALTH 

No  tight-fitting  article  should  be  worn  round  the  neck,  as  im- 
portant vessels  are  specially  liable  to  be  pressed  upon  in  that 
situation.  The  trunk  and  extremities  have  probably  suffered 
most  from  the  adoption  of  bad  principles  in  clothing;  and  the 
dress  of  women  in  many  respects  still  defeats  the  main  objects 
of  clothing.  Petticoats  and  dresses  are  often  heavy;  they 
impede  movement  and  accumulate  dirt,  and  they  exert  a  dragging 
weight  from  the  waist  and  hips.  They  should  either  be,  like 
the  male's  trousers,  suspended  by  braces,  or  hung  from  a  bodice 
by  means  of  buttons. 

The  effects  of  tight  lacing  are  to  deform  the  body  and  to  dis- 
place important  viscera.  The  diaphragm  is  pushed  up,  the  lung 
space  diminished,  and  the  lungs  and  heart  often  suffer  in  con- 
sequence. Constriction  and  displacement  of  the  liver  are  pro- 
duced, and  the  resulting  pressure  on  other  important  abdominal 
organs  causes  them  to  suffer  also.  Those  who  lace  tightly  are 
frequently,  therefore,  the  victims  of  dyspepsia,  malnutrition, 
gastralgia,  vomiting,  shortness  of  breath,  palpitation  and  faint- 
ness.  Tight,  rigid  corsets  give  rise  to  muscular  flabbiness,  which 
conduces  to  spinal  curvature,  round  shoulders,  and  a  stooping 
carriage.  The  waist  of  the  average  woman  should  be  from  26 
to  27  inches  in  circumference. 

Tight  sleeves  should  also  be  avoided.  Suspenders  should 
always  be  preferred  to  garters;  and  the  lower  extremities  of 
woman  should  be  protected  by  thicker  stockings  in  the  winter. 
The  substitution  of  warm  "  bloomers  "  for  the  petticoat  is  a 
practice  to  be  commended. 

With  reference  to  boots,  these  should  fit  the  foot,  and  at  the 
same  time  admit  of  free  movement.  The  natural  shape  of  the 
human  foot  is  that  of  a  fan — from  the  heel  to  the  toes.  The 
big  toe  should  be  in  a  straight  line  with  the  instep,  and  not  bent 
outwards  towards  the  other  toes.  Tight  or  badly  fitting  boots 
may  give  rise  to  fiat  foot,  ingrowing  toe  nails,  corns,  bunions, 
and  even  to  permanent  lameness.  The  soles  should  be  flexible 
and  the  heels  kept  low.  High  heels  cause  the  foot  to  press  for- 
ward in  the  boot,  tiring  the  walker  and  causing  a  feeling  of  dis- 
comfort. They  also  give  rise  to  an  uncertain  and  unbecoming  gait. 

In  conclusion,  it  may  be  said  that  clothing  should  not  be 
changed  according  to  calendar,  but  according  to  weather;  and 
that  clothing  worn  in  successive  layers  is  warmer  than  when  a 
similar  weight  of  material  is  applied  in  a  single  layer. 


CHAPTER  VHI 
FOOD,  BEVERAGES,  AND  CONDIMENTS 

Food. 

The  purposes  fulfilled  by  food  may  be  defined  to  be  as  follows: 

1.  To  form  new  tissues  in  the  process  of  growth. 

2.  To  repair  and  renew  the  wasted  tissues — solid  and  fluid — 
of  the  body. 

3.  To  provide  the  material  which  serves  as  fuel  to  the  body, 
and  which,  by  its  combination  with  oxygen,  is  reduced  to  the 
simpler  forms  of  urea,  carbonic  acid,  and  water,  thus  supplying 
the  sources  of  the  animal  heat  and  the  manifestations  of  energy 
which  are  essential  for  the  maintenance  of  life. 

All  the  various  food  substances  and  proximate  constituents  of 
food  may  be  classified  broadly  under  two  heads — as  nitrogenous 
and  non-nitrogenous. 

The  proteids,  which  are  substances  allied  in  chemical  constitu- 
tion to  albumin,  form  a  large  proportion  of  the  nitrogenous  food 
substances,  whilst  the  non-nitrogenous  substances  consist  of  the 
fats,  the  carbo-hydrates,  the  vegetable  acids,  the  mineral  salts, 
and  water. 

Proteins. — The  average  composition  of  proteins  or  albu- 
minoids may  be  taken  as  being  approximately  as  follows:  In 
100  parts — nitrogen,  16;  carbon,  54;  oxygen,  22;  hydrogen,  7; 
sulphur,  I.  The  proportion  of  nitrogen  to  carbon  is  nearly  in 
the  ratio  of  2  to  7.  In  the  group  headed  by  gelatine  (see  table) 
the  N  is  about  18  per  cent.,  and  the  proportion  of  nitrogen  to 
carbon  is  greater  than  in  albuminoids:  these  substances  are  much 
less  nutritious  than  the  albuminoids  proper.  In  the  process  of 
digestion  albuminoids  are  converted  into  albumoses  and  soluble 
peptones,  which  are  highly  diffusible  and  capable  of  passing 
through  the  inner  coats  of  the  alimentary  tract  into  the  blood 
and  lymph  streams.  A  part  of  the  peptones  is  further  trans- 
formed into  leucin  and  tyrosin,  but  the  final  products  derived 
from  proteid  food  are  carbonic  acid,  water,  and  urea.     Peptones 

313 


314 


HYGIENE  AND  PUBLIC  HEALTH 


differ  from  common  albumins  in  being  soluble,  uncoagulable  by 
heat,  acid,  or  spirit,  and  in  being  dialyzable. 


Non-Nitrogenous. 

Nitrogenous. 

, 

1 

Fats. 

Carbo- 
Hydrat  s. 

Vegetable 
Acids. 

Salts. 

1 

„  /"Albumin 

Olein 

Starch 

Oxalic 

Sodium  chloride 

^  1  Fibrin 

Stearin 

Dextrine 

Tartaric 

Potassium  chloride 

rg.s     Syntonin 

Palmitin 

Cane  sugar 

Citric 

Calcium  phosphate 

•S  g     Myosin 
^  ^     Globulin 

Margarin 
Butyrin 

Grape sugai 
Lactose    ^r 

Malic 
Acetic 

Magnesium  phosphate 
Iron,  etc. 

^  1  Casein 

Milk  sugar 

Lactic 

/"Gelatine 
.2:8     Ossein 

^ 

1^  g     Chondrin 
u,  VKeratine 

si 

«§/ Gluten 
^i  (Legumin 

■t;  /Kreatine 

<!>      1  Kreatin- 

|S-       ine 

[^  -S     Karnine 
{  Xanthine 

Nitrogenous  foods  are  essential  for  the  maintenance  of  animal 
life.  All  organized  animal  structures  contain  nitrogen,  and  there 
can  be  no  chemical  change  and  no  manifestation  of  energy  in  any 
animal  tissue  from  which  nitrogen  is  absent.  Consequently 
nitrogenous  foods  are  required  for  the  formation  of  new  and  the 
repair  and  renewal  of  old  tissues,  and  for  the  formation  of  the 
digestive  and  other  fluids  of  the  body.  The  nitrogenous  tissues 
of  the  body  are  also  the  regulators  of  the  absorption  and  vitiliza- 
tion  of  oxygen,  by  which  energy  is  manifested;  therefore  the 
proteid  foods,  which  make  and  repair  the  tissues,  also  participate 
in  this  regulation  of  oxidation  and  energy.  They  are  also  sup- 
posed to  have  another  function  under  certain  special  conditions, 
viz.,  the  formation  of  fat  and  the  yielding  of  energy;  but  of  this 
little  is  known,  and  doubtless  the  main  source  of  energy  is  the 
oxidation  of  non-nitrogenous  substances.  Under  a  diet  from 
which  nitrogen  is  withheld  the  body  languishes;  the  functions  are 
carried  on  at  the  expense  of  the  existing  tissues  and  structures, 
and  these  undergoing  no  renewal,  death  must  eventually  result. 


Foon  315 

The  albuminoids  proper  arc  of  nearly  equal  nutritive  value, 
and  are  therefore  mutually  replaceable  in  a  diet.  This  applies 
to  the  different  members  forming  the  animal  albuminoid  class 
and  to  the  vegetable  and  animal  albuminoids  taken  as  two 
separate  classes.  The  only  advantage — if,  indeed,  it  be  one  at 
all — ^in  favour  of  animal  nitrogenous  food  as  opposed  to  vegetable 
is  that  the  former  is  more  rapidly  and  completely  digested,  and 
therefore  more  quickly  replaces  wasted  tissue.  But  against  this 
must  be  set  the  fact  that  proteid  substances  are  split  up  in  the 
processes  of  healthy  digestion,  either  in  part  or  whole,  into 
metabolic  products,  which  are  potentially  poisonous  to  the 
system.  These  bodies  are,  no  doubt,  under  conditions  of  normal 
health  and  activity,  disposed  of  in  the  system  without  detriment 
to  its  vital  functions;  but  if  they  arc  produced  in  excess,  or  more 
rapidly  than  they  can  be  destroyed  or  eliminated,  as  may  happen 
after  a  meal  of  meat  excessive  in  amount,  they  tend  to  accumulate 
in  the  system,  and  may  be  the  cause  of  that  heaviness  and 
languor  so  frequently  experienced  by  large  meat  eaters,  especially 
by  those  of  a  dyspeptic  habit. 

The  Inflttence  of  Bacteria  on  the  Digestive  Processes. — The  part 
played  by  bacteria  in  the  digestive  processes  is  not  fully  under- 
stood, but  what  is  known  may  be  briefly  summarized.  Large 
numbers  of  organisms — chiefly  streptococci — are  contained  in 
the  secretions  of  the  mouth,  but  what  part  these  take  in  salivary- 
digestion  is  not  known.  Very  few  bacteria  are  normally  present 
in  the  stomach  and  duodenum,  the  acidity  of  the  gastric  juice  in 
health  being  unfavourable  to  the  growth  of  most  organisms,  and 
the  periodical  emptying  and  scouring  of  the  stomach  tending  to 
their  elimination.  If  the  stomach  is  dilated,  and  its  contents 
are  unduly  retained,  yeasts,  sarcinae,  and  other  organisms  tend 
to  multiply,  fermentation  ensues,  and  health  is  disturbed. 

In  the  small  intestine  bacterial  multiplication  increases  as 
the  caecum  is  approached.  The  action  of  the  bile  is  to  favour 
the  increase  of  B.  coli  and  allied  organisms,  whilst  streptococci 
and  B.  protens  are  restricted.  In  the  colon  the  bacterial  multi- 
plication is  greatly  increased,  owing  to  the  slowing  down  in  the 
rate  of  movement  of  the  intestinal  contents.  The  predominant 
organisms  here  are  the  members  of  the  B.  coli  group  and  strepto- 
cocci, B.  coli  being  usually  the  more  numerous  (Andrewes).  The 
conditions  in  the  large  intestine  are  very  largely  anaerobic,  owing 
to  the  absence  of  oxygen;  and.  in  consequence,  the  digested  food 


3l6  HYGIENE  AND  PUBLIC  HEALTH 

is  here  subjected  to  changes  of  a  far-reaching  nature,  proteins 
especially  being  broken  down  to  a  point  beyond  that  which  the 
body  demands  for  its  own  nutritional  needs,  and  certain  of  the 
products  which  thus  arise  are  actually  harmful  (Andrewes). 

These  metabolic  products  of  proteids,  when  soluble,  are  taken 
into  the  blood,  and  transported  to  the  liver.  Here  they  are 
transformed  into  substances  essential  for  the  nutrition  of  the 
body,  unless  present  in  too  large  an  amount  or  in  an  unsuitable 
form.  In  such  an  event  symptoms  of  alimentary  toxaemia  super- 
vene. It  seems  probable  that  the  thyroid  gland  is  also  con- 
cerned in  the  process  of  counteracting  the  injurious  effects  pro- 
duced by  circulation  in  the  blood  of  proteoses  and  bacterial 
toxins.  The  circumstances  favouring  alimentary  toxaemia  would 
appear  to  be,  therefore,  either  (i)  unsuitability  of  food,  (2)  de- 
fective conditions  in  the  small  or  large  intestine  or  both,  inducing 
an  excess  of  the  metabolized  products  of  proteids  in  the  food, 
which  are  poisonous  to  the  body  (indol,  skatol,  phenol,  cresol, 
etc.),  and  (3)  changes  in  the  liver,  which  prevent  its  performing 
its  proper  function  of  a  transformer  of  proteids.  It  has  been 
thought  by  some  that  stasis  of  the  intestinal  contents  in  the 
caecum  and  colon,  owing  to  mechanical  derangements  (adhesions, 
prolapses,  kinks,  dilatations,  and  contractures)  are  the  chief 
cause  of  the  production  of  toxic  products  in  the  bowels  from 
bacterial  fermentations. 

On  the  whole,  it  may  be  concluded  that  whilst  in  health  the 
bacterial  flora  of  the  lower  intestines  have  a  useful  effect  in 
breaking  down  proteid  residues  to  a  point  beyond  that  which 
can  be  exercised  by  the  ordinary  digestive  ferments  (enzymes), 
and  so  enabling  a  larger  proportion  of  proteid  material  to  be 
absorbed  from  the  bowel  than  would  otherwise  be  the  case,  still 
this  process  has  certain  drawbacks,  especially  the  undue  produc- 
tion by  anaerobic  organisms  of  soluble  toxic  products  in  excess 
of  the  capacity  of  the  liver,  kidneys,  and  ductless  glands  to 
render  harmless  to  the  body  generally.  There  is  at  present  a 
school  of  medical  opinion  which  is  inclined  to  regard  the  lower 
bowel  as  the  place  of  origin  of  many  of  the  chronic  disorders  which 
lead  to  chronic  invalidism,  premature  old  age,  and.  early  death. 

Whilst  there  is  not  sufficient  evidence  to  prove  that  vege- 
tarianism, so-called,  is  more  conducive  to  health  or  longevity  than 
a  mixed  diet,  there  can  be  but  little  doubt  that  the  wealthier 
classes  eat  too  largely  and  too  frequently  of  meat.     Excess  of 


FOOD  317 

nitrogenous  food  causes  not  only  an  abnormal  production  of  the 
poisonous  bodies,  of  whose  potentialities  for  evil  but  little  is 
at  present  known;  but  an  excess  of  nitrogenous  waste  accumu- 
lates in  the  blood,  oxidation  is  interfered  with,  the  liver,  the 
kidneys,  and  the  other  excretory  organs  are  overtaxed  in  their 
work  of  eliminating  waste  substances,  which  are  also  insufficiently 
elaborated,  and  gout,  or  liver  and  kidney  disease  result. 

As  gelatine,  ossein,  etc.,  are  not  the  nutritive  equals  of  the 
other  albuminoids,  they  cannot  replace  them.  Gelatine  is  easily 
oxidized  in  the  body,  and  appears  to  be  of  value  in  cases  of  acute 
disease,  when  given  in  the  form  of  jellies,  in  preventing  excessive 
tissue  waste.  In  such  cases  the  albuminoids,  if  given,  may  not  be 
digested  or  assimilated.  Gelatine  probably  cannot  form  nitro- 
genous tissues,  but  it  can  take  the  place  of  part  of  the  nitrogenous 
substances  in  the  blood  which  undergo  oxidation. 

The  extractives,  such  as  those  contained  in  the  juice  of  flesh, 
can  neither  build  up  tissue,  nor  serve  as  fuel,  but  they  appear  to 
act  as  regulators  and  stimulants  of  digestion  and  assimilation, 
especially  when  gelatine  and  allied  bodies  are  comprised  in  the 
diet.  Hence  the  use  of  beef-tea,  which,  as  usually  made,  contains 
little  beyond  extractives  in  the  dietary  of  sickness. 

Hydrocarbons  or  Fats. — These  bodies  are  compounds  of  glycerine 
with  the  fatty  acids — oleic,  stearic,  palmitic,  etc.  They  contain 
no  nitrogen,  but  are  made  up  of  carbon,  hydrogen,  and  oxygen, 
the  proportion  of  oxygen  being  less  than  sufficient  to  form  water 
with  the  hydrogen  present.  The  fats  are  unacted  upon  by  the 
saliva  and  by  the  gastric  juice,  and  pass  through  the  stomach 
unchanged;  but  in  the  small  intestine  they  are  emulsified  by  the 
pancreatic  juice  and  bile,  and  rendered  capable  of  absorption  by 
the  lacteal  vessels,  whilst  a  small  portion  is  saponified — i.e.,  split 
up  into  glycerine  and  fatty  acids,  the  latter  uniting  with  alkahes 
to  form  alkaUne  palmitates,  oleates,  and  stearates  (soaps),  which 
are  directly  absorbed  into  the  blood  or  lacteals. 

The  chief  function  of  the  fatty  foods  is  to  repair  and  renew 
the  fatty  tissues,  and  to  yield  energy  and  keep  up  the  animal  heat 
by  oxidation  into  carbonic  acid  and  water.  The  presence  of  the 
fats  in  food  promotes  the  flow  of  the  pancreatic  juice  and  bile; 
they  thus  help  in  the  proper  assimilation  of  other  foods,  and 
assist  the  excretory  functions  of  the  intestine,  which  are  badly 
performed  if  bile  and  the  other  digestive  fluids  are  not  secreted 
in  sufficient  quantity. 


3l8  HYGIENE    AND    PUBLIC   HEALTH 

The  animal  fats  are  more  easily  digested  and  absorbed  than 
the  vegetable.  If  there  is  excess  of  fat  in  a  diet,  it  passes  out 
unchanged  in  the  faeces. 

Carbo-hydrates. — These  substances  are  made  up  of  carbon, 
hydrogen,  and  oxygen,  the  oxygen  being  present  in  the  exact 
proportion  necessary  to  form  water  with  the  hydrogen  present. 
In  the  process  of  digestion  starch,  cane  sugar,  dextrine,  and  milk 
sugar  are  converted  into  grape  sugar.  This  change  is  commenced 
in  the  mouth,  during  the  process  of  mastication  of  the  food,  by 
the  action  of  the  saliva;  it  is  not  carried  any  further  in  the 
stomach,  but  is  completed  in  the  small  intestine  by  means  of  the 
pancreatic  juice.  The  starch  (CgHjoOg)  takes  up  a  molecule  of 
water  to  become  grape  sugar  (CgHjo^e)'  which  is  taken  up  by  the 
blood  and  carried  by  the  portal  vein  to  the  liver,  where  it  is 
deposited  as  glycogen  or  liver  starch.  The  liver  acts  as  a  store- 
house for  the  deposition  and  accumulation  of  these  converted 
starchy  foods,  which  are  subsequently  supplied  to  the  system  as 
the  needs  of  the  economy  demand,  there  to  undergo  oxidation 
for  the  manifestation  of  heat  and  energy,  and  to  be  used  for  the 
building  up  of  the  fatty  tissues  of  the  body. 

The  functions  of  the  starchy  foods  are  thus  seen  to  be  the  pro- 
duction of  animal  heat  and  energy  by  oxidation,  and  the  forma- 
tion of  new  fatty  tissues.  The  latter  property  has  been  demon- 
strated by  Lawes  and  Gilbert  by  experiments  in  the  fattening  of 
pigs.  The  fat  given  in  the  food  was  not  sufficient  to  account  for 
all  the  fat  stored  up  in  the  pigs.  Most  of  the  excess  must  have 
been  derived  from  the  conversion  of  the  carbo-hydrates,  but  a 
portion  may  have  been  due  to  the  metabolism  of  nitrogenous 
substances. 

The  fattening  caused  by  a  diet  rich  in  starch  and  sugar  ma}' 
partially  be  due  to  the  oxidation  of  these  substances  saving  the 
fatty  tissues  from  destruction,  and  allowing  the  fat  in  the  diet  to 
form  new  fatty  tissues. 

Although  the  functions  of  the  fats  and  carbo-hydrates  in  the 
economy  are  very  much  the  same,  they  are  not  mutually  replace- 
able under  ordinary  conditions,  if  health  and  vigour  are  to  be 
maintained  at  their  maximum.  Where  men  are  much  exposed 
to  very  cold  temperatures  and  undergo  great  fatigue  in  the  open 
air — as  during  Arctic  expeditions — a  diet  of  albuminoids,  fats, 
salts,  and  water  (without  carbo-hydrates)  may  maintain  them 
for  a  time  in  good  health;  but  the  deprivation  of  fat  from  the 


FOOD  319 

diet  under  any  circumstances  is  not  well  borne  and  leads  rapidly 
to  loss  of  health  and  vigour.  Moreover  fat  in  the  diet  stimulates 
the  flow  of  bile,  increases  intestinal  movements,  and  promotes  the 
passage  of  chyme  through  the  intestinal  mucous  membrane. 

The  absence  of  fat  in  a  diet  leads  to  a  state  of  malnutrition, 
possibly  predisposing  to  such  diseases  as  tubercle,  especially  in 
children  and  young  persons.  The  deprivation  of  starches  can 
be  borne  for  a  long  time  if  fat  is  given  ;  but  little  is  known  as  to 
the  ultimate  effects  of  such  deprivations,  for  wherever  food  can  be 
obtained  at  all,  the  starchy  constituents,  so  widespread  and 
abundant  in  Nature,  are  sure  to  be  largely  represented. 

It  also  appears  that  the  carbo-hydrates  are  concerned  with  the 
maintenance  of  the  proper  reactions  of  the  various  body  fluids 
(blood,  lymph,  gastric  juice,  urine,  etc.).  They  give  rise  to  lactic 
and  other  similar  acids  in  the  body,  which  act  upon  the  alkaline 
phosphates,  chlorides,  etc.,  and  elaborate  the  various  acid  juices 
characteristic  of  the  different  bodily  secretions  and  excretions. 
Starches  and  sugars  have  much  the  same  dietetic  value.  Cellu- 
lose is  only  to  a  slight  extent  converted  into  sugar  by  the  human 
digestive  processes,  consequently  much  passes  out  unchanged  in 
the  fsces. 

It  is  evident,  therefore,  that  a  diet  which  is  to  maintain  proper 
bodily  health  must  contain  all  the  three  substances — ^albuminoids, 
fats,  and  carbo-hydrates.  The  albuminoids  are  the  most  indis- 
pensable, as  without  them  vital  action  must  cease  for  want  of  a 
supply  of  nitrogen.  But  a  diet  of  albuminoids,  salts,  and  water, 
alone,  is  rapidly  destructive  of  healthy  action.  As  before  ex- 
plained, the  excessive  waste  resulting  from  the  metabolism  of  so 
much  nitrogenous  food,  necessary  to  maintain  animal  heat  and 
energy,  overtaxes  the  system,  and  imperfectly  oxidized  sub- 
stances accumulate  in  it,  which  pervert  healthy  action  and 
eventually  set  up  diseased  conditions. 

Organic  Acids. — These  exist  in  fresh  vegetables  and  fruit, 
probably  also  in  fresh  meat  and  milk,  in  combination  chiefly  with 
alkalies  as  alkaline  salts.  These  acids  form  carbonates  in  the 
system,  and  preserve  the  alkalinity  of  the  blood  and  other  fluids 
This  is  their  chief  function,  but  they  may  also  furnish  a  small 
amount  of  energy  and  animal  heat  by  oxidation.  If  these  sub- 
stances are  absent  in  a  diet,  the  blood  becomes  impoverished, 
and  scurvy  results.  There  is  evidence,  however,  that  fresh 
vegetables  or  lime  juice  are  not  alone  sufficient  for  the  preven- 


320  HYGIENE    AND    PUBLIC   HEALTH 

tion  or  the  cure  of  scurvy,  and  that  the  disease  may  be  due  to 
poisoning  by  the  ptomaines  of  tainted  animal  food,  or  by  bodies 
of  unknown  composition  present  at  times  in  tinned  or  preserved 
animal  foods,  which  are  apparently  in  good  condition  and  free 
from  putrefactive  taint. 

During  the  recent  voyage  of  The  Discovery  in  the  Antarctic 
regions,  symptoms  of  scurvy  appeared  when  the  crew  were 
receiving  tinned  preserved  foods  as  rations,  even  although  fresh 
meat  was  occasionally  eaten;  but  all  symptoms  of  scurvy  dis- 
appeared when  the  use  of  tinned  meats  was  abandoned,  and 
freshly  killed  meat  was  substituted.  It  seems  probable,  how- 
ever, from  the  most  recent  researches,  that  scurvy,  including 
infantile  scurvy  and  scurv3'-rickets,  is  due  to  the  absence  from, 
or  deficiency  in,  a  diet  of  a  certain  definite  body  of  unknown 
constitution,  which  has  well-defined  antiscorbutic  properties. 
Probably  very  small  amounts  of  these  accessory  antiscorbutic 
substances  only  are  necessary  to  supply  the  needs  of  the  or- 
ganism, and  they  are  certainly  not  present  in  all  foods,  even 
though  fresh.  They  are,  however,  present  in  fresh  milk,  meat, 
vegetables,  and  some  fruits. 

Scurvy,  although  formerly  very  fatal  to  crews  of  ships  on  long 
voyages,  and  to  populations  on  shore  during  times  of  want  and 
famine,  can  hardly  now  be  called  a  disease  of  modern  life,  when 
fresh  meat,  vegetables  and  fruit  are  within  the  reach  of  all 
classes.  Such  is  the  case  at  least  with  adults;  but  infants,  fed 
for  long  periods  exclusively  upon  condensed  milk  or  preserved 
foods,  have  been  shown  to  sometimes  suffer  from  a  form  of 
scurvy.  The  haemorrhages  characteristic  of  scurvy  take  place 
under  the  periosteum  of  the  long  bones.  The  disease  is  often 
associated  with  rickets  (hence  known  as  "  Scurvy  Rickets  "), 
and  is  generally  rapidly  cured  by  the  administration  of  fresh  milk 
and  fresh  food. 

The  mineral  salts  are  essential  for  the  growth  and  repair  of  all 
the  tissues  of  the  body.  The  phosphates  of  lime,  potash,  and 
magnesia  contribute  largely  to  the  formation  of  bone;  whilst 
iron  for  the  red  blood  corpuscles  and  colouring  matters,  chlorine 
for  the  gastric  juice,  potash  for  the  blood  cells  and  solid  tissues, 
and  soda  for  the  intercellular  fluids,  are  all  indispensable.  Mineral 
salts  are  required  in  diets  for  all  ages,  but  more  especially  for 
infants  and  children,  when  not  only  has  waste  to  be  made  good, 
but  new  material  for  the  growth  of  the  body  has  to  be  supplied. 


FOOD  321 

Water  is  a  component  part  of  all  the  so-called  solid  foods,  and 
is  likewise  taken  separately,  the  amount  of  water  contained  in 
the  solid  foods  of  an  average  diet  being  insufficient  for  the  needs 
of  the  body.  The  water  contained  in  different  food  stuffs  varies 
within  very  wide  limits;  in  some  articles  it  amounts  to  not  more 
than  12  per  cent,  by  weight,  while  in  others  it  may  exceed  90  per 
cent.  Water  is  necessary  to  make  up  the  losses  occasioned  by 
its  excretion  in  the  breath,  sweat,  urine,  and  faeces,  and  to  renew 
all  the  various  fluids  and  solid  organs  of  the  body,  into  whose 
constitution  water  largely  enters.  Water  also  serves  as  a  vehicle 
for  the  solution  and  dilution  of  the  solid  foods,  whereby  they  are 
more  easily  digested  and  assimilated,  and  it  is  essential  for  the 
elimination  of  many  waste  products. 

The  Digestibility  of  Food. — Not  very  much  is  known  of  the 
digestibility  of  different  kinds  of  food  under  varying  conditions, 
but  the  following  facts  have  been  ascertained: — The  protein  of 
the  ordinary  table  meats,  fish,  and  milk  is  very  readily  and 
completely  digested.  The  protein  of  vegetable  foods  is  much 
less  completely  digested  than  that  of  animal  foods.  As  much 
as  a  third  of  the  protein  of  beans,  for  instance,  may  escape 
digestion,  and  thus  be  useless  for  nourishment.  Much  of  the 
fats  of  animal  food  at  times  fails  to  be  digested.  The  carbo- 
hydrates of  vegetable  food,  with  the  exception  of  cellulose,  are  in 
general  very  digestible. 

Diet. 

From  physiological  experiment  and  actual  experience,  dietaries 
of  different  kinds,  suitable  for  an  adult  under  varying  conditions, 
have  been  constructed;  but  there  is  considerable  discrepancy 
among  physiologists  regarding  the  qualitative  and  quantitative 
composition  of  these  diets.  Thus,  there  is  a  subsistence  diet, 
calculated  as  sufficient  for  the  internal  mechanical  work  of  the 
body  alone;  a  diet  for  ordinary  work  (entailing  the  expenditure 
of  energy  equivalent  to  300  foot-tons  per  diem) ;  and  a  diet  for 
laborious  work  (450  to  500  foot-tons  daily) — all  suitable  for  a 
man  of  average  size  and  weight  (150  pounds).  The  table  on 
p.  322  is  compiled  from  the  researches  of  Playfair,  Moleschott, 
Pettenkofer,  Voit,  and  Ranke. 

The  quantities  specified  represent  dryfood.  Ordinarysolid  food 
contains  on  an  average  50  or  60  per  cent,  of  water,  so  that  the 
quantities  tabulated  must  be  rather  more  than  doubled  in  actual 
practice.     About  50  to  80  ounces  of  water  are  in  addition  taken 

21 


322 


HYGIENE    AND    PUBLIC    HEALTH 


into  the  system  daily  in  a  liquid  form,  the  quantity  depending 
upon  the  amount  of  exertion  undergone  and  the  temperature 
and  humidity  of  the  air.     Thus,  for  subsistence  a  man  requires 


Subsistence. 

Ordinary  Work. 
Oz.  a\ .      Grammes. 

4-5          127 

3-5           99 

I4-0         397 

i-o           28 

Laborious  Work. 
Oz.  av.     Grammes. 

6-5          184 

4-0          113 

17-0         482 

1-3            37 

Proteins  . 
Fats 

Carbo-hydrates 
Salts 

Oz.  av.     Grammes. 

2-0            57 

0-5            14 

1 2  -o         300 

0-5           14 

iS-o         38s 

Total  water -free  food 

23-0         651 

28-8         816 

about  xV  ounce  of  water-free  food  for  each  pound  of  body  weight, 
and  for  ordinary  work  about  i  ounce. 

By  the  following  table,  which  shows  the  approximate  percentage 
composition  of  some  of  the  more  ordinary  articles  of  food,  it  is 
possible  to  calculate  a  diet  consisting  of  some  of  these  common 
foods. 


In  100 

Parts. 

Proteins. 

Fats. 

Carbo- 
hydrates. 

Salts. 

Raw  meat 

20-5 

8-5 

1-5 

Hen's  eggs 

13-5 

II-5 

— 

I-o 

Cow's  milk 

4-0 

3-5 

4-S 

0-7 

Butter      . 

1-5 

83-.S 

I-o 

1-5 

Cheese 

28'0 

23-0 

I'D 

7-0 

Bread 

8-0 

0-5 

50-0 

1-5 

Potatoes  . 

2'0 

O'l 

21'0 

I-o 

Oatmeal  . 

12-6 

5-5 

63-0 

3-0 

Supposing  a  diet  of  meat,  bread,  and  butter  is  required  for  a  body  of 
nien  in  ordinary  work. 

Let  Ar=amount  of  meat  required  in  ounces  per  head,  per  diem. 

}'=amount  of  bread 

^:= amount  of  butter 

Then x  H y  H ^  z  provides  4-5  oz.  (proteins). 

100  100  100  J  \r  I 

— -  X  -h  — -  y  H ^'  z  provides  3-5  oz.  (fats). 

100  100  100      ^  '^  -^  ^        ' 

- —  y  -I z  provides  14  ozs.  (carbo-hydrates). 

100  100  ■'  ' 

These  equations,  when  solved,  give  the  required  amount  of 
meat  as  io-8  ounces,  the  bread  as  28  ounces,  and  the  butter  as 
about  3  ounces. 


DIET  323 

The  amount  of  nitrogen  in  the  diet  for  ordinary  work  is  315 
grains  (20-4  grammes),  and  the  amount  of  carbon  4,790  grains 
(310-4  grammes).  One-tenth  of  the  total  nitrogen  ehminated 
leaves  the  body  in  the  fseces;  the  kidneys  eliminate  the  remainder 
chiefly  in  the  form  of  urea;  the  skin  and  lungs  give  off  only  a 
trace  in  the  form  of  ammonia. 

Albumin  contains  16  per  cent,  by  weight  of  nitrogen  and  48-4 
per  cent,  of  carbon.  Fat  contains  76-8  per  cent,  of  carbon,  and 
carbo-hydrates  about  43  per  cent,  of  carbon. 

In  the  best  diets  the  proportion  of  nitrogen  to  carbon  should  be 
about  as  i  to  15. 

The  energy  obtainable  from  the  different  articles  of  food  is 
expressed  as  so  many  foot-tons  per  ounce  consumed.  It  is  the 
amount  which  would  be  produced  theoretically,  if  the  constituents 
of  the  food  were  completely  oxidized  to  carbonic  acid  and  water; 
and  the  energy  derivable  on  this  hypothesis  from  different  food 
stuffs  can  be  calculated  from  the  heat — as  measured  in  a  calori- 
meter— -required  for  their  complete  combustign.  It  is  evident, 
however,  that  such  theoretical  expressions  may  have  a  limited 
bearing  upon  dietetic  value,  which  depends  so  largely  upon 
the  digestibility  and  capability  of  assimilation  of  different 
food  products;  and  that  the  whole  of  the  potential  energy 
thus  calculated  is  therefore  not  available.  In  the  case  of 
albuminoids  also,  a  portion  passes  out  of  the  animal  system 
incompletely  oxidized  in  the  form  of  urea.  The  figures  usually 
given  are: 

One  ounce  of  dry  protein  yields  173  foot-tons  of  potential 
energy. 

One  ounce  of  fat  yields  378  foot-tons  of  potential  energy. 

One  ounce  of  dry  carbo-hydrate  yields  135  foot-tons  of  potential 
energy. 

According  to  these  figures,  the  average  daily  diet  for  ordinary 
work  would  yield  3,977-5  foot-tons,  or  in  round  numbers  close 
upon  4,000  foot-tons;  but  a  large  proportion  of  this  total  energy, 
viz.,  about  2,500  foot-tons,  is  devoted  to  the  maintenance  of  the 
body  temperature,  and  to  the  performance  of  the  various  bodily 
functions,  when  the  body  is  in  a  state  of  rest. 

In  a  state  of  rest,  a  man  of  150  pounds  weight  gives  off  about 
16  cubic  feet  of  COg  gas  in  twenty-four  hours.  The  production 
of  I  cubic  foot  of  CO2  by  combustion  is  equivalent  to  160  foot- 
tons  of  energy.     Therefore  16x160=2,560  foot- tons  of  energy 


324  HYGIENE   AND    PUBLIC   HEALTH 

are  consumed  in  the  production  of  the  i6  cubic  feet  of  CO 

daily. 

Again,  if  the  average  temperature  of  the  air  is  taken  as  50°  F., 

the   difference  between   the  temperature  of  the   human   body 

(98°  F.)  and  that  of  the  air  is  48°  F.     If,  then,  we  consider  the 

human  body  as  absorbing  and  losing  heat  like  water,  the  energy 

required  to  support  a  temperature  of  98°  F.  in  a  man  of  150 

pounds  weight  is 

150  X  48  X  775 

=  2,490  foot-tons. 

2,240  ^ 

The     number     775    is    Joule's    equivalent,    i.e.,    the    number 

of    foot-pounds    of    energy    necessary   to    raise    i    pound   of 

water  1°  F. 

These  two  methods  of  estimating  the  amount  of  energy  neces- 
sary to  sustain  human  life  are  seen  to  produce  very  similar  results, 
viz.,  2,560  foot-tons  in  one  case,  and  2,490  foot-tons  in  the  other. 
The  subsistence  diet  given  in  the  table  (p.  322)  yields  2,155  foot- 
tons  of  theoretical  energy.  Playf air's  subsistence  diet  (2-5  oz. 
protein,  i  oz.  fat,  12  oz.  carb.-hyd.),  however,  yields  2,430  foot- 
tons  of  theoretical  energy,  which  is  nearly  identical  with  the 
results  of  the  two  methods  just  described. 

The  average  diet,  as  before  said,  jdelds  nearly  4,000  foot-tons 
of  theoretical  energy.  If  300  foot-tons  is  taken  as  the  energy 
consumed  in  actual  physical  labour,  then  4,000  —  300=3,700 
foot-tons  are  consumed  in  supplying  energy  for  the  functions 
of  the  body  in  a  state  of  physical  activity.  This  would  mean 
that  during  ordinary  work  the  production  of  COg  is  raised  from 
16  cubic  feet  to  an  average  of  23  cubic  feet  in  the  24  hours;  or 
supposing  the  man  works  for  8  hours  and  rests  for  16  hours, 
then  the  CO^^'produced  in  the  8  hours  of  work  is  11 -8  cubic 
feet  (1-47  cubic  feet  per  hour),  and  in  the  16  hours  of  rest  ii-2 
cubic  feet  (0-7  cubic  foot  per  hour).  In  the  same  way  the  diet 
for  hard  (laborious)  work  produces  4,930  foot-tons  of  energy: 
subtracting  500  for  actual  visible  work,  there  is  left  4,430  foot- 
tons  for  the  work  of  the  body,  equivalent  to  the  production  of 
27- 6  cubic  feet  of  CO^  in  24  hours,  or  i-6  cubic  feet  per  hour  for 
12  hours  of  work,  and  07  per  hour  for  12  hours  of  rest. 

The  theoretical  amounts  of  heat  produced  by  the  metabolism 
of  various  foods  within  the  body  have  been  calculated,  and  are 
stated  in  terms  of  calories — a  calorie  being  the  amount  of  heat 
required  to  raise  a  kilo  (or  i  litre)  of  water  1°  C,  or,  which  is  the 


DIET  325 

same  thing,  i  pountl  of  water  4°  F.     In  these  calculations  allow- 
ance IS  made  for  incompletely  oxidized  products. 

The  heat  value,  or  amount  of  energy  set  free  in  combining  with 
oxygen,  of  i  ounce  of  each  of  the  three  chief  nutritive  constituents 
of  food,  when  metabolized  within  the  body,  is  as  follows: — 

Proteins  .....      116  calories. 

Carbo-hydrates  .  .  .  .  .     116       ,, 

Fat  ......     263 

According  to  this  table,  the  diet  for  ordinary  work  yields  the 
following : — 


Oz.  av.                 Grammes. 

Calories. 

Proteins          ....               4';                    127 

Fats 3-5                     99 

Carbo-hydrates       .          .          .             i4'0          ,          397 

522 

921 

1,624 

22-0             i             623 

i 

3.067 

In  applying  the  calorie  standard  to  any  particular  kind  of  food, 
it  is  merely  necessary  to  multiply  the  percentage  (in  grammes) 
of  proteid  or  carbo-hydrate  which  it  contains  by  4-1,  and  the 
percentage  of  fat  by  9-3,  to  obtain  the  total  calories  yielded  by 
100  grammes  of  the  food. 

The  fuel  value  of  Voit's  standard  diet  for  the  average  man 
doing  moderate  work  is  3,050  calories.  In  America,  the  Atwater 
standard  is  the  one  usually  accepted.  This  places  the  daily 
protein  requirement  at  125  grammes,  with  sufficient  fat  and 
carbo-hydrates  to  yield  3,500  calories. 

Professor  Chittenden  of  Yale  University,  in  his  work  on  Physio- 
logical Economy  in  Nutrition  with  Special  Reference  to  the 
Minimal  Proteid  Requirements  of  the  Healthy  Man,  has  shown 
that  health  and  vigour  without  loss  of  body  weight,  when 
equilibrium  has  once  been  established,  can  be  maintained  on  a 
diet  containing  only  from  one-third  to  one-half  of  the  proteid 
stated  to  be  necessary  in  the  standard  dietary  scales  of  Voit, 
Ranke,  Moleschott,  and  other  authorities,  which  have  received 
almost  universal  acceptance,  and  this  without  any  increase 
and,  even  in  some  cases,  with  a  diminution  in  the  non-nitrogenous 
elements  of  the  diet.  The  experimental  diets  (Chittenden's) 
were  "  mixed,"  and  not  purely  vegetarian,  but  meat  was  only 
sparingly  taken. 


326  HYGIENE    AND    PUBLIC    HEALTH 

Chittenden's  experiments  were  conducted  over  a  period  lasting 
some  months  with  3  classes  of  men,  namely  (A)  brain-workers, 
consisting  of  5  professional  men;  {B)  a  detail  of  13  U.S.A. 
soldiers,  representative  of  men  undergoing  moderate  physical 
work;  and  (C)  a  group  of  8  University  students,  all  being 
thoroughly  trained  athletes,  and  engaged  daily  in  arduous 
physical  exercises. 

Voit's  standard  diet  for  ordinary  work  for  an  adult  man  of 
average  body  weight  (70-75  kilos  =  154-165  lbs.)  requires  daily 
118  grammes  (=  4-16  oz.)  of  proteid  or  albuminous  food,  of  which 
105  grammes  should  be  absorbable,  56  grammes  (=1-98  oz.)  of 
fat,  and  500  grammes  (=  17-65  oz.)  of  carbo-hydrate,  with  a  total 
fuel  value  of  over  3,000  calories,  in  order  to  maintain  the  body 
in  equihbrium.  This  diet  contains  the  equivalent  of  at  least 
16  grammes  of  nitrogen. 

Chittenden's  experiments  with  class  A  show  that  during 
periods  ranging  from  6  to  18  months,  these  men  maintained 
their  body  weight  (in  some  cases  there  was  an  initial  loss), 
estabhshed  nitrogen  equilibrium,  kept  in  good  health,  and  pur- 
sued their  ordinary  avocations  with  an  average  daily  metabolism 
of  from  5-4  to  8-9  grammes  of  nitrogen;  that  is  to  say,  with  diets 
containing  only  from  34  to  56  per  cent,  of  the  proteids  considered 
essential  by  Voit,  whilst  the  total  fuel  values  of  their  diets  varied 
from  2,000  to  2,500  calories,  as  against  the  3,000  of  Voit's 
scale. 

The  soldiers  in  class  B  during  a  period  of  5  months  were 
on  diets  containing  only  from  44  to  50  per  cent,  of  the  proteids 
in  Voit's  diet,  and  with  total  fuel  values  of  2,500  to  2,800  calories. 
These  men  maintained  their  body  weights,  and  established  con- 
ditions of  nitrogenous  equilibrium,  whilst  their  physical  condi- 
tion was  markedly  improved  during  the  period  of  the  experi- 
ment, which  also  coincided  with  a  period  of  physical  training  and 
gymnastic  work. 

With  the  athletes  in  class  C  the  same  results  were  obtained, 
the  average  amount  of  proteid  in  their  diets  being  about  55  per 
cent,  of  Voit's  scale,  and  the  fuel  values  varying  between  2,000 
and  3,000  calories.  All  these  men  well  maintained  for  the 
whole  period  of  experiment  their  physical  condition,  and  were 
just  as  "  fit  "  as  prior  to  commencing  their  reduced  dietaries, 
when  there  was  an  average  daily  metabolism  of  over  120 
grammes  of  proteid,  these  athletes  having  been  firm  believers 


DIET  327 

in  the  necessity  for  an  abundance  of  proteid  food  (meat)  when 
training. 

Professor  Chittenden's  work  not  only  raises  the  question  as 
to  the  necessity  for  a  revision  of  the  accepted  dietary  scales, 
which  serve  as  standards  for  computing  the  daily  necessary 
food  for  soldiers,  sailors,  prisoners,  and  the  inmates  of  many 
different  kinds  of  institutions,  but  is  suggestive  of  the  hygienic 
possibilities  of  the  diet  of  reduced  proteid  value  as  a  matter  of 
general  apphcation.  If  the  amount  of  proteid  food  needed 
daily  for  the  actual  physiological  wants  of  the  body  is  not  more 
than  one-third  to  one-half  that  ordinarily  consumed  by  the 
average  individual,  as  Professor  Chittenden's  experiments  appear 
to  demonstrate,  not  only  is  there  waste  and  loss  of  energy  from 
the  vital  forces  being  engaged  in  the  metaboHsm  of  matter  which 
is  not  required,  and  is  of  no  service  to  the  body,  but  there  is 
also  the  danger  of  the  accumulation  in,  and  imperfect  removal 
of  such  waste  products  from  the  system;  and  even  if,  for  a 
time,  these  waste  products  are  properly  removed,  excessive  meta- 
bolism implies  greater  efforts  on  the  part  of  the  excretory  organs 
than  would  be  needed  under  a  diet  suited  to  the  exact  physio- 
logical needs  of  the  body. 

Overaction  of  the  liver,  kidneys,  and  other  excretory  organs, 
persisting  with  little  variation  over  long  periods  of  time,  and 
the  resulting  retention  of  partly  elaborated  and  toxic  waste 
matters  in  the  blood,  when  the  excretory  organs  are  unequal 
to  the  strain  put  upon  them,  furnish  the  conditions  which  are 
known  to  be  causative  of  degenerative  changes  in  the  tissues, 
and  which  lead  in  middle  life  to  many  chronic  diseases  of 
important  organs,  and  to  death  at  an  age  when  impairment  of 
functional  activity  should  hardly  have  commenced. 

Professor  Chittenden's  conclusions  have  been  by  no  means 
universally  accepted  by  physiologists  and  others  interested  in 
the  construction  of  dietary  scales,  as  they  seem  opposed  to  the 
general  experience  of  civilized  nations;  and  however  interesting 
as  indications  of  the  adaptability  of  the  human  frame  and 
functions  to  alterations  in  nutrition  for  comparatively  short 
periods,  the  experiments  were  hardly  of  sufficiently  long  dura- 
tion to  warrant  conclusions  applicable  to  the  life  of  a  community 
for  long  periods  There  are  some  also  who  think  that  a  diet 
somewhat  in  excess  of  actual  corporeal  needs  supplies  a  reserve 
of  energy,  which  may  be  useful  to  prevent  invasion  of  the  system 


328  HYGIENE    AND    PUBLIC   HEALTH 

by  the  agents  of  infection,  and  to  aid  the  restorative  powers 
of  the  body  in  the  case  of  actual  sickness.  The  whole  question 
of  the  adequacy  of  Chittenden's  dietary  scales  under  the  many 
varying  circumstances  of  mental  and  physical  activity  must, 
therefore,  be  still  considered  as  sub  judice. 

When  food  is  taken  in  large  excess  of  the  requirements  of  the 
system,  a  considerable  portion  remains  undigested;  fermenta- 
tive and  putrefactive  changes  are  set  up  in  the  undigested  mass 
as  a  result  of  the  activity  of  the  bacterial  organisms  always 
present  in  the  intestinal  canal,  foetid  gases  containing  sulphur 
and  carbon  are  formed,  and  dyspepsia  and  diarrhoea  are  pro- 
voked. Some  of  the  products  of  putrefaction  are  absorbed  into 
the  blood,  and  cause  fever,  torpor,  headache,  and  foetid  breath. 
Excess  of  fats  and  starches  tends  to  produce  acidity  and  flatulence ; 
whilst  taken  habitually  in  excess  they  may  cause  excessive  forma- 
tion of  fatty  tissues  and  obesity.  In  cases  of  over-eating  and 
faulty  digestion,  undigested  muscular  fibres,  fat,  and  starch  cells 
may  be  found  by  microscopical  examination  in  the  faeces  to  an 
unusual  extent,  and  occasionally  albumin  and  sugar  will  be  found 
in  the  urine. 

Deficiency  in  all  the  constituents  of  a  diet  tends  to  produce 
loss  of  weight,  debiUty,  prostration,  and  anaemia.  If  carried 
to  the  point  of  starvation,  low  fever  and  gastric  disturbances 
are  often  excited,  ending  eventually  in  death.  It  appears, 
however,  that  some  constitutions  can  withstand  long  periods 
of  fasting  (thirty  to  forty  days),  if  plenty  of  water  is  taken; 
apparent  health  being  maintained  the  whole  time,  although  with 
gradually  increasing  emaciation  and  debility.  The  elimination 
of  urea  is  always  markedly  diminished. 

The  considerations  which  will  influence  the  selection  of  a  diet 
are  many.  They  may  be  briefly  summarized  as  follows:  (i)  Age. 
It  is  generally  held  that  a  child  of  ten  requires  half  as  much, 
and  a  child  of  fourteen  quite  as  much,  as  a  woman.  An 
average  diet  for  a  child  between  eight  and  fourteen  years  of  age 
should  contain  about  6  ounces  of  meat,  14  ounces  of  bread,  6 
ounces  of  potatoes,  9  ounces  of  milk,  and  small  quantities  of 
butter,  fresh  vegetables,  tea  or  coflfee.  A  generous  diet  for  a 
working  man  would  contain  9  ounces  of  meat,  18  ounces  of  bread, 
16  ounces  of  potatoes,  16  ounces  of  milk,  2  ounces  of  butter  or 
dripping,  and  3  ounces  of  oatmeal.  Old  people  should  be  given 
somewhat  less  proteid   (about   15  per  cent,   less)   and  carbo- 


FEEDING    OF   INFANTS  329 

hydrates,  and  slightly  more  fat,  than  those  in  middle  life.  (J  Sex. 
Women  require  on  an  average  one-eighth  less  food  than  men. 

(3)  Selection  of  food.  In  making  the  selection,  the  local  market 
will  have  to  be  studied;  and  it  is  essential  to  furnish  a  sufficient 
variety  of  food.  The  digestibility  of  various  articles  of  foods 
must  also  be  taken  into  account.  On  an  average,  about  5  to 
10   per  cent,   of   all   the   common   food  stuffs    is    indigestible. 

(4)  What  is  of  prime  importance  is  to  see  that  the  dietary 
allotted  to  each  day  contains  the  proper  amounts  and  relative 
proportions  of  albuminoids,  fats  and  carbo-hydrates;  what- 
ever the  food  selected,  the  salts  will  always  be  in  sufficient 
quantity.  In  distributing  meat  rations  it  must  be  borne  in 
mind  that  20  per  cent,  of  the  gross  weight  must  be  deducted 
for  bone.  As  to  (5)  meals,  it  is  the  usual  practice  to  provide 
four  meals  daily:  breakfast,  dinner,  tea,  and  supper — at  intervals 
of  about  four  hours,  although  three  meals  a  day  are  sufficient 

for  an  adult. 

The  Feeding  of  Infants. 

Until  the  child  is  at  least  seven  months  old  nothing  but  milk  should  be 
given,  for  it  is  unable  to  digest  starch  and  other  foods.  The  following 
instructions  may  be  advantageously  followed,  at  the  earlier  ages  in  cases 
where  the  mother  is  unable  to  suckle  her  infant,  and  at  the  later  ages  in  all 
cases : — ^ 

(a)  During  the  first  six  weeks  after  birth  the  child  should  be  fed  every 
two  hours  throughout  the  day,  reckoned  as  between  4  a.m.  and  10  p.m., 
and  once  between  these  hours  in  the  night.  Its  food  should  consist  of  one 
part  of  fresh  cow's  milk  and  two  parts  of  water,  mixed  and  (if  there  is  any 
doubt  as  to  the  quality  of  the  milk)  boiled,  and  then  sweetened  with  a 
teaspoonful  of  brown  sugar  to  each  pint  of  the  mixture.  Barley  water 
may  sometimes  with  advantage  be  used  instead  of  plain  water,  but  lime- 
water  is  better  avoided.  The  mixture  should  be  kept  in  a  clean,  covered 
vessel,  and  in  a  clean,  cool  place,  between  meals.  The  temperature  of  the 
food  given  to  a  young  child  should  be  about  that  of  the  human  hand. 
Three  or  four  tablespoonfuls  should  be  given  to  a  child  each  time  it  is  fed. 

{h)  From  the  age  of  six  weeks  to  three  months  the  child  should  be  fed 
with  a  mixture  of  equal  quantities  of  cow's  milk  and  water,  wdth  sugar  as 
above ;  but  two  teaspoonfuls  of  cream  may  now  be  advantageously  added 
to  each  nreal.  The  quantity  given  at  each  meal  should  be  about  eight 
tablespoonfuls.  The  intervals  between  meals  should  now  be  gradually 
lengthened. 

(c)  From  the  age  of  three  months  to  seven  months  the  child  should  have 
a  mixture  of  two  parts  of  cow's  milk  to  one  of  water.  About  eight  table- 
spoonfuls should  at  first  be  given  at  each  meal,  but  the  intervals  between 
meals  being  still  lengthened,  a  larger  quantity  than  this  will  soon  be 
required.  The  quantity  of  cream  given  with  each  meal  may  now  be 
increased  from  two  to  three  or  four  tablespoonfuls.  The  infant  should 
only  be  fed  during  the  night  if  it  happens  to  awake. 

1  For  the  preparation  of  humanized  milk  from  cow's  milk,  see  page  376. 


330  HYGIENE    AND    PUBLIC   HEALTH 

The  following  is  a  useful  working  rule  for  the  feeding  of  a  child  during 
the  period  in  which  liquids  should  be  exclusively  given : — Begin  with  about 
thirty-two  tablespoonfuls  a  day,  as  above  (a),  and  increase  this  by  the 
addition  of  two  to  four  tablespoonfuls  a  week  up  to  the  end  of  the  seventh 
month. 

(d)  From  the  age  of  seven  months  to  twelve  months,  the  child  should  be 
fed  every  three  hours,  between  6  or  7  a.m.  and  9  or  10  p.m.  Each  meal 
should  consist  at  the  first  of  about  ten  to  twelve  tablespoonfuls  of  undiluted 
cow's  milk,  with  cream  as  above  (c) ;  but  three  of  the  meals  may  also  each 
contain  about  a  teaspoonful  or  more  of  baked  flour  or  arrowroot,  or  of 
some  infant's  food,  well  boiled  and  stirred  up  with  the  milk. 

(e)  From  the  age  of  twelve  months  to  eighteen  months  the  child  should 
still  be  fed  about  every  three  hours,  between  early  morning  and  night. 
The  amount  of  milk  should  be  about  twice  as  great  as  that  given  under  (d) ; 
and  porridge,  bread  and  milk,  bread  and  gravy,  bread  and  butter,  and  a 
lightly  boiled  egg  occasionally,  may  be  given  with  advantage,  or  in  place  of 
some  of  the  milk,  as  time  goes  on. 

When  nine  or  ten  months  old,  the  child  should,  as  a  rule,  be  gradually 
weaned,  but  it  is  well  not  to  commence  in  very  hot  weather,  owing  to  the 
risk  of  summer  diarrhosa. 

Feeding  bottles  should  be  boat-shaped,  preferably  with  an  opening  at 
each  end.  They  should  be  fitted  with  a  short  rubber  teat,  capable  of  being 
easily  turned  inside  out  for  cleaning.  The  long  feeding  tube  usually  found 
in  use  very  quickly  becomes  foul,  and  should  not  be  employed.  Any  milk 
left  in  a  feeding  bottle  after  a  meal  should  be  at  once  emptied  away.  Two 
bottles  should  be  used  alternately,  each  bottle  being  boiled  and  rinsed 
immediately  after  use,  and  placed  neck  downwards  to  drain  in  a  cool,  clean 
place,  so  that  no  dust  may  get  into  it.  Condensed  milk  is  never  so  good  for 
infants  as  fresh  milk;  if  used  at  all,  it  should  be  condensed  "  whole  "  milk. 
Condensed  nailk  should  never  be  given  to  an  infant  from  a  tin  which  has 
the  words  "  hand  skimmed  "  or  "  machine  skimmed  "  upon  the  label,  for 
such  milk  has  been  robbed  of  a  very  important  nutriment,  and  a  child 
cannot  thrive  on  it,  however  much  is  taken. 

It  is  harmful  to  give  children  tea,  beer,  spirits,  or  cheese,  for  they  inter- 
fere with  the  power  of  digestion;  and  teething  powders  or  soothing  syrups 
are  dangerous  because  they  often  contain  opium. 

When  an  infant  is  fretful  or  suffering  from  indigestion  or  diarrhoea,  it 
will  often  be  found  that  it  is  having  too  much  or  too  strong  food,  and  is 
fed  too  frequently.  By  diminishing  its  diet  or  diluting  the  milk  with  a 
little  extra  water,  and  carefully  attending  to  the  proper  feeding  times,  the 
child  will  often  get  well.  If,  in  spite  of  every  care,  it  continues  so  to  suffer, 
proper  medical  advice  should  always  be  sought. 

Relatively  too  much  starchy  food  along  with  too  little  fat  is  ascribed  as 
a  cause  of  rickets  in  young  children. 

Dr.  Reid  has  demonstrated  statistically  the  evil  that  results 
from  the  prevailing  practice  in  many  manufacturing  towns  of 
mothers  leaving  their  homes  during  the  day  to  work  in  factories. 
Children  are  as  a  consequence  deprived  of  their  natural  food  and 
of  the  care  of  their  natural  guardians.  An  inquiry  instituted  by 
1  Parliamentary  Bills  Committee  tended  to  show  that  the  amount 
of  infant  mortality  attributable  to  the  practice  of  married  women 
engaging  in  factory  work,  may  amount  to  21  per  cent,  of  the 


FEEDING   OF   INFANTS  331 

total.  Two  remedies  are  suggested  in  the  report,  one  being 
the  extension  of  the  period  of  compulsory  absence  from  work 
after  confinement,  required  by  the  Factory  Act,  1901,  from  one 
month  to  three;  and  the  other,  the  establishment  of  day  nurseries 
or  creches  by  local  authorities,  for  which  a  small  payment  should 
be  exacted  from  the  parents. 

Under  the  conditions  of  modern  urban  life  many  women  of 
the  poorer  classes  must  be  engaged  in  other  than  domestic 
labour,  and  absent  from  their  homes  for  many  hours;  and  the 
wage  earned  b)'  these  expectant  and  young  mothers  is  doubtless 
of  considerable  value  to  the  health  of  both  mother  and  child 
in  the  food  which  it  provides;  and  the  disadvantages  of  such 
work  at  such  times  is  therefore  to  some  extent  compensated 
for.  This  circumstance  has  to  be  borne  in  mind  in  connection 
with  the  suggestion  of  the  prohibition  of  the  employment  of 
women  within  four  weeks  of  confinement.  For  such  women 
a  cheap  and  well-administered  creche  is  a  great  boon;  and  it 
has  been  suggested  that  such  institutions  might  be  utilized  by 
the  elder  school  girls  for  training  purposes  in  the  management 
of  infants. 

The  advantages  of  a  creche  are  that  it  affords  a  healthy 
abode  for  the  infants  during  the  absence  of  their  parents  from 
home,  skilled  feeding  for  the  infants,  and  facilities  for  detecting 
the  onset  of  illnesses  when  the  creche  is  under  skilled  supervision. 
The  obvious  drawbacks  are  that  the  child  is  exposed  to  cold 
while  bringing  it  to  the  creche  and  taking  it  away  at  night,  and  the 
risk  of  the  spread  of  communicable  diseases  among  the  children. 

Homes  for  the  reception  of  pregnant  working  women  have 
been  for  some  years  in  existence  in  France.  The  experience  of 
these  homes  show  that  cessation  from  labour  for  a  fortnight  or  a 
month  preceding  confinement,  renders  the  pregnancy  more  likely 
to  proceed  to  the  normal  term,  and  the  infants  in  consequence 
are  stronger  and  more  fully  developed  at  birth. 

The  "  Consultations  des  Nourrissons  "  were  founded  by  the 
late  Professor  Budin,  and  are  now  to  be  seen  in  France  in  con- 
siderable numbers.  The  scheme  included  advice,  and  in  some 
cases  assistance,  to  pregnant  women,  and  advice  and  assistance 
to  mothers  with  reference  to  the  feeding  of  the  infant.  The 
mother  is  always  encouraged  to  suckle  the  child  for  the  full 
period;  but  those  who  are  dependent  partially  or  entirely  upon 
artificial   feeding   are   provided   with   sterilized   milk,    and   the 


332  HYGIENE   AND   PUBLIC   HEALTH 

infant's  weight  is  weekly  registered.  These  mothers'  cHnics 
have  been  aptly  called  "  Ecoles  des  Meres."  A  somewhat  similar 
provision  first  founded  at  Fecamp  in  1894  was  termed  the  "  Gout 
de  Lait."  Dr.  J.  F.  J.  Sykes  and  others  have  drawn  attention 
to  the  increased  immaturity  of  infants  at  birth  during  recent 
years,  and  to  the  fact  that  this  diminished  viability  cannot  be 
due  to  artificial  feeding,  but  to  the  ante-natal  condition  of  the 
mother;  and,  as  Dr.  Sykes  pointed  out,  the  fundamental  idea  of 
the  Home  for  Mothers  provided  in  the  Borough  of  St.  Pancras, 
London,  is  that  the  pre-natal  conditions  of  the  mother  are  of 
primary  concern,  and  of  the  post-natal  conditions  the  mother 
should  receive  the  first  consideration ;  that  mothers  must,  wher- 
ever it  is  possible,  be  prevailed  upon  to  suckle  their  infants; 
and  that  in  order  to  make  the  provision  really  effective,  the 
co-operation  of  medicil  practitioners,  medical  attendants  at 
provident  dispensaries,  the  medical  staffs  of  hospitals,  midwives, 
nurses,  district  visitors,  and  the  philanthropic  public,  must  be 
secured. 

Meat. 

Meat  contains  a  large  quantity  of  nitrogenous  material,  some 
fat,  and  salts — chiefly  the  chlorides  and  phosphates  of  potash. 
It  is  rapidly  digested  and  easily  assimilated,  and  hastens  tissue 
metamorphosis. 

The  albuminoids  form  about  20  per  cent,  of  raw  meat  (beef), 
of  which  about  15-5  parts  are  digestible  albumins,  peptones,  and 
extractives,  the  remaining  4-5  parts  being  indigestible. 

Bones  contain  a  large  amount  of  nourishing  material,  viz., 
albuminoids  (gelatine),  24  per  cent.;  fat,  11  per  cent.;  ash  or 
mineral  salts,  48  per  cent.  A  most  nourishing  soup  can  be  pre- 
pared by  boiling  bones. 

In  inspecting  meat,  the  muscles  should  be  found  firm  and 
elastic,  of  a  deep  red  colour  (neither  purple  nor  pale,  flabby  nor 
sodden),  and  marbled  with  fat,  in  well-conditioned  animals. 
There  should  be  no  excess  of  moisture,  no  pus  or  fluids  in  the 
intermuscular  cellular  tissue,  and  no  lividity  on  cutting  the  muscle 
across.  The  flesh  must  be  quite  free  from  deposits  (tumours). 
The  odour  should  be  fresh  and  not  unpleasant,  without  a  suspicion 
of  putridity  or  smell  of  physic.  Meat  which  has  commenced  to 
putrefy  is  pale  and  soft;  the  reaction  of  the  juices  is  no  longer 
acid;  and  later  the  meat  becomes  greenish.  If  the  odour  of 
putrefaction  is  not  otherwise  appaient,  a  knife  or  a  new  wooden 


MEAT 


333 


skewer  should  be  thrust  into  the  meat  and  then  held  to  the 
nose;  or  a  little  of  the  meat  may  be  chopped  up  and  soaked 
in  hot  water,  when  the  steam  arising  may  be  found  offensive. 
The  fat  should  be  firm  and  of  a  pale  yellow  colour,  and  free  from 
haemorrhagic  points.  The  lymphatic  glands  afford  an  excellent 
clue  to  the  existence  of  disease  if  they  are  enlarged,  congested, 
or  show  deposits.  In  bovines  the  chief  lymphatic  glands  are 
to  be  looked  for  immediately  in  front  of  the  spinal  column 
(thoracic  and  lumbar  glands),  between  the  two  lungs  (medias- 
tinal), and  on  both  sides  of  the  trachea  or  wind-pipe  near  to  its 
bifurcation  (bronchial).  In  health  these  lymphatic  glands  are 
about  the  size  of  a  pea.  Any  lymphatic  glands  attached  should 
be  firm,  slightly  moist,  and  of  a  pale  greyish-yellow  colour  on 
section;  and  the  marrow  of  the  bones  should  be  light  red.  The 
lungs  should  be  examined  for  inflammation  or  abscesses,  tuber- 
culosis, or  actinomycosis;  the  Hver  for  distoma  or  liver-fluke, 
tuberculosis,  or  hydatid  tumours;  and  the  spleen  for  enlargement 
or  nodules. 

The  Important  Parasites  of  Flesh. 

Cysticerci. — 'The  cysticercus,  or  "  bladder- worm,"  causes  the 
condition  known  as  "  measles  "  in  the  pig,  ox,  and  sheep.     When 
measly  flesh  is  consumed  by  man, 
the  "  bladder-worm  "  undergoes  a 
series  of  changes  which  terminate 
in  its  conversion  into  a  tape- worm. 
In  the  flesh  of  the  pig,  and  much  Fig. 56.— "Measly" pork, show 
more     rarely    in    that    of    dogs,     '^g    (diagrammatically)    its 

APPEARANCE  TO  THE  NAKED  EYE. 

man,  a  number  of 

small  oval  or  round  cysts  are  seen,  occupying 
a  position  between  the  muscle-fibres,  and  com- 
monly varying  in  size  from  a  pea  to  a  cherry 
— though  they  have  been  found  as  small  as 
775  inch,  and  as  large  as  |  inch  in  diameter. 
These  cysts  are  the  Cysticerci  celluloses — the 
bladder-worms  which  form  a  stage  in  the 
development  of  Tcenia  solium.  The  cysticerci 
are  surrounded  by  a  pale  milky-looking  fluid, 
and  the  cyst  wall  shows  a  white  spot  (generally 
central)  upon  its  surface.  The  affected  flesh 
is  pale,  soft,  unduly  moist,  and  flabby,  and  it  has  a  smooth 
slippery  feel.      Sometimes  there  is  some  degree  of  calcification 


monkeys,  or 


Fig.  57. — Head  of 

t^nia  solium. 

(Obj.  ^  inch.) 


334 


HYGIENE  AND  PUBLIC  HEALTH 


of  the  capsule,  the  result  being  that,  when  sections  are  cut,  a 
grating  sensation  is  experienced. 

The  bladders  should  be  incised  with  a  sharp  knife,  and  the 
worm  examined  by  a  powerful  hand  lens,  when  at  one  ex- 
tremity will  be  found  the  blunt  square  head  provided  with  a 
sucker  at  each  "  angle,"  and  a  fringe  of  booklets  placed  more 
centrally.  These  booklets  are  very  characteristic,  and  must 
always  be  found  before  a  definite  diagnosis  is  ventured  on. 

Those  cysts  that  are  dried  up  and  indistinct  can  be  made 
visible  by  soaking  in  weak  acetic  acid.  Ostertag  attaches  great 
diagnostic  importance  to  the  rounded  or  oval  calcareous  cor- 
puscles, which  are  so  generally  embedded  in  the  tissue  of  the 
head,  but  which  disappear  on  the  addition  of  acetic  acid. 

Young  pigs  are  more  especially  liable  to  be  attacked;  and 


Fig.   58. — Head  of  T^nia 
mediocanellata. 

(Obj.  i  inch.) 


Fig.   59. 


—  Brood  capsule  of  an 
echinococcus. 


during  life  the  earliest  evidence  of  the  parasites  is  afforded  by 
the  presence  of  one  or  more  small  cysts  in  the  conjunctiva,  or 
in  the  loose  tissue  of  the  fraenum  linguae.  After  death  the  liver 
and  the  muscles  of  the  shoulders,  intercostals,  and  loins,  are  seen 
to  be  chiefly  affected. 

The  Cysticercus  of  the  Ox. — Cysticercus  bovis,  or  "  beef-measles," 
which  chiefly  affects  the  calf,  possesses  a  flat  head  armed  with  no 
booklets,  but  simply  with  suckers,  around  which  there  is  fre- 
quently a  considerable  deposit  of  pigment;  and  on  the  surface 
of  the  head  there  is  a  pit-like  depression  ("  frontal  suction  cup  "). 
It  develops  in  man  into  the  adult  tapeworm  called  Tcenia  medio- 
canellata,  which  is  longer  than  T.  solium,  and  appears  to  be  more 
prevalent  in  this  country. 

Bothrioccphalus  lahis,  a  tapeworm  which  is  almost  limited 
to  certain  parts  of  the  Continent  of  Europe,  is  even  larger  than 


MEAT  335 

T.  mediocanellata.  It  has  a  club-shaped  head,  not  armed  with 
hooklets,  but  possessing  two  deeply  grooved  longitudinal  suckers, 
one  on  each  side. 

Tcenia  echinococctis  is  the  small  tapeworm,  of  three  or  four 
segments,  with  a  head  provided  with  suckers  and  hooklets,  which 
is  commonly  found  in  the  dog.  The  encysted  form  ("  hydatids  ") 
is  generally  found  in  the  lungs  and  liver  of  oxen,  sheep,  and  swine, 
and  in  man  when,  as  more  particularly  in  Iceland,  he  lives  in  close 
association  with  dogs.  The  hydatids  consist  of  thin  pale  vesicles 
floating  in  a  clear  liquid,  the  whole  being  encysted  in  a  tough 
capsule.  The  inner  lining  of  the  capsule  consists  of  ciliated 
epithehum;  and  from  the  inside  of  the  cyst  wall  there  generally 
arise  many  so-called  "  brood  capsules  "  (fig.  59). 

The  condition  is  diagnosed  with  certainty  by  the  microscope 
either  by  the  discovery  of  the  characteristic 
heads  or  of  detached  hooklets  in  the  clear 
liquid  of  the  cyst.  Valuable  corroborative 
evidence  is  furnished  by  the  fact  that  the 
liquid  is  quite  free  from  albumin,  and,  in 
consequence,  does  not  coagulate  on  boiling. 

Trichina  Spiralis. — This  parasite  has 
been  found  in  the  flesh  of  many  different 
animals  (pigs,  pigeons,  eels,  etc.),  but  most 
commonly,  by  far,  in  that  of  pigs.  Oxen  and 
sheep  do  not  suffer  from  attack  by  these 
nematodes. 

The  shape  of  the  minute  worms  is  nearly 
that  of  a  typical  nematode,  i.e.,  a 
slender  rounded  body  tapering  gradually 
at  either  end.  The  extremity  which  constitutes  the  head, 
proceeds  to  a  long  slender  point  having  a  small  central  orifice — 
the  mouth;  the  other  extremity,  the  tail,  ends  more  bluntly. 
The  worms  possess  a  distinct  alimentary  canal,  and  even  rudi- 
mentary sexual  organs  are  present.  In  the  female  a  uterus  is 
discernible,  which  will  frequently  be  seen  to  be  full  of  minute 
free  embryos  curved  upon  themselves;  these  latter  have  been 
observed  to  become  extruded  from  the  vagina,  and  subsequently 
to  move  sluggishly  about  the  field  of  the  microscope.  The  male 
worm  is  much  smaller  than  the  female,  and  is  only  about  yV  inch 
long  when  mature ;  the  female  reaches  to  i-  inch.  The  long  slender 
head  and  blunt  tail  are  two  characteristics  which  serve  to  dis- 


FiG.  60. — Trichin.a. 

SPIRALIS  ENCYSTED 
IN    MUSCLE. 

( X  about    40    dia- 
meters.) 


336  HYGIENE    AND    PUBLIC    HEALTH 

tinguish  these  worms  from  parasites  which  otherwise  resemble 
them,  such  as  Dracunculus  and  Filaria  sanguinis  hominis. 

The  small  worms  are  mostly  coiled  up  in  cysts,  so  disposed 
that  their  longest  diameter  is  in  line  with  the  muscular  fibres; 
and  a  drop  of  acid  will  stimulate  them  to  transient  movements 
if  they  are  alive.     These  cysts  lie  between 
the  muscle   fibrillae,  and  their  walls   are 
sometimes  partially  or  completely  calcified, 
so  as  to  give  a  grating  sensation  when  the 
finger  is  passed  over  a  section  of  the  flesh. 
This  calcareous  deposit  serves  to  shield  the 
Fig.   6i.  — One    of     parasites  from  the  destructive  consequences 
Rainey's  capsules.       of  salting,  and  to  a  sHght  extent  also  from 
^^     ^''  heat  when  the  flesh  is  being  cooked.  There 

may  be  from  one  to  three  trichinae  in  a  cyst.  Frequently 
25  per  cent,  of  these  parasites  are  encysted  in  the  diaphragm  of 
the  host;  and  therefore,  when  possible,  a  piece  of  this  muscle 
should  be  procured.  The  back  muscles,  on  the  other  hand,  are 
the  least  attacked. 

Either  a  section  may  be  made  of  the  muscle,  or  it  may  be  teased 
out  with  needles;  and  preferably,  in  the  case  of  a  long  muscle,  a 
point  near  its  insertion  should  be  selected  for  teasing — since  this 
is  a  favourite  site  for  encystment.  The  affected  muscle  is  seen 
to  be  pale  and  oedematous;  and,  if  the  worms  are  encapsuled, 
small,  rounded  (or,  more  truly,  lemon-shaped),  whitish  specks, 
averaging  about  the  size  of  a  very  small  pin's  head,  are  visible 
to  the  naked  eye.  These  can  be  made  very  distinct  by  means  of 
a  hand  lens;  but  a  low  power  of  the  microscope  should  be  em- 
ployed in  every  case.  The  most  characteristic  appearance  will 
be  got  by  making  a  thin  longitudinal  section  of  the  affected  muscle, 
and  immersing  this  in  potassic  hydrate  solution  of  medium  strength 
— which  serves  to  make  the  muscle  fibres  transparent,  and  leaves  • 
the  worm  exposed  in  its  coiled  condition  within  the  capsule. 
The  soaking  should  not  be  prolonged  beyond  a  minute  or  two 
or  the  worm  itself  will  also  be  cleared  up.  Glycerine  is  a  good 
mounting  medium  when  a  permanent  specimen  is  desired. 
Sometimes,  owing  to  a  considerable  calcareous  deposit  in  and 
around  the  walls  of  the  capsule,  a  view  of  the  worm  is  obscured ; 
in  these  cases  a  drop  of  dilute  hydrochloric  acid,  run  under  the 
cover-glass,  will  dissolve  this  deposit ;  or  if,  as  is  sometimes  the 
case,  one  or  more  oil  globules  partially  obscure  the  worm,  a  drop 


MEAT  337 

of  ether,  applied  in  a  similar  manner  to  the  acid,  will  clear  away 
the  fat.  There  are  generally  oil  globules  at  the  poles  of  the 
capsule. 

The  parts  of  the  body  which  are  most  hkely  to  be  affected  will 
easily  be  remembered  if  it  be  borne  in  mind  that  the  worms 
migrate  to  their  settlements  from  the  gastro-intestinal  tract,  and 
chiefly  from  the  commencement  of  the  small  intestine.  The 
diaphragm,  the  liver,  the  intercostal  and  abdominal  muscles, 
are  necessarily  the  first  encountered,  and  therefore  suffer  most; 
but  in  later  stages  of  the  infection  there  is  hardly  a  muscle  which 
may  not  be  affected.  It  is  also  a  common  practice  to  make  an 
effort  to  diagnose  the  presence  of  the  parasites  in  the  living  animal, 
by  examining  the  eyes  and  the  under  surface  of  the  tongue,  both 
of  which  will  frequently  show  the  small  pinhead  deposits. 

The  dangerous  and  often  fatal  disorder  created  by  these  worms, 
as  they  traverse  the  gastro-intestinal  walls  and  travel  to  their 
encystment  in  the  various  organs  of  the  body,  is  most  prevalent 
in  those  countries  where  the  uncooked  or  imperfectly  cooked 
flesh  of  the  pig  is  consumed,  as  in  the  form  of  sausages, 
ham,  etc. 

Hot  smoking  and  efficient  cooking  destroy  these  parasites, 
but  in  the  latter  case  the  meat  must  be  "  done  through  " — i.e., 
thoroughly  cooked  through  the  centre — or  some  of  the  parasites, 
especially  when  shielded  by  calcareous  walls,  may  escape  the 
temperature  necessary  to  destroy  them — that  of  150°  F. 

There  are  certain  small  semi-transparent  bodies,  called  "  psoro- 
spermia,"  or  "  Rainey's  capsules,"  which  somewhat  closely  re- 
semble trichinae,  presenting  as  they  do  small  dark  oval  or  elHptical 
bodies,  of  greater  lengths,  however,  than  encysted  trichinae. 
They  are  made  up  of  a  thick  membrane,  formed  by  small  hairhke 
fibres  arranged  in  lines,,  which  encloses  small  oval  or  kidney- 
shaped  granular  cells,  closely  adherent  together;  and  the  whole 
Hes  embedded  in  the  muscle  substance  itself,  i.e.,  the  sarcolemma. 
They  are  extremely  common,  and  may  exist  in  the  flesh  of  most  of 
the  animals  used  for  human  consumption,  and  apparently  when 
eaten  they  do  no  harm. 

Several  more  obscure  bodies,  the  nature  and  significance  of 
which  we  are  still  more  ignorant  of,  may  exist  in  flesh,  such  as 
bodies  somewhat  resembling  pus  cells,  and  others  forming  minute 
concretions  or  tiny  hard  nodules.  Interesting  as  these  are 
pathologically,  they  are  rare,  and  when  present  even  in  consider- 


338  HYGIENE   AND    PUBLIC    HEALTH 

able  numbers  do  not  appear  to  affect  the  wliolesomeness  of  the 
meat  to  any  degree. 

Actinomycosis.' — The  "  ray-fungus  "  (actinomycosis),  one 
of  the  "fission  fungi,"  is  now  becoming  recognized  as  a  parasite 
of  commoner  occurrence  in  the  ox  than  was  once  suspected.  The 
difficulties  which  stood  in  the  way  of  an  earlier  appreciation  of 
this  fact  arose  from  the  circumstance  that  both  the  ante-  and 
post-mortem  appearances  of  the  disease  closely  simulate  those  of 
tuberculosis. 

It  has  not  yet  been  proved  that  the  disease  can  be  communi- 
cated by  the  cooked  flesh  of  animals  (bovines)  suffering  from  an 
attack,  for  the  vitahty  of  the  fungus  when  exposed  to  heat  is 
very  slight.  The  subject  is  of  such  interest  and  importance, 
however,  that  a  few  additional  facts  are  appended. 

The   parasites   almost   entirely   affect   the   tongue,   the  jaws 

(especially  the  lower  one),  and  the  lungs,  where  they  may  be 

detected,  by  the  naked  eye,  as  small  dirty  white  specks  commonly 

about  the  size  of  a  very  small  pea,  but  varying  from  the  tiniest 

speck  up  to  J  inch  in  diameter.     The  parasites 

assume,   when   encysted,    a   peculiar  symmetrical 

appearance,  due  to  the  fact  that  they  consist  of 

small  linear  elements,   thicker  at   one  extremity 

than   at   the   other,    and   so   arranged   that   their 

smaller  extremities  are  all  directed  towards  a  central 

point ;  the  stellate  or  rayed  appearance  thus  created 

Fig.  62. —      is  sometimes  remarkably  regular  and  uniform.    The 

HEp\T°cuji      tongue  when   affected  is   hard   and  swollen,   and 

(Natural  size.)   prcsents   the   flattened   nodules   chiefly   upon    its 

dorsal  aspect. 

DiSTOMA  Hepaticum. — To  examine  for  these  parasitic  trema- 

todes  the  liver  should  be  taken,  and  the  bile  ducts  carefully 

exposed.     The  parasites  will  be  found  as  small  organisms  of  a 

pale  brown  colour,  in  shape  like  little  soles,  and  provided  at  their 

broad  extremity  with  a  sucker  for  attachment  to  the  walls  of 

the  bile  ducts.     Their  surfaces  are  beset  with  many  little  warty 

points,  and  they  average  in  size  from  i  to  i|  inches  in  length, 

and  about  -|  inch  in  width.     They  generally  attach  themselves 

to  the  biliary  ducts,  but  they  may  be  found  also  in  the  parenchyma 

of  the  liver. 


MEAT  339 

The  Life-histories  of  the  Animal  Parasites  of  Man. 

Tcenia  solium. — Portions  of  the  ripe  proglottides  of  the  fully 
matured  tapeworm  are  swallowed  by  pigs,  or  more  rarely  by  dogs, 
monkeys,  or  man.  Very  commonly  the  ova  they  contain  escape 
and  become  scattered — some  into  water,  others  upon  grass  or 
vegetables,  where  they  may  certainly  survive  for  some  days.  It 
the  eggs  are  ingested,  on  reaching  the  stomach  the  shell  becomes 
dissolved  by  the  gastric  juice,  and  the  embryo  (a  globular  body 
armed  with  three  pairs  of  booklets)  bores  its  way  through  the 
stomach  or  intestinal  walls,  and  finally  comes  to  rest  in  some 
part  of  the  body.  It  then  grows  in  size,  loses  its  six  booklets, 
and  after  a  time  develops  a  head  provided  with  four  suckers, 
and  armed  with  a  circle  of  minute  booklets  ("  bladder- worm," 
or  Cysticercus  cellulosce).  The  head  grows  out  from  the  inside  of 
the  bladder,  to  the  wall  of  which  it  is  attached  by  a  constricted 
part  known  as  the  neck  or  pedicle.  The  parasite  may  remain  in 
this  condition  for  long  periods,  or  may  shrivel  up  and  die,  for 
it  is  incapable  of  further  development  until  it  is  ingested  by  a 
carnivorous  animal.  When  this  occurs,  on  reaching  the  ahmen- 
tary  canal,  it  projects  its  head  and  neck  (by  invagination),  the 
bladder  part  is  dissolved  by  the  gastric  juice,  and  very  shortly 
transverse  lines  appear  on  the  neck,  which  increase  in  size  and 
so  separate  from  each  other,  until  after  a  few  weeks  a  jointed 
adult  tapeworm  results,  with  proglottides  charged  with  ova 
ready  to  commence  a  fresh  cycle. 

The  life-histories  of  Tcenia  medio canellata  and  Bothriocephalus 
latus  are  similar  to  that  of  T.  solium;  but  the  bladder-worm  of 
the  Bothriocephalus  .latus  is  supposed  to  inhabit  some  species  of 
fish  (perch,  pike,  and  salmon  trout  ?),  or  possibly  a  freshwater 
mollusc. 

Distoma  hepaticum. — The  ova  develop,  in  water,  into  ciliated 
embryos,  and  these  undergo  in  small  water  snails  [Limnceus 
truncatulus)  a  further  development  into  larvae.  These  larvae 
ultimately  become  Httle  organisms  resembling  tadpoles 
{cercaria),  which  either  remain  encysted  in  water  snails,  or 
leave  them  and  become  attached  to  grass.  They  are  generally 
taken  up  by  a  grazing  sheep,  but  very  rarely  man  also  becomes 
a  host. 

Tcenia  echinococciis. — -Of  the  three  or  four  segments  of  this 
tapeworm  the  last  one  only  contains  sexual  organs.     The  ova 


340  HYGIENE   AND   PUBLIC   HEALTH 

are  discharged  with  the  faeces  (commonly  of  dogs),  and  they 
probably  infect  cattle,  swine,  and  man  through  the  medium  of 
water  or  raw  vegetables.  On  entering  the  stomach  the  gastric 
juice  dissolves  the  shells  of  the  ova,  and  liberates  the  embryos, 
which  possess  six  booklets  in  two  rows;  by  means  of  these  hook- 
lets  the  embryo  bores  its  way  through  the  walls  of  the  intestine 
and  develops,  chiefly  within  the  liver,  into  so-called  "  hydatid 
cysts  ";  i.e.,  the  booklets  are  lost,  and  the  formerly  solid  embryo 
swells  out  into  a  vesicle.  Generally  a  number  of  protrusions 
("  daughter  cysts  ")  grow  from  the  interior  of  the  vesicle,  which 
itself  forms  a  cyst  ("  mother  cyst  ").  To  the  mother  cyst  the 
daughter  cysts  are  attached  by  a  pedicle,  which  ultimately 
becomes  detached.  Each  "  daughter  cyst  "  may  develop  "  grand- 
daughter cysts,"  and  thus  the  original  echinococcus  may  become 
full  of  small  cysts  of  varying  sizes  ("  pill-box  hydatids  ").  Finally 
the  little  buds  develop  into  "  brood  capsules,"  i.e.,  thin  walled 
sacs  which  remain  attached  by  a  pedicle,  each  sac  developing  a 
number  of  heads,  with  four  suckers  and  a  row  of  booklets 
apiece. 

Thus  the  encysted  form  of  these  parasites  possesses  the  distin- 
guishing feature  of  being  able  to  give  rise  to  a  large  number  of 
scolices,  most  of  which  are  capable  of  developing  into  the  adult 
worm  when  they  enter  another  host. 

Rarely  the  hydatid  throws  out  protrusions  externally. 

Ascaris  lumhricoides  (the  round- worm). — The  ova  of  the  females 
are  discharged  with  the  faeces  of  the  host,  and  then  they  become 
capable  of  furnishing  embryos,  a  power  not  hitherto  possessed. 
The  embryos  probably  have  an  independent  existence  (possibly 
in  water  or  in  some  intermediate  host — such  as  worms  or  insects) 
before  again  entering  the  human  body,  and  completing  their 
development.  The  parasites  inhabit  the  small  intestine,  are  of 
a  brownish-yellow  colour,  and  are  most  commonly  met  with  in 
people  who  live  amid  dirty  surroundings. 

Oxyuris  vermicularis. — These  fine,  white,  thread-like  parasites 
occupy  the  large  intestine.  The  ova,  unlike  those  of  A .  lumhri- 
coides, contain  embryos  prior  to  their  discharge;  but  probably 
these  are  incapable  of  further  development  until  they  have  passed 
with  the  faeces,  when  they  may  reinfect  the  same  individual  or 
others  occupying  the  same  bed,  etc.,  or  may  pass  into  water,  or 
become  deposited  upon  vegetables  and  fruit,  and  thus  again 
become  ingested. 


MEAT  341 

The  life-histories  of  Tricocephalus  dispar  (whip-worm)  and 
Sclerostomum  duodenale  (common  in  Egypt  and  Brazil)  have  not 
yet  been  definitely  ascertained.  It  is  not  yet  certain  by  what 
vehicle  the  ova  of  the  females  (which  develop  in  man)  infect  their 
host,  or  whether  in  either  case  there  is  an  intermediary  stage  of 
development  of  the  parasite. 

Bilharzia  hcematohia. — The  male  is  a  white  flattened  worm, 
J  inch  in  length;  posteriorly  the  sides  of  the  parasite  curve  to- 
wards each  other,  and  meet  to  form  a  channel,  in  which  the  long 
slender  female  (f  inch  in  length)  lies  during  fecundation.  The 
ova  possess  a  beak,  which  generally  projects  from  one  end,  but 
sometimes  laterally.  These  ova  may  be  hatched  before  the 
parasite  leaves  the  tissues  of  the  orginal  host,  but  the  embryos 
are  not  born  until  afterwards.  If  the  ova  find  their  way  into 
water,  their  walls  swell  up  and  rupture,  and  the  minute  embryos 
escape,  armed  with  cilia,  which  serve  to  project  them  through 
the  water.  Probably  the  embryo  becomes  attached  to  some 
freshwater  mollusc  (or  possibly  some  fish),  and,  developing  into 
a  cercaria  form,  is  ingested  as  such  b}^  man,  and  then  completes 
its  cycle  of  development. 

Trichina  spirali'i. — When  trichinous  meat  is  consumed,  the 
trichina  embryos  (averaging  a  little  over  o-i  mm.  in  length), 
which  resemble  small  filariae,  bore  their  way  through  the  intes- 
tines and  reach  the  tissues.  They  always  become  encysted  in 
muscle  fibres,  where  they  increase  in  size  (up  to  o-6  to  i  mm.  in 
length),  and  acquire  an  ahmentary  canal  and  sexual  organs. 
The  encysted  worms  remain  quiescent  for  long  periods,  and  may 
ultimately  die;  but  if  trichinous  flesh  is  eaten  they  give  origin, 
through  their  embryos,  to  a  fresh  cycle  of  existence. 

Horseflesh. 
By  the  Horseflesh  Act  (1889)  powers  are  given  to  the  Officers 
of  the  Local  Sanitary  Authority,  for  the  inspection,  examina- 
tion, and  seizure  of  horseflesh  sold  for  human  food,  from  any 
shop  or  stall  not  conspicuously  labelled  "  Horseflesh  is  sold  here." 
It  becomes  necessary,  therefore,  in  order  to  check  fraud,  to  be 
familiar  with  the  chief  differences  which  exist  between  the  meat 
of  the  ox  and  that  of  the  horse.  In  horseflesh  the  meat  is  of  a 
darker  red,  and  sometimes  brownish  in  hue;  it  is  coarser — the 
muscular  fasciculi  being  broader — than  in^oxflesh;  the  odour  of 
the  fresh  meat  is  different,  and  after  the  lapse  of  a  day  or  two. 


342  HYGIENE    AND    PUBLIC    HEALTH 

as  the  flesh  dries,  it  develops  a  peculiar  faint  odour  and  imparts 
a  soapy  feeling  to  the  fingers.  The  fat  is  more  yellow  and  soft, 
and  possesses  a  sickly  taste,  and,  in  consequence,  it  is  sometimes 
removed  and  replaced  by  ox  fat,  which  is  skewered  on  the  meat. 
If  the  bones  have  not  been  removed,  they  will  afford  an  additional 
clue,  inasmuch  as  they  are  larger,  and  their  extremities  (tuber- 
osities, etc.,  for  the  attachment  of  muscles  and  ligaments)  are 
larger  and  more  marked,  these  signs  being  additional  to  some 
anatomical  differences  in  the  construction  of  the  horse's  skeleton. 
For  instance,  the  horse  has  eighteen  ribs,  fixed  by  long  unions 
with  the  cartilages,  and  a  keel-shaped  sternum;  whereas  the  ox 
has  thirteen  ribs,  jointed  to  the  cartilages,  and  a  flat  and  broad 
sternum.  For  these  reasons  horseflesh  is  usually  boned  before  it 
is  offered  for  sale  as  beef. 

The  tongue,  kidney,  and  the  liver  of  the  horse,  together  with 
some  other  organs,  are  also  occasionally  placed  on  sale  as  the 
corresponding  organs  in  the  ox.  The  tongue  of  the  horse  is, 
however,  broad  and  round  at  its  free  end,  instead  of  pointed, 
as  in  the  ox;  and  if  the  hyoid  bone  is  attached,  it  is  found  to  be 
made  up  of  five  parts,  whereas  that  of  the  ox  consists  of  nine. 
Moreover  the  base  of  the  horse's  tongue  is  smooth  on  its  dorsal 
aspect,  whereas  that  of  the  ox  is  rough  from  very  prominent 
papillae.  The  epiglottis  is  smaller  and  more  pointed  in  the 
horse.  The  liver,  whether  of  the  ox  or  sheep,  consists  of  one 
very  large  lobe  and  another  relatively  small  one;  in  the  horse 
there  are  three  large  and  distinct  lobes,  and  a  fourth  relatively 
smaller  one,  and  there  is  no  gall  bladder.  The  kidney  of  the 
horse  is  more  heart-shaped  and  cannot  be  mistaken  for  the  long 
lobulated  kidney  of  the  ox. 

The  heart  of  the  horse  differs  from  that  of  the  ox  in  being  less 
conical,  darker,  softer,  and  with  less  fat  at  its  base;  and  without 
the  bone  that  is  found  in  the  heart  of  the  ox. 

Cooking. 

The  cooking  of  meat  preserves  it  from  putrefactive  changes  by 
heat  sterilization,  increases  its  digestibility,  and  produces  that 
palatability  which  a  civilized  taste  demands. 

By  cooking,  the  connective  tissue  binding  together  the 
muscular  fasciculi  tends  to  become  disintegrated.  The  con- 
nective tissue  is  changed  into  more  or  less  soluble  gelatin,  the 
meat  is  made  tender  and  easier  to  chew,  and  the  protcids  and 


MEAT  343 

fats  arc  more  perfectly  exposed  to  the  solvent  action  of  the 
digestive  juices.  The  flavour  induced  by  cooking  stimulates 
the  secretion  of  digestive  juices. 

In  all  cooking  processes  meat  loses  weight,  usually  from  20 
to  30  per  cent.  In  boiling  a  joint,  the  meat  should  be  plunged 
into  boiling  water  for  five  minutes  to  coagulate  the  outside 
albumin  and  retain  the  salts,  extractives  and  soluble  substances 
in  the  interior.  The  remainder  of  the  boiling  should  be  con- 
ducted at  a  temperature  below  170°  F. — which  is  the  temperature 
at  which  most  of  the  albuminoids  coagulate — ^in  order  that  the 
meat  may  not  become  tough,  dry,  and  indigestible.  On  the 
other  hand,  in  making  broth  the  meat  should  be  cut  into  small 
pieces,  and  placed  in  cold  water,  which  is  gradually  warmed  to 
150°  F. ;  in  this  way  the  salts  and  extractive  matters  pass  out 
of  the  meat  into  the  broth,  together  with  a  certain  proportion 
of  the  more  soluble  albuminoids. 

In  baking  and  roasting,  the  joint  of  meat  should  first  be  sub- 
jected to  an  intense  heat,  in  order  to  coagulate  the  outside 
albumin  and  retain  the  soluble  juices.  After  a  few  minutes  the 
temperature  should  be  lowered  'and  the  roasting  or  baking  com- 
pleted at  180°  F.  to  200°  F.  Aromatic  products  are  formed  in 
roasting  and  baking  which  are  volatilized ;  some  of  the  fat  is 
melted  and  flows  out  of  the  joint  together  with  gelatin  and 
extractives  to  form  the  gravy. 

The  gas  cooking  ovens,  which  have  now  come  so  largely  into 
use,  present  several  advantages  over  kitchen  ranges  heated  by 
coal.  They  are  very  cleanly;  the  temperature  of  the  oven  can 
be  adjusted  with  great  nicety  by  regulating  the  consumption  of 
gas;  there  is  the  convenience  of  the  oven  being  ready  for  use  in 
a  few  minutes  after  the  gas  is  lighted;  and  as  soon  as  the  cooking 
is  finished  the  gas  can  be  turned  out.  It  is  very  difficult  to 
distinguish  between  a  joint  of  meat  baked  in  a  gas  oven  and 
one  roasted  before  an  open  fire,  if  the  gas  oven  is  properly 
ventilated  and  a  flue  is  provided  to  carry  off  the  products  of 
combustion.  If  the  ventilation  is  insufficient  either  in  a  gas  oven 
or  ordinary  close  range  oven,  the  meat  becomes  sodden  in  its  own 
vapours,  and  in  the  case  of  the  gas  oven  also  with  the  gas  products, 
which  give  it  a  disagreeable  taste  and  odour.  Gas  cooking 
stoves  should  be  provided  with  Bunsen  burners,  arranged  round 
the  side  of  the  oven  at  the  bottom ;  and  the  oven  walls  should  be 
double,  the  space  between  the  plates  being  well  packed  with  slag 


344  HYGIENE   AND   PUBLIC   HEALTH 

wool  to  prevent  loss  of  heat.  No  soot  is  formed  in  gas  cooking, 
and  there  are  no  dust,  ashes,  and  dirt,  as  in  a  coal  cooking  range. 

Meat  can  be  preserved  by  drying  in  strips  in  the  sun,  called 
jerking;  by  salting;  by  canning,  i.e.,  by  heating  and  thereby 
sterilizing  the  meat  in  tins,  which  are  hermetically  sealed  by 
solder  at  a  high  temperature;  and  by  refrigeration  in  the  raw 
state — a  process  now  very  largely  used,  the  refrigeration  chambers 
on  board  ship  permitting  of  the  importation  into  this  country 
of  meat  from  South  America  and  the  Australian  colonies.  The 
last  process  is  by  far  the  best,  as  the  freshness  and  nutritive 
value  of  the  meat  remain  unaltered.  It  is  not  easy  to  distinguish 
a  New  Zealand  joint  of  mutton  from  the  home  product — if  it  is 
properly  thawed  before  being  cooked.  The  low  temperature 
of  the  ice  house  (not  less  than  6°  F.  below  freezing  point)  does  not 
destroy  all  bacteria,  but  prevents  the  development  of  the  organ- 
isms of  putrefaction.  The  preservation,  for  many  ages,  of  the 
Siberian  mammoth  in  its  icy  casing  is  a  notable  example  of  the 
antiseptic  properties  of  great  cold. 

Frozen  meat  can  generally  be  distinguished  bj^  the  uniform 
and  darker  colour  of  the  meat,  even  the  fat  being  stained  by 
the  exuded  juices  from  the  lean  parts.  It  is  also  softer  to  the 
touch.  The  external  surface  of  the  meat  is  duller  and  browner 
than  that  of  fresh  meat,  and  the  joints  are  not  usually  so  well 
dressed  as  in  the  case  of  home  killed  meat.  American  killed 
carcases  can  generally  be  told  by  the  bruises  about  the  legs,  by 
which  the  animals  are  hoisted  prior  to  slaughter. 

Effects  of  Diseased  or  Unsound  Meat. 

It  was  formerly  believed  that  thoroughly  cooked  meat  is  not 
likely  to  produce  any  injurious  effects,  even  when  derived  from  a 
diseased  animal,  or  after  putrefactive  changes  have  commenced 
in  it;  but  recent  research  tends  to  show  that  meat  which  is 
derived  from  a  diseased  animal,  or  which  has  become  tainted  by 
the  presence  of  putrefactive  bacteria,  may  possibly  be  cooked 
sufficiently  to  destroy  the  microbes  themselves,  whilst  the 
poisonous  products  of  the  microbes  are  unaffected  by  cooking. 
Tainted  meat,  eaten  hot,  is  sometimes  harmless,  but  wlien 
taken  cold  may  produce  symptoms  of  poisoning,  the  bacterial 
ferments  having  had  time  to  act  upon  the  albuminous  sub- 
stances of  the  meat.  Where  the  meat  is  only  partially  cooked, 
and  ynderdone  in  the  centre,  danger  is  still  more  likely  to  arise; 


MEAT  345 

and  in  such  cases  symptoms  of  poisoning,  occasionally  ending 
fatally,  have  been  observed  in  those  who  have  partaken  of 
decomposir.g  food.  A  large  number  of  instances  of  meat  poison- 
ing have  besn  connected  with  the  consumption  of  sausages,  pies, 
and  hams  (Welbeck,  Nottingham,  etc.).  The  symptoms,  which 
in  most  cases  supervene  in  from  six  to  eight  hours,  are  those  of 
violent  irritation  of  the  alimentary  tract,  and  are  characterized 
by  acute  vomiting,  diarrhoea  and  coHc,  increased  mucous  secre- 
tions, cramps  in  the  extremities,  and  failure  of  the  heart's  action. 
The  symptoms  are  produced  either  by  putrefactive  bacteria  or 
special  bacilli  In  the  food,  or  the  products  of  their  action  upon 
albuminous  sibstances — the  poisonous  alkaloids,  ptomaines,  or 
albumoses.  Where  the  poisoning  is  due  to  putrefactive  products 
it  is  termed  "  ptomaine  poisoning."  The  organisms  most 
generally  concerned  are  Bacillus  proteus  and  B.  coli.  These  are 
killed  in  ordinary  cooking,  and  the  toxin  of  B.  proteus  is  also 
destroyed. 

Where  the  illness  commences  within  twelve  hours  after  par- 
taking of  the  food,  the  probability  is  that  the  poisonous  condition 
of  the  food  was  due  to  already  formed  toxins ;  but  where  a  period 
of  twelve  to  forty-eight  hours  or  longer  supervenes  between  the 
consumption  of  the  food  and  the  illness,  the  action  of  bacteria 
is  indicated,  requiring,  as  they  do,  time  for  their  growth  and 
development,  and  for  the  production  within  the  body  of  the 
toxins,  the  absorption  of  which  gives  rise  to  the  symptoms  of 
poisoning.  In  some  instances  the  symptoms  of  ptomaine  (food) 
poisoning  have  borne  a  strong  resemblance  to  those  indicative  of 
poisoning  by  the  alkaloid  muscarine. 

Besides  a  muscarine-like  poison,  there  appears  to  be  another 
poison  formed  in  decomposing  flesh,  which  produces  symptoms 
analogous  to  those  of  atropine,  viz.,  quickened  pulse,  paralysis 
of  the  muscles  of  the  eyeball,  difficulty  of  swallowing,  dryness  of 
the  mouth  and  throat,  constipation,  and  diminished  secretion 
from  the  mucous  membranes.  This  poison  exerts  an  antagon- 
istic effect  upon  the  muscarine-like  poison ;  and  in  different  cases 
one  of  these  poisons  may  predominate  over  the  other,  and  produce 
its;  characteristic  symptoms  more  or  less  modified.  The  group 
of  symptoms  similar  to  those  occurring  in  atropine  poisoning  give 
rise  to  the  condition  known[fas  "  botulism,"  from  the  circum- 
stance that  they  have  been  most  frequently  observed  as  the 
result  of  eating  bad  sausages  {botulus — a  sausage) .     The  toxin  of 


346  HYGIENE    AND    PUBLIC    HEALTH 

"  botulism  "  is  produced  by  the  anaerobic  Bacillus  holulinus,  and 
symptoms  generally  appear  in  from  twenty-four  jo  thirty-six 
hours.  This  condition  is  to  be  distinguished  from  allied  condi- 
tions which  are  characterized  almost  exclusivel/  by  gastro- 
intestinal symptoms,  and  are  due  to  the  Bacillus  enteritidis  of 
Gaertner,  or  the  paratyphoid  organisms,  the  agents  most  com- 
monly found  to  be  causative  of  meat-poisoning.  The  animal 
prior  to  death  had  probably  suffered  from  disease  of  the  gastro- 
intestinal tract,  or  some  form  of  septic  infection,  and  the  out- 
breaks are  most  frequent  in  summer.  The  toxin  is  very  resistant 
to  heat;  and  the  mortality  of  outbreaks  varies  from  2  to  5  per 
cent,  of  those  attacked.  The  diagnosis  of  this  form  of  poisoning 
is  based  upon  the  isolation  of  the  bacilli  from  the  stools,  or  (after 
death)  the  organs  of  the  body,  the  feeding  of  mice,  etc.,  upon 
the  cultures,  and  the  agglutination  test  with  the  patient's  serum 
upon  known  cultures  of  the  various  organisms. 

The  presence  of  alkaloidal  substances  may  possibly  account 
for  the  ill  effects  produced  by  eating  oysters,  mussels,  and  some 
kinds  of  fish,  such  as  mackerel,  when  out  of  season,  and  pork 
in  hot  climates. 

It  is  maintained  by  some  that  scurvy  is  a  form  of  toxic  poison- 
ing from  food. 

There  is  also  some  evidence  that  acute  diarrhoeal  attacks  may 
be  due  to  the  ingestion  of  sound,  wholesome  food,  which  has  been 
accidentally  inoculated  with  the  Bacillus  enteritidis  of  Gaertner 
after  cooking.     An  investigation  by  one  of  the  authors  into 
an  outbreak  of  acute  febrile  diarrhoea  attacking  a  very  consider- 
able proportion  of  those  who  had  partaken  of  a  certain  meal, 
showed  that   the  cook   had  suffered  from  an   acute   diarrhoea 
whilst  engaged  in  preparing  the  food  on  the  day  previous  to  the 
meal.     The  food  so  prepared  was  stored  during  the  night  (warm 
weather  prevailing  at  the  time),   and  was  eaten  cold  on  the 
following  day.     All  the  food  was  sound  when  received  for  cooking, 
and  no  particu  lar  article  of  food  was  especially  indicated  as  the 
source  of  the  mischief.    In  a  great  majority  of  the  attacks  of 
diarrhoea  there  was  an  incubation  period  of  thirty-six  to  forty- 
eight  hours.    The  evidence  pointed  strongly  to  contamination  of 
the  prepared  food  by  the  dirty  hands  of  the  cook  whilst  suffering 
from  an  acute  diarrhoea,  the  probability  being  that  Gaertner's 
bacillus  was  directly  inoculated  into  the  food  by  this  means. 
In  investigating  a  case  of  food  poisoning,  it  is  best  to  enter  on  a 


MEAT  347 

paper  every  article  that  has  been  consumed  in  the  affected 
household  or  households,  and  then  by  a  process  of  exclusion  to 
determine  the  article  or  articles  that  have  been  eaten  in  common 
by  the  sufferers.  The  suspected  article  must  then  be  traced 
.(ind  secured,  and  the  correctness  of  the  conclusion  confirmed 
L»y  feeding  experiments  on  one  of  the  lower  animals  and  a 
bacteriological  investigation. 

T.\iere  are  certain  diseases  of  animals  which  are  known  to  be,  or 
believed,  on  good  grounds,  to  be  transmissible  to  man.  These 
are  anthr^ax  and  malignant  pustule,  tubercle,  foot  and  mouth 
disease,  rabiss,  glanders  and  farcy  in  horses,  Cysticercus  celluloscB 
and  bovis  in  the^pig  and  ox,  respectively,  and  Trichina  spiralis  in 
the  pig.  With  tiie  exception  of  cysticercus  and  trichina  these 
diseases  are  far  more  frequently  transmitted  to  man  by  other 
means  than  by  the  consumption  of  diseased  flesh.  But  it  must 
be  remembered^ that  such  transmission  is  possible  in  respect  of 
several  diseases,  and  would  probably  be  much  more  frequent 
than  it  is,  were  it  not  for  the  precautions  taken  to  prevent  the 
sale  of  unsound  meat,  and  for  the  safeguard  of  cooking. 
In  some  diseases  it  is  generally  held  to  be  sufficient  to 
condemn  the  affected  parts,  if  the  rest  of  the  carcase  appears 
healthy. 

The  Report  of  the  Royal  Commission  (1895)  appointed  to 
inquire  into  the  effect  of  food  derived  from  tuberculous  animals 
on  human  health,  is  worthy  of  careful  study.  As  regards  the 
prevalence  of  tuberculosis  in  food  animals  the  records  of  the 
Copenhagen  and  Berlin  slaughter  houses  show  that  from  15  to 
18  per  cent,  of  the  oxen  and  cows  slaughtered  are  tuberculous, 
of  calves  only  from  o-i  to  0-2  per  cent,  are  tuberculous,  of 
sheep  only  0-0003  to  0-0004  P^r  cent.,  and  of  swine  1-55  to 
15-3  per  cent.,  the  latter  figure  applying  to  the  Copenhagen  and 
the  former  to  the  Berlin  swine.  For  milch  cows  there  are  no 
figures  available  on  a  large  scale;  but  of  300  milch  cows  which 
were  slaughtered  in  Edinburgh  in  1890,  on  account  of  the  appear- 
ance of  epidemic  pleuro-pneumonia  there,  120,  or  40  per  cent., 
were  found  to  be  tuberculous  on  post-mortem  examination. 
There  is  no  doubt  that  milch  cows  suffer  far  more  frequently 
than  oxen,  heifers,  or  bulls,  and  that  tuberculosis  is  more  fre- 
quently found  in  the  carcases  of  cows  than  in  any  other  animal 
slaughtered  for  sale.  From  the  experiments  made  for  the 
Commission    by   Sidney   Martin,    it    appears   that    tuberculous 


348 


HYGIENE    AND    PUBLIC    HEALTH 


deposits  are  but  seldom  found  in  the  meat  substance — the 
muscular  tissue — of  the  carcase  of  an  affected  animal.  They  are 
principally  found  in  the  organs,  membranes,  and  glands.  In 
cases  of  mild,  moderate,  and  localized  tuberculosis,  if  the  affected 
organs  are  discarded,  and  if  great  care  is  exercised  to  prevent 
smearing  and  contamination  of  the  meat  by  caseous  or  other 
tuberculous  material  adhering  to  the  butcher's  hands,  knives, 
and  cloths,  there  is  no  reason  why  the  rest  of  the  meat  should 
not  be  used  for  human  consumption.  As  at  present  practised, 
however,  in  this  country,  the  slaughtering  of  a  tuberculous 
animal  almost  necessarily  involves  the  contamination  of  the 
surfaces  of  the  joints  of  meat  with  infective  tubercular  material. 
In  cases  of  generalized  tuberculosis,  not  only  is  the  risk  of  con- 
tamination of  the  meat  in  dressing  the  carcase  greatest,  but 
there  is  also  no  certainty  that  tubercular  material  may  not 
be  present  in  the  muscular  substance,  or  in  glands  in  the  con- 
nective tissue  between  the  muscles,  and  consequently  the  carcases 
of  animals  so  affected  should  be  condemned  and  destro3'ed. 

The  necessity  for  skilled  and  well  trained  meat  inspectors  is 
dwelt  upon  by  the  Commissioners,  who  were  of  opinion  that  the 
following  principles  should  be  observed  in  the  inspection  and 
condemnation  of  tuberculous  carcases'of  cattle: — ■ 


(a)  When  there  is  miliary  tuberculosis  of  " 

both  lungs         ..... 

(b)  WQien  tuberculous  lesions  are  present 

on  the  pleura  and  peritoneum 

(c)  When  tuberculous  lesions  are  present 

in  the  muscular   system  or  in  the 

lymphatic  glands  embedded  in  or 

between  the  muscles 
{d)  When  tuberculous  lesions  exist  in  any 

part  of  an  emaciated  carcase  . 
(a)  When  the  lesions  are  confined  to  the 

lungs    and  the  thoracic  lymphatic 

glands      ...... 

{b)  When  the  lesions  are  confined  to  the 

liver         ...... 

(f)  When  the  lesions  are  confined  to  the 

pharyngeal  lymphatic  glands 

(d)  When  the  lesions  are  confined  to  any 

combination  of  the  foregoing,  but 
are  collectively  small  in  extent 


The  entire  carcase  and 
all  the  organs  may  be 
seized. 


The  carcase,  if  otherwise 
healthy,  shall  not  be 
condemned ;  but  every 
part  of  it  containing 
tuberculous  lesions 
shall  be  seized. 


"  In  view  of  the  greater  tendency  to  generalization  of  tuberculosis  in  the 
pig,  we  consider  that  the  presence  of  tubercular  deposit  in  any  degree 
should  involve  seizure  of  the  whole  carcase  and  of  the  organs. 

"  In  respect  of  foreign  dead  meat,  seizure  shall  ensue  in  every  case  where 
the  pleura;  have  been  '  stripped.'  " 


MEAT  349 

As  regards  cow's  milk,  tlic  Commissioners  found  that  there 
was  no  evidence  of  danger  to  the  consumer  even  when  the  milk 
is  derived  from  a  tuberculous  animal,  so  long  as  there  is  no 
disease  of  the  udder.  But  the  affection  of  the  udder  may  be 
jlresent  in  a  cow  not  otherwise  markedly  affected  with  tuber- 
culosis; and  the  infection  once  implanted  in  the  udder  may 
spread  with  alarming  rapidity.  The  milk  of  cows  with  tuber- 
culosis of  the  udder  possesses  a  high  degree  of  virulence;  and 
appear^  to  be  virulent  even  when  no  tubercle  bacilli  can  be 
demonstrated  in  it. 

More  recent  research  indicates  that  the  milk  of  tubercular 
cows  which  have  no  apparent  udder  disease  may  be  infective. 
Tubercle  bacilli  may  also  be  discharged  in  large  numbers  in  the 
alvine  excreta  of  tubercular  cows;  and  as  it  is  diflicult  to  exclude 
all  contamination  of  milk  by  such  excreta,  there  is  always  a  possi- 
bility of  the  milk  of  tubercular  cows  becoming  infective  in  this 
way,  even  apart  from  any  elimination  of  tubercle  bacilli  by  the 
mammary  glands. 

The  Commissioners  held  that  all  udder  diseases  should  be 
notified,  and  that  any  one  selling  milk  from  a  cow  with  diseased 
mammary  glands  should  be  liable  to  a  heavy  penalty;  they 
advocate  systematic  inspection  of  cows  by  veterinarians  as  a 
means  to  this  end.  This  recommendation  was  given  effect  to 
by  the  Dairies,  Cowsheds,  and  Milkshops  Order  of  1899,  by 
which  Article  15  of  the  Order  of  1885  is  amended,  so  that  the 
expressions  in  the  article  which  refer  to  "  disease  "  shall  include, 
in  the  case  of  a  cow,  such  disease  of  the  udder  as  shall  be  certi- 
fied by  a  veterinary  surgeon  to  be  tubercular.  Such  tubercular 
disease  ought  to  be  suspected  when  a  painless  hard  lump,  slowly 
enlarging,  can  be  detected  in  one  or  more  of  the  quarters  of  the 
udder. 

Further  recommendations  of  the  Commissioners  were  to  the 
effect  that  stock  owners  should  be  encouraged  to  test  animals 
by  the  gratuitous  supply  of  tuberculin,  and  the  offer  of  the 
services,  free  of  charge,  of  a  veterinary  surgeon;  that  better 
sanitary  conditions  should  be  enforced  in  cowsheds;  that  the 
closing  of  private  slaughter  houses,  and  the  enforced  use  of  public 
slaughter  houses  should  be  brought  about,  to  ensure  a  uniform 
and  equitable  system  of  meat  inspection;  and  that  foreign 
meat  should  be  required  to  bear  a  mark  of  inspection  and 
approval  stamped  upon  it  at  the  time  of  killing.     They  do 


350  HYGIENE   AND   PUBLIC   HEALTH 

not  recommend  compensation  to  the  owners  of  condemned 
carcases. 

The  influence  of  cooking  upon  tuberculous  meat  and  milk 
was  investigated  by  Sims  Woodhead,  who  arrived  at  the  follow- 
ing conclusions:  "  In  the  boiling  and  roasting  experiments,  as 
ordinarily  carried  out  in  the  kitchen,  the  temperature,  however 
high  it  may  be  near  the  surface,  seldom  reaches  140°  F.  in  the 
centre  of  a  joint,  except  in  the  case  of  joints  under  6  pounds  in 
weight.  Ordinary  cooking  is  quite  sufficient  to  destroy  any 
smeared  (infective)  material  that  remains  on  the  outer  surface 
of  the  meat,  but  it  cannot  be  relied  upon  in  the  slightest  degree 
to  render  innocuous  the  same  smeared  material  when  in  the  centre 
of  a  roll."  Rolled  meat,  the  central  parts  of  which  had  become 
smeared  by  tubercular  matter,  were  not  sterilized  by  any  process 
of  cooking,  unless  the  roll  was  less  than  4  pounds  in  weight.  The 
least  reliable  method  of  cooking,  qud  sterilization,  is  roasting 
before  the  fire,  next  comes  roasting  in  an  oven,  and  then 
boiling. 

Probably  tuberculosis  is  not  conveyed  through  the  consump- 
tion of  the  flesh  of  tuberculous  animals  to  any  great  extent. 
This  view  is  supported  by  the  fact  that  the  reduction  in  the 
mortality  from  tuberculosis  has  been  very  marked  during  the 
age-periods  in  which  meat  is  most  largely  consumed;  and  the 
great  reduction  in  mortality,  between  185 1  and  1910,  has  been 
coincident  in  point  of  time  with  a  large  increase  in  the  amount 
of  meat  consumed  in  this  country. 

As  regards  the  sterilization  of  tuberculous  milk,  it  would 
appear  that  absolute  safety  is  only  to  be  attained  by  raising  the 
milk  actually  to  the  boiling  point.  The  Commissioners  were  of 
opinion  that  the  innocence  of  tubercular  milk  treated  in  this 
manner  was  not  entirely  demonstrated  to  their  satisfaction. 
When  the  tuberculous  material  in  milk  is  raised  to  temperatures 
insufficient  for  the  actual  destruction  of  the  virus,  it  is  possible 
to  obtain  from  the  most  deadly  tuberculous  material  a  weaker 
sort  of  tuberculous  matter,  so  tardy  in  its  operation  upon  test 
animals  as  to  simulate  the  slower  forms  of  consumption  seen  in 
the  human  subject,  or  when  used  to  feed  pigs — animals  having 
some  specialities  of  throat  (tonsillar)  structure  like  that  of  man 
— giving  rise  to  chronic  enlargements  of  the  cervical  ghuids, 
resembling  the  scrofulous  glands  so  common  in  children.  These 
observations,   the  Commissioners  think,   are  suggestive  of  the 


MEAT  351 

[)ssibility  of  widely  pn'valcnt  funns  of  human  tuberculosis 
^^aving  an  origin  in  milk. 

^^  Bovine  and  porcine  cysticerci,  which  develop  Tcenia  medio- 
^y-.ncllata  and  Tcenia  solium  respectively  in  man,  arc  probably 
P-^tle  affected  by  salting  and  smoking.  There  is,  however,  good 
ground  for  believing  that  exposure  for  some  minutes  to  a  tempera- 
ture above  150°  F.  destroys  them.  The  same  may  be  said  for 
the  Trichina  spiralis;  only  the  temperature  must  be  somewhat 
higher,  as  the  worm  is  surrounded  by  a  dense  capsule  which 
retards  the  passage  of  heat. 

The  most  common  condition  which  renders  flesh  unfit  for 
human  consumption  is  putrefaction.  The  whole  carcase  should 
be  condemned  in  marked  emaciation  from  disease  (but  not 
mere  leanness),  in  glanders,  anthrax,  generalized  tuberculosis, 
measles  and  trichinosis.  Localized  inflammatory  conditions  or 
suppuration,  early  actinomycosis,  localized  tuberculosis,  liver- 
fluke  and  echinococci,  do  not  justify  the  condemnation  of  the 
whole  carcase,  if  the  rest  of  the  flesh  is  firm  and  of  a  good  colour. 

The  meat  of  animals  which  have  been  slaughtered  in  the  early 
stages  of  acute  inflammatory  disease,  foot  and  mouth  disease,  and 
epidemic  pleuro-pneumonia  is  probably  quite  wholesome  if  well 
cooked,  unless  the  animals  have  been  drugged  with  medicines 
before  killing.  The  evidence  as  regards  the  possible  bad  effects 
from  the  use  of  meat  taken  from  animals  which  have  suffered 
from  rinderpest  or  cattle  plague,  swine  fever,  braxy  or  splenic 
apoplexy  (sheep),  and  smallpox  (sheep),  is  conflicting. 

A  certain  amount  of  the  meat  condemned  in  public  slaughter 
houses  may  be  used  for  human  food  under  the  following  circum- 
stances: (i)  It  may  be  dealt  with  in  public  kitchens  under  pre- 
cautions which  will  ensure  a  thorough  cooking,  and  the  cooked 
meat  or  soup  made  therefrom  may  be  sold  at  a  small  charge — 
as  in  the  Freibanks  in  Germany,  or  (2)  the  meat  can  be  sterilized 
by  steam  under  pressure,  and  then  sold.  If,  however,  it  is  unfit 
for  human  food  under  any  circumstances,  it  should  be  either 
made  into  manure  under  supervision,  or,  failing  this  supervision, 
it  should  be  saturated  with  petroleum,  carbolic  acid,  or  mineral 
acids,  before  it  is  allowed  to  be  removed,  in  order  to  ensure  that 
it  will  not  be  sold  as  food. 

The  arguments  in  favour  of  public  abattoirs  may  be  sum- 
marized as  follows:  They  constitute  the  only  possible  means  of 
proper  and  systematic  inspection  at   the  time  of  slaughter,  such 


352  HYGIENE   AND   PUBLIC   HEALTH 

inspection  being  necessary  to  prevent  the  sale  for  human  p<^d 
of  diseased  meat.  The  consumer  would  have  a  guarantee  h; 
home  killed  meat  was  good  and  wholesome,  and  this  would  p  k 
ably  increase  the  demand  for  it.  The  better  provisions  for  slauj.  ca- 
tering and  cooling  the  meat,  and  the  diminished  handling,  wou'ii  ' 
favour  its  good  appearance  when  exposed  for  sale.  If  public 
slaughter  houses  are  constructed  near  railway  stations,  the 
driving  of  cattle  through  crowded  streets  is  avoided.  On  the 
other  hand,  butchers  as  a  body  do  not  favour  these  establish- 
ments; and  slaughtering  is  likely  to  be  done  elsewhere,  unless 
private  slaughter  houses  are  at  the  same  time  abolished,  and  only 
stamped  meat  allowed  to  be  sold.  Butchers  argue  that  the  hand- 
ling and  carting,  entailed  by  the  removal  of  the  meat  from,  the 
abattoir,  tend  to  destroy  the  characters  of  home  killed  meat,  but 
this  argument  does  not  apply  if  suitable  carts  are  used  in  which 
the  meat  is  suspended  by  hooks  from  the  roof. 

The  buildings  of  a  public  abattoir  should  include  lairs  for 
animals  about  to  be  slaughtered,  separate  places  for  such  as  are 
unsound,  separate  slaughter  houses  for  the  different  kinds  of 
animals,  cold  storage  for  meat,  buildings  for  the  treatment  and 
disposal  of  the  offal  and  diseased  parts,  stables  and  sheds  for 
horses  and  vehicles  and  the  drivers'  dogs,  and  a  market  room  with 
restaurant.  There  must  be  an  ample  water  supply,  and  the 
means  of  making  ice  should  be  provided. 

Fish. 

Though  many  parasites  attack  fish,  the  encysted  form  of  the 
tapeworm  called  Bothriocephalus  latus,  which  is  sometimes  found 
in  the  pike  or  turbot,  is  the  only  one  which  is  known  to  be 
harmful. 

Oysters  and  mussels  have  been  known  to  produce  poisonous 
symptoms,  and  nettlerash  is  an  occasional  consequence  of  the  con- 
sumption of  the  latter.  The  common  symptoms  of  poisoning  are 
nausea,  vomiting,  dyspnoea  and  muscular  weakness.  The  toxic 
substance  of  poisonous  mussels  is  an  alkaloid  called  mytilotoxin ; 
but,  as  in  the  case  of  oysters,  the  symptoms  of  poisoning  may 
be  due  to  infection  or  intoxication  from  the  Gaertner,  paratyphoid, 
or  even  the  botuUnus  bacilli.  Such  mussels  generally  appear 
to  be  unhealthy,  with  large  livers.  Both  mussels  and  oysters, 
fed  in  sewage  polluted  water,  have  conveyed  the  infection  of 
enteric  fever. 


MEAT  353 

There  are  few  points  so  easy  to  detect  as  commencing  putridity 
in  fish;  this  is  fortmiate,  inasmucli  as  decomposition  sets  in 
rapidly,  and  appears  to  be  more  generally  productive  of  poisonous 
symptoms  than  decomposing  meat — the  symptoms  produced 
being  very  similar  in  both  cases.  The  bright  gills,  the  prominent 
eyes,  the  elastic  resistance  of  the  firmly  adherent  flesh,  and  the 
absence  of  any  but  the  characteristic  odour,  are  all  evidence  of 
freshness.  The  soft  inelastic  feel  of  the  fish,  and  the  unpleasant 
odour,  furnish  the  chief  clue — and  the  most  rehable — to  com- 
mencing decomposition;  since  it  is  possible  to  revive  the  gills  by 
artificial  colouring  agents,  and  to  keep  the  eyes  prominent  by  a 
small  piece  of  stick,  fixed  transversely  in  the  head,  so  that  it 
presses  the  eye  outwards  on  either  side. 

Meat  Extracts. 

Many  meat  extracts  are  now  upon  the  market,  the  tendency 
being  for  the  pubhc  to  over-estimate  their  food  value.  They 
consist  of  the  extractives  of  meat,  and  not  of  the  meat  itself; 
and  they  act  as  stimulants  and  regulators  of  digestion  rather  than 
as  true  foods  capable  of  providing  the  necessary  amount  of 
nitrogenous  material  for  the  needs  of  the  body. 

A  meat  extract  should  consist  of  a  golden-brown  sticky  sub- 
stance with  a  pleasant  meaty  odour.  It  should  never  be  hard, 
and  should  attract  moisture  strongly  from  the  air.  The  reaction 
should  be  slightly  acid.  The  usual  method  of  preparation 
consists  in  heating  raw  meat,  which  has  been  finely  divided,  with 
a  Httle  water  under  pressure.  The  extract  thus  made  is  filtered 
and  evaporated  in  vacuo  in  the  open.  It  is  essential  that  a 
temperature  below  75°  C.  be  employed  if  all  gelatine  is  to  be 
excluded  (Beveridge).  The  extract  thus  made  contains  the 
flesh  bases  or  extractives  and  mineral  matters  of  the  meat,  but 
is  free  from  albumin,  meat  fibre,  gelatine,  and  fat;  but  in  some 
of  the  meat  extracts  on  the  market  these  substances  and  also 
vegetables  are  subsequently  added  in  order  to  give  the  extract  a 
certain  food  value.  A  meat  essence  is  a  more  hquid  extract, 
containing  more  water,  but  has  the  same  colour,  odour,  and 
reaction.  Meat  juices  are  prepared  in  the  cold  by  subjecting 
finely  divided  meat  to  strong  pressure  and  ultimately  concen- 
trating by  evaporation  in  vacuo.  They  contain  the  soluble 
proteins  of  meat. 

These   substances,   prepared  as  above,   are  only  to   a  very 


354  HYGIENE   AND   PUBLIC   HEALTH 

limited  extent  foods  or  tissue-builders;  and  produce  neither  heat 
nor  energy.  They  are  chiefly  valuable  in  sickness  or  fatigue 
as  adjuvants  to  other  foods,  as  they  excite  the  flow  of  gastric 
juice,  aid  digestion,  and  increase  appetite.  Beveridge  gives  the 
analysis  of  a  well-known  meat  extract  as  follows:  Water,  37-2 
per  cent.;  mineral  matter,  22-2  per  cent.;  fat,  1-07  per  cent.; 
total  nitrogen,  7-1  per  cent. ;  equivalent  flesh  bases,  18-62  per  cent. 

Sausages. 

These  are  made  of  the  chopped  flesh  or  internal  organs  of 
various  animals,  mixed  with  condiments,  flour,  bread,  or  potato 
meal,  and  filled  into  clean  gut  or  parchment;  the  sausages  are 
then  generally  boiled,  smoked,  or  scalded.  Saltpetre  is  sometimes 
added  to  furnish  a  good  red  colour  to  the  meat,  and  often 
colouring  agents  (carmine,  cochineal,  or  aniline)  and  preservatives 
are  added.  The  colouring  matter  can  generally  be  extracted 
by  warming  for  several  hours  with  a  mixture  of  equal  parts  of 
glycerine  and  water.  Boric  acid  is  often  used  as  a  preservative. 
It  is  certain  that  since  boric  acid  prevents  objective  decom- 
position, such  as  is  detectable  by  odour,  it  permits  of  the  use  of 
stale  meat  and  meat  in  the  early  stages  of  decomposition  for  the 
making  of  sausages. 

While  the  amounts  of  boric  acid  usually  employed  will  not 
enable  the  use  of  meat  which  has  reached  a  stage  of  marked 
putrefaction,  they  permit  of  the  use  of  stale  material  in  a  state  of 
incipient  decomposition,  and  while  they  may  reduce  the  danger 
from  putrefactive  toxines,  they  do  not  materially  reduce  the  risks 
of  poisoning  from  organisms  of  the  Gaertner  group  or  from 
Bacillus  botulinus. 

Dr.  C.  A.  MacFadden,  in  a  Report  to  the  Local  Government 
Board  (1908),  expresses  the  view  that  if  on  the  ground  of  pubhc 
convenience  and  trade  requirements  the  use  of  chemical  anti- 
septics is  permitted  in  sausages,  it  appears  very  desirable  that 
their  employment  should  be  restricted  within  narrow  limits.  If 
boron  preparations  are  used  for  this  purpose,  he  suggests  that 
a  hmit  of  j  per  cent,  of  boric  acid  would  probably  be  ample,  and 
that  even  then  it  might  be  desirable  to  require  that  the  purchaser 
should  be  notified  of  the  presence  of  the  preservative. 

It  is  not  a  dillicult  matter  to  detect  early  decomposition  in 
sausages ;  the  alteration  in  the  odour  will  sometimes  suffice ; 
for  if  a  httle  of  the  sausage  is  boiled  with  water  and  some  freshly 


MILK 


355 


prepared  lime-water  is  added,  good  meat  yields  only  a  faint 
ammoniacal  odour,  whereas  bad  meat  will  give  off  a  peculiarly 
offensive  ammoniacal  odour.  Putrefaction  generally  commences 
in  the  middle  of  the  sausage,  when  a  dirty  greyish-green  colour  is 
often  to  be  noted. 

The  skins  of  sausages  have  been  known  to  contain  mineral 
poisons,  but  this  is  very  rare. 

Eggs. 

The  best  tests  for  bad  and  stale  eggs  are  the  following : 

1.  Fresh  eggs  are  most  transparent  towards  their  centres  if 
vertically  held  against  the  hght;  stale  eggs  are  transparent  at 
their  upper  extremities. 

2.  If  2  ounces  of  salt  are  dissolved  in  a  pint  of  water,  fresh 
eggs  when  placed  in  the  solution  sink,  and  stale  ones  float. 

Toxic  poison  has  been  separated  from  decomposing  eggs. 

Milk. 

Milk  is  the  natural  food  of  all  animals  belonging  to  the  Mam- 
malia for  a  longer  or  shorter  period  following  their  birth.  It 
therefore  contains  all  the  constituents  of  the  standard  diet,  and 
these  in  the  proportions  most  favourable  for  the  growth  and 
development  of  the  young  animal. 

The  varying  proportions  of  the  different  solid  constituents  of 
milk  as  secreted  by  the  human  female,  the  cow,  the  ewe,  the  goat, 
and  the  mare,  are  shown  in  the  following  table.     The  presump- 


AvERAGE  Percentage  Composition  by  Weight. 


Constituents. 

Cow. 

Mare. 

Goat. 

Ewe.  . 

Woman. 

Specific  gravity 

Fat   .... 
Caseinogen,  albumin, 

etc. 
Sugar 

Ash  .... 
Water 

1032-50 
3-76 

3-50 

4-75 
0-72 

87-27 

I036'I2 

1-76 

3-58 

5-87 

0-39 

88-40 

1032-70 
5-80 
4'20 

4.94 

I-OO 

84-06 

1039-30 

11-28 

8-83 

3-58 

1-09 

75-22 

1032-00 
3-14' 

2-53 

6-26 

0-32 

87-75 

Total 

100-00 

lOO-OO 

100 -OO 

100-00 

100-00 

tion  is  that  the  natural  milk  of  one  young  animal  is  not  suited  for 
the  nutrition  of  another  animal  of  a  different  species.    This  is  cer- 


356  HYGIENE   AND    PUBLIC   HEALTH 

tainly  true  of  the  human  infant,  which  thrives  far  better  on  human 
milk  than  on  cow's  milk.  In  cow's  milk  the  caseinogen  is  in  much 
too  large  a  proportion  as  compared  with  human  milk;  the  fat 
and  salts  are  also  in  excess,  whilst  the  milk  sugar  is  very  deficient. 

Two-thirds  of  the  proteid  of  human  milk  consists  of  lactal- 
bumin,  wliich  is  a  soluble  form  of  albumin  not  curdled  by  acids, 
and  coagulating  at  165°  F.  The  other  third  part  of  the  proteid 
of  human  milk  is  caseinogen,  which  is  an  insoluble  form  of 
albumin,^  and  forms  a  dense  curd  with  rennin  and  acids;  it  is  not 
coagulated  by  heat.  In  cow's  milk,  on  the  other  hand,  only 
about  one- tenth  part  of  the  proteid  is  in  the  form  of  lactalbumin, 
the  remainder  being  caseinogen  (see  p.  357). 

In  the  process  of  digestion,  milk  is  curdled  by  the  gastric 
juice;  the  caseinogen  and  fat  separate  as  curd,  whilst  the  sugar, 
the  soluble  albumins,  and  the  salts  remain  dissolved  in  the  water 
as  whey.  Owing  to  the  small  proportion  of  caseinogen  in  human 
milk,  the  curd  formed  in  the  stomach  is  a  loose  flocculent  mass, 
easy  of  digestion  and  assimilation;  whilst  cow's  milk,  owing  to 
the  abundance  of  caseinogen,  clots  in  putty-like  or  wet  cheese- 
like masses.  The  cow's  milk  curd  is  far  less  easily  digested;  it 
may  give  rise  to  dyspepsia,  flatulence,  and  diarrhoea,  and  some 
of  it  may  be  passed  unaltered  in  the  faeces.  Ass's  and  mare's 
milk  approximate  much  more  closely  in  composition  to  human 
milk,  and  give  a  loose,  flocculent  and  easily  digestible  curd. 
Goat's  milk  is  too  rich  in  fat  and  proteids,  but  it  also  forms  the 
proper  kind  of  curd  in  the  human  stomach,  and  the  circumstances 
that  her  excrement  is  solid  and  her  tail  short,  tend  to  favour  the 
cleanhness  of  the  milk. 

For  hand-fed  infants  under  nine  months  of  age,  if  cow's  milk 
is  used,  it  should  be  given  diluted  with  water,  and  milk  sugar 
should  be  added.  The  dense  clotting  may  be,  to  a  certain  extent, 
prevented  by  the  addition  of  some  mucilaginous  substance  to  the 
milk,  such  as  pearl  barley  water  well  boiled  and  strained,  which 
has  the  mechanical  effect  of  preventing  the  particles  of  casein 
coming  too  close  together;  and  the  curd  thus  formed  is  looser 
and  more  easily  attacked  by  the  digestive  juices. 

Wright  and  Poynton  have  shown  that  the  dense  clotting  of 
cow's  milk  with  rennet,  as  occurs  in  human  digestion,  may  be 
prevented  by  partial  removal  of  the  lime  salts  in  the  milk.      By 

1  Caseinogen  probably  exists  in  milk  in  combination  with  phosphate  of 
lime,  which  helps  to  keep  it  in  solution. 


MILK 


357 


adding  2  or  3  grains  of  citrate  of  soda  to  each  ounce  of  milk,  citrate 
of  lime  is  precipitated,  and  the  clot  which  rennet  produces  is  then 
much  Hghter  and  more  flocculent,  resembling  the  clot  formed  with 
human  milk. 

Humanized  cow's  milk  is  now  very  largely  used  in  the  feeding 
of  infants.  The  principle  to  be  observed  in  the  humanizing  pro- 
cess is  to  prepare  a  fluid  which  shall  have,  as  far  as  practicable. 

Human  Milk.  Cow's  Milk. 


ctxilbumen  0  3S 


Total  Solids,  12-27.  Total  Solids,  1273. 

Fig.  63. — Percentage  Composition  of  Solids  of  Human  and 
Cow's  Milk. 

the  composition  of  human  milk  so  far  as  the  chief  constituents 
are  concerned,  and  which  shall  also  be  devoid  of  harmful  organic 
life.  To  effect  this,  the  insoluble  caseinogen  of  cow's  milk  must 
be  reduced  to  the  proportion  present  in  human  milk,  the  lactose 
must  be  increased  to  the  right  proportion,  and  the  resulting 
mixture  must  be  Pasteurized.  Pasteurization  ensures  the  de- 
struction by  heat  of  the  pathogenic  organisms  which  are  liable  to 
get  into  milk,  but  does  not  sterilize  (destroy  all  organic  life). 


358  HYGIENE    AND   PUBLIC   HEALTH 

Sterilization  may  be  necessary,  if  the  milk  has  to  be  preserved 
for  any  length  of  time,  but  the  high  temperature  to  which  the 
milk  has  then  to  be  submitted  causes  coagulation  of  the  lactal- 
bumin,  with  the  result  that  the  milk  is  clotted,  and  loses  in  appear- 
ance. The  taste  of  the  milk  also  is  altered,  the  fine  emulsification 
of  the  fat  is  partly  destroyed,  a  partial  precipitation  of  calcium 
and  magnesium  salts  results,  and  the  caseinogen  is  hardened,  but 
smaller  clots  form  in  the  stomach  than  in  the  case  of  raw  milk. 

The  whey  cream  mixture  is  probably  the  simplest  and  most 
satisfactory  form  of  humanized  cow's  milk.  The  method  of 
preparing  this  mixture  is  as  follows:  A  pint  of  milk  is  allowed  to 
stand  in  a  cool  place  for  three  hours.  The  cream  which  has  risen 
to  the  top  is  then  separated  by  skimming.  The  skimmed  milk 
is  then  divided  into  two  equal  parts.  A  small  piece  of  rennet  is 
then  added  to  one  part,  and  the  curds,  when  formed,  are  strained 
off,  leaving  the  whey.  This  whey  is  heated  to  150°  F.  to  destroy 
the  rennet  ferment  remaining  in  it,  and  the  other  half  of  the 
skimmed  milk  and  the  cream  are  added  to  it.  Add  175  grains 
(3  drachms)  of  milk  sugar  (lactose)  to  the  mixture,  and  sufficient 
lime  water  to  render  very  faintly  alkaline.  Then  heat  to  158°  F. 
for  twenty  minutes. 

The  advantages  of  the  whey  cream  mixture  are  (i)  that  the 
excess  of  caseinogen  in  the  cow's  milk  is  removed,  whilst  the 
soluble  and  easily  digested  lactalbumin  is  retained.  (2)  The 
whey  makes  a  better  emulsion  with  the  fat  (cream)  than  water 
would,  and  jdelds  a  finer  curd. 

Koumiss  is  a  fermented  drink  prepared  from  mare's  milk  in 
Russia  and  Tartary ;  in  this  country  it  is  now  largely  made  from 
cow's  milk.  It  is  very  easily  digested  and  absorbed,  and  is  a 
valuable  food  for  invalids. 

All  the  solid  constituents  of  milk  are  dissolved  in  the  water 
of  the  milk,  with  the  exception  of  the  fat,  which  exists  as  innu- 
merable minute  globules  floating  freely  in  the  fluid. 

Cow's  Milk. 

The  average  milk  secretion  of  a  healthy  cow  may  be  taken  as 
20  to  25  pints  daily;  but  the  quantity  of  milk  and  its  richness 
in  solid  constituents  depend  largely  upon  breed  in  different  cows, 
and  in  the  same  cow  upon  its  age,  the  age  of  the  calf,  and  the 
season  of  the  year  as  influencing  its  food.  As  a  general  rule,  it 
may  be  stated  that  cow's  milk  should  not  have  less  than  12- 5  per 


MILK  359 

cent,  of  total  solids,  of  which  35  per  cent,  is  fat,  and  0-7  per  cent, 
is  salts;  the  specific  gravity  of  the  milk  being  about  1032,  and 
the  percentage  of  cream  by  volume  not  less  than  10  per  cent. 

To  make  up  the  standard  diet  for  an  adult  man,  of  23  ounces 
of  water- free  food,  about  9  pints  of  milk  must  be  consumed ; 
but  in  such  a  diet,  the  albuminoids,  the  fat,  and  the  water  would 
be  far  in  excess  of  the  requirements  of  the  system.  A  prolonged 
course  of  milk  diet— no  other  food  being  given — has  been  found 
exceedingly  useful  in  certain  forms  of  kidney  disease.  In  some 
cases  skimmed  milk  only  should  be  taken,  and  a  portion  of  the 
casein  should  be  separated  by  rennet  (a  preparation  from  the 
gastric  mucous  membrane  of  the  calf).  By  this  means  the  diet 
is  deprived  of  much  of  its  fat  and  albuminoids;  and  the  other 
constituents,  being  very  assimilable,  give  the  kidneys  little  work 
to  do  in  elimination,  whilst  the  water  clears  away  disease  products 
from  the  uriniferous  tubules  and  promotes  and  restores  healthy 
function. 

Many  persons,  from  constitutional  idiosyncrasy  or  weak 
digestion,  cannot  digest  milk.  If  the  milk  is  first  curdled  by  the 
addition  of  a  few  drops  of  acetic  acid  or  a  little  rennet,  and  the 
curds  and  whey  thus  formed  beaten  up  together,  and  a  little 
salt  and  pepper  added,  a  most  digestible  dish  is  prepared,  by 
reason  of  the  stomach  being  saved  the  operation  of  curdling, 
which  is  the  cause  of  the  disagreement. 

When  milk  is  allowed  to  stand,  some  70  per  cent,  of  the  cream 
rises  to  the  top  of  the  vessel  in  about  eight  hours.  A  centrifugal 
apparatus  is  now  largely  used  for  the  separation  of  cream ;  quite 
95  per  cent,  of  the  fat  being  removed  by  this  method.  Skimmed 
milk  generally  contains  about  i  per  cent,  of  fat ;  whereas  separated 
milk  generally  contains  less  than  0-3  per  cent.  Slightly  more 
fat  might  be  obtained  by  skimming  if  a  longer  period  were 
allowed  for  the  milk  to  stand;  but  after  a  time,  depending  upon 
the  temperature,  milk  undergoes  the  lactic  fermentation,  and 
becomes  markedly  acid,  the  sugar  being  converted  into  lactic 
acid  by  the  agency  of  certain  organisms,  which  grow  and  multi- 
ply in  the  milk.  The  milk  becomes  curdled,  and  the  whey 
separates  from  the  curd.  At  a  later  stage  lactic  acid  is  converted 
into  butyric  acid  by  means  of  another  bacterium  or  bacillus; 
the  milk  at  the  same  time  becomes  turbid,  and  putrefactive 
changes  set  in  from  the  growth  of  Bacterium  termo  and  other 
saprophytic  organisms. 


360  HYGIENE    AND   PUBLIC   HEALTH 

Sour  milk  has  been  advocated  for  the  treatment  of  intestinal 
dyspepsia.  The  organisms  which  break  down  lactose  into  lactic 
acid  appear  to  be  chiefly  of  two  kinds — the  bacillus  of  Massol,  or 
the  Bulgarian  bacillus  (Youghourt),  and  the  Streptococcus  lactidis. 
The  milk  is  first  sterilized  by  heat,  and  then  inoculated  with  a 
pure  culture  of  the  lactic  acid  bacilli,  the  milk  being  incubated  at 
37°  C.  for  several  hours,  until  sufficient  lactic  acid  is  formed.  In 
the  intestine  the  lactic  acid  bacilli  appear  to  have  the  property  of 
restraining  the  growth  of  the  organisms  which  cause  fermentation 
and  putrefaction,  whilst  they  themselves  are  harmless.  After  a 
time  a  growth  of  the  lactic  acid  bacilli  is  established  in  the  intes- 
tine, as  shown  by  the  appearance  of  these  organisms  in  the 
faeces.  Care  must  be  taken  to  thoroughly  sterilize  the  milk  in 
the  first  place,  and  subsequently  to  add  nothing  except  a  pure 
culture  of  lactic  acid  organisms,  otherwise  undesirable  fermenta- 
tions may  be  induced  causing  the  formation  of  toxic  products. 

Milk  may  be  sterilized,  and  thus  preserved  from  fermentation 
and  decomposition,  by  keeping  it  at  a  temperature  of  100°  C.  for 
fifteen  minutes  in  sterilized  vessels.  The  milk  is  then  raised  to 
a  boiling  temperature  and  hermetically  sealed.  A  closed  vessel 
should  be  used,  because  in  an  open  vessel  a  skin  forms  on  the 
surface  of  the  milk,  and  then  the  vitality  of  the  organisms  is  not 
so  readily  destroyed. 

Although  "  pasteurization  "  is  a  term  applied  to  denote  a 
procedure  the  details  of  which  may  vary  considerably,  it  may  be 
defined  as  the  exposure  of  milk  (previously  cleansed  by  filtration 
or  centrifugalization)  to  a  temperature  not  exceeding  70°  C.  for 
a  short  period;  and  then  rapidly  cooling  it  to  a  temperature  as 
much  below  15°  C.  as  possible.  Under  such  conditions  it  is 
possible  {a)  to  reduce  the  micro-organisms  which  are  capable  of 
being  cultivated  on  artificial  media  to  less  than  5  per  cent,  of 
those  which  can  be  cultivated  from  the  original  milk ;  to  thereby 
destroy  or  inhibit  the  fermentation  bacteria  so  as  to  delay  the 
natural  souring  of  the  milk  some  twelve  to  twenty-four  hours, 
the  milk  meanwhile  keeping  perfectly  wholesome;  {b)  to  destroy 
the  specific  organisms  of  tuberculosis,  diphtheria,  enteric  fever, 
cholera,  and  dj^sentery,  and  doubtless  also,  in  large  measure,  those 
organisms  that  are  causative  of  zymotic  diarrhoea.  It  is,  there- 
fore, a  valuable  measure  of  protection  against  the  recurrence  of 
those  milk-borne  epidemics  which  have  figured  in  the  epidemio- 
logical records  of  this  country;  it  is  a  useful  means  of  reducing 


MILK  361 

the  grave  risks  of  the  infection  of  tuberculosis  in  milk;  and 
the  evidence  is  overwhelming  that  it  reduces  the  suffering  and 
mortality  among  infants  who  are  artificially  fed  in  the  summer 
months. 

In  low  temperature  pasteurization,  which  is  advocated  by 
many,  the  milk  is  maintained  at  the  temperature  of  60°  C.  for 
thirty  minutes;  but  pasteurization  at  about  70°  C.  for  ten  to 
twenty  minutes  is  more  usual.  The  enzymes  in  milk,  which  are 
mostly  derived  from  bacteria,  and  are  probably  of  little,  if  any, 
value  to  the  infant,  are  not  destroyed  by  pasteurization  below 
66°  C.  for  thirty  minutes;  but  the  traces  of  anti-bodies  which 
exist  in  milk  (antitoxins,  opsonins,  agglutinins)  are  destroyed  at 
about  60°  C.  These  latter  bodies  also  appear  to  be  unimportant, 
for  they  are  not  absorbed  in  the  alimentary  canal,  but  rather 
destroyed  there.  Dr.  J.  Lane-Cla3^pon,  in  a  Report  to  the  J.ocal 
Government  Board  (1913),  finds  that  all  the  available  evidence 
in  this  and  other  countries  supports  the  view  that  the  boiling 
of  milk  in  no  wise  reduces  its  nutritive  value  to  the  young  animal. 

The  question  of  the  production  of  infantile  scurvy  by  the 
prolonged  use  of  sterilized  milk  has  received  much  attention. 
Where  the  condition  occurs  it  is  likely  to  be  due  either  to  the 
admixture  of  starchy  food  with  milk  or  to  the  use  of  stale 
sterilized  milk;  and  it  is  always  a  good  rule  where  an  infant  is 
brought  up  entirely  on  boiled  or  sterilized  milk  to  administer  daily 
a  small  quantity  of  grape,  orange,  or  lemon  juice,  so  as  to  make 
up  for  any  deficiency  in  the  antiscorbutic  principles  (vitamines  ?) 
in  raw  milk. 

For  trade  pasteurization,  which  has  for  its  object  the  improve- 
ment in  the  keeping  qualities  of  the  milk,  a  temperature  of  about 
70°  C.  is  usually  maintained  for  only  about  a  minute  or  even  less. 
Milk  is  also  preserved  in  a  desiccated  form  as  a  powder,  the 
water  being  expelled  by  evaporation ;  or  it  is  highly  concentrated, 
mixed  with  sugar,  and  then  sold  as  "  condensed  "  milk. 

Condensed  Milks. — ^The  table  on  p.  362,  taken  from  Dr.  Coutts' 
Report  to  the  Local  Government  Board  (191 1),  indicates  the 
percentage  chemical  composition  of  the  chief  classes  of  con- 
densed milk  on  the  market. 

As  a  rule  condensed  milks  are  free  from  preservatives.  In 
the  sweetened  milks  the  sugar  is  sufficient  to  inhibit  the  growth 
of  bacteria,  and  in  the  unsweetened  the.  milk  has  been  sterilized 
at  temperatures  over  100°  C.     The  processes  carried  out  in  con- 


362 


HYGIENE  AND  PUBLIC  HEALTH 


densing  the  milk  appear  to  be  sufficient  to  destroy  Bacillus  coli, 
B.  titberculosis,  and  other  pathogenic  organisms,  but  spore-bearing 


Full  Cream. 

Machine-Skimmed. 

Sweetened. 

Unsweetened. 

Sweetened. 

Lowest. 

Highest. 

Lowest. 

Highest. 

Lowest. 

Highest. 

Total  solids 
Protein 
Fat      . 
Lactose 
Ash      . 
Cane-sugar  . 

68-1 

7-3 
8-0 

II-6 
1-6 

36-1 

83-6 
1 1-4 
13-7 
17-6 
3-4 
44-6 

29-2 
8-0 
8-2 

II-I 

1-6 
Nil 

38-0 
lO'O 

11-9 
i6'0 

2-5 
Nil 

56-9 
7-6 
o-i 

iO'9 
1-6 

30-4 

79-1 
12-3 

I7-0 

2-9 

52-6     j 

baciUi,  streptococci,  sarcinae,  yeasts,  and  other  saprophj^tes,  are 
often  present,  so  that  condensed  milks  must  not  be  regarded  as 
necessarily  sterile.  It  is  probable  that  the  bulk  of  the  organisms 
present  have  gained  achnission  during  the  processes  of  cooling 
and  of  filling  the  tins. 

It  is  evident  from  the  above  table  that  the  full  cream  un- 
sweetened condensed  milk  is  the  one  most  suitable  for  the  feeding 
of  the  human  infant.  The  sweetened  milks  contain  cane-sugar, 
which  is  not  found  at  all  in  the  mother's  milk  of  the  human  infant ; 
and  the  large  amount  present  is  a  cause  of  the  fermentation, 
flatulence,  and  diarrhoea  so  common  in  infants  fed  on  these 
brands.  But  even  the  unsweetened  brand  is  defective  in  two 
important  qualities — namely,  (i)  that  the  original  enzymes  of 
the  fresh  milk  have  disappeared  in  the  processes  of  heating  and 
condensation,  and  (2)  there  is  a  loss  of  the  antiscorbutic  properties 
of  fresh  milk.  The  antiscorbutic  properties  of  fresh  milk  have 
intimate  relation  to  the  healthy  growth  and  nutrition  of  the 
infant,  even  if  the  enzymes  are  of  little  value. 

It  has  been  suggested  that  the  condensed  skimmed  milks 
should  be  compulsorily  labelled  "  Unfit  for  Infants."  The 
injurious  results  upon  many  infants  of  feeding  them  with  con- 
densed skimmed  milks  are  malnutrition,  resulting  in  emaciation 
and  atrophy,  or,  in  some  cases,  rickets  and  scurvy-rickets.  Many 
such  infants  die  before  their  first  year  is  completed  from  convul- 
sions, diarrhoea,  bronchitis,  and  pneumonia.  Those  which  sur- 
vive infancy  are  often  stunted,  ill-developed,  and  mentally  back- 

^  This  milk  was  only  partially  skimmed. 


MILK  363 

ward.  Enlarged  tonsils,  adenoids,  defective  formation  of  the 
jaws,  with  irregular  dentition,  and  all  the  evils  these  conditions 
give  rise  to,  are  undoubtedly  commoner  in  children  whose  diet 
has  been  deficient  in  fat,  and  relatively  much  too  rich  in  carbo- 
hydrates (cane-sugar),  than  in  those  whose  early  feeding  was  more 
in  consonance  with  physiological  requirements. 

In  recent  years  it  has  become  the  custom,  especially  in  the 
summer  months,  to  add  a  little  formalin,  or  boracic  acid  and 
borax  to  the  milk  as  a  preservative  against  fermentative  changes. 
Whatever  antiseptic  was  used,  it  was  consumed  with  the  milk  by 
the  customer,  and  adds  another  danger  to  the  already  long  cata- 
logue attributable  to  milk.  This  employment  of  agents,  termed 
antiseptics,  which  will  prevent  the  development  of  micro- 
organisms in  food,  is  now  prohibited  in  milk;  but  it  is  extensively 
practised  in  connection  with  other  foods.  The  antiseptics 
most  commonly  employed  in  different  kinds  of  food  are:  Borax 
and  boracic  acid,  salicylates,  benzoates,  formic  aldehyde  (used 
as  "  formalin,"  a  40  per  cent,  solution  of  formic  aldehyde), 
sodium  chloride,  and  vinegar;  but  saltpetre,  chloride  of 
ammonium,  sulphate  of  calcium,  alum,  spirits  of  wine,  sulphurous 
acid,  bisulphite  of  lime,  and  sulphate  of  copper,  have  all  been 
employed. 

There  is  no  doubt  that  the  unrestricted  use  of  these  agents 
should  be  condemned;  for  although  in  the  case  of  those  most 
commonly  employed  their  use  has  not  been  proved  to  cause  any 
direct  harm  to  consumers,  it  is  a  reasonable  belief  that  the  ignorant 
employment,  even  of  such  a  substance  as  boric  acid,  may  effect 
slight  and  indirect  injury  to  health,  and  is  capable  of  seriously 
interfering  with  digestion.  Dr.  H.  W.  Wiley,  of  the  United 
States  Department  of  Agriculture,  demonstrated  in  1905-7,  from 
feeding  experiments  upon  twelve  healthy  young  men,  that 
formic  aldehyde,  boric  acid  and  salicylic  acid  are  substances, 
which  when  added  to  food,  even  in  small  quantities,  may  exercise 
a  harmful  effect  on  digestion  and  health.  Few  of  these  agents 
enter  normally  into  the  constitution  of  the  human  body;  and 
at  least  they  must  be  regarded  as  foreign  bodies  whose  ingestion 
works  no  possible  good,  and  which,  not  being  foods,  do  not  in 
any  way  make  amends  for  the  additional  work  of  elimination 
which  their  presence  demands.  Moreover,  they  enable  vendors 
or  manufacturers  to  deal  with  stale  or  badly  prepared  food,  to 
the  prejudice  of  the  more  honest  tradesman.     If  the  adultera- 


364  HYGIENE    AND    PUBLIC   HEALTH 

tion  is  permitted,  the  vendor  should  at  least  be  compelled  to 
state  the  nature  and  amount  of  preservative  employed. 

Opinion  is  somewhat  divided  as  to  the  actual  harm  which 
results  from  the  use  of  very  small  quantities  of  preservatives  in 
food  ;•"■  but  the  use  of  such  agents  is  unnecessary ;  and  it  is  certain 
that  even  so  rapidly  decomposable  a  food  as  milk,  when  collected 
and  stored  with  proper  regard  to  cleanliness,  and  quickly  chilled, 
can  be  sufficiently  preserved,  even  in  the  hottest  weather,  to  meet 
all  the  requirements  of  its  distribution  and  use.  Food  purveyors 
have  very  little  knowledge  as  to  the  amount  of  preservative  it  is 
necessary  to  add,  and  there  is  nothing  to  prevent  such  an  article 
as  milk  from  being  dosed  more  than  once;  moreover  an  injurious 
quantity  of  preservative  may  easily  be  consumed  in  a  meal  which 
includes  a  number  of  foods,  in  each  of  which  there  is  only  a  small 
quantity  of  preservative.  The  practice  of  using  preservatives  in 
food  also  leads  to  uncleanly  treatment,  and  is  often  the  means 
employed  to  render  unwholesome  food  saleable.  In  several 
countries  preservatives  are  expressly  forbidden  by  law,  and 
successful  results  are  obtained  by  pasteurization,  sterilization, 
refrigeration  or  chilling.  The  Departmental  Committee  ap- 
pointed to  inquire  into  the  use  of  preservatives  and  colouring 
matters  in  food  in  the  year  1899,  recommended  the  prohibition  of 
the  use  of  formic  aldehyde,  and  that  salicylic  acid  should  not  be 
used  in  greater  proportion  than  i  grain  per  pint  in  hquid  food, 
and  I  grain  per  pound  in  sohd  food.  The  use  of  any  preservative 
and  colouring  agents  in  milk  was  condemned.  Certain  boron 
compounds  might  be  used  in  cream  and  butter  when  they  do  not 
exceed  025  per  cent,  and  05  per  cent,  of  boric  acid  in  cream  and 
butter  respectively.  They  found  that  no  preservatives  should 
be  used  in  any  invalid  or  infant  food,  and  that  copper  salts 
should  not  be  used  for  greening  preserved  fruits  and  vegetables. 
Experiments  have  shown  that  boric  acid  in  the  proportion  of 
20  grains  to  the  pound  prevents  objective  decomposition,  such 
as  is  detected  by  smell,  without  affecting  the  growth  of  coli 
organisms  or  Gaertner's  bacillus.  Its  employment  may  there- 
fore cloak  the  use  of  stale  meat  in  sausages  without  removing  or 
reducing  the  possibly  harmful  results  of  its  consumption. 

^  It  is  possible  that  the  "epidemic  eczema  or  dermatitis"  which  has 
been  observed  of  recent  years  in  various  metropoUtan  poor  law  infirmaries, 
and  which,  attacking  principally  inmates  of  advanced  age,  caused  in  some 
outbreaks  the  deaths  of  lo  per  cent,  of  those  attacked,  is  due  to  the  con- 
sumption of  milk  containing  formalin,  and  possibly  other  preservatives. 


MILK  365 

The  Public  Health  (Milk  and  Cream)  Regulations,  1912,  pro- 
hibit the  addition  of  all  preservatives  to  milk  intended  for  sale 
for  human  consumption.  They  also  prohibit  the  addition  of 
any  preservative  to  cream  containing  less  than  35  per  cent,  by 
weight  of  milk  fat.  To  cream  containing  more  than  35  per  cent, 
by  weight  of  milk  fat,  boric  acid  or  borax,  or  a  mixture  of  these, 
or  hydrogen  peroxide,  may  be  added,  but  the  vessel  containing 
the  cream  must  be  labelled ;  or  where  it  is  sold  for  consumption  on 
pubhc  premises,  printed  notices,  conspicuously  placed,  will  suffice. 

The  usual  preservative  for  cream  is  a  mixture  of  boric  acid  and 
borax  in  such  proportions  as  to  produce  a  nearly  neutral  solution. 
The  mixture  is  then  heated  to  expel  water,  and  finally  the  mass 
is  reduced  to  a  fine  powder.  A  small  quantity  of  saccharin  may 
be  added  to  mask  any  incipient  sourness.  Sodium  sahcylate  or 
sodium  benzoate  have  occasionally  been  added  to  reinforce  the 
preservative  effect  of  the  boric  acid,  but  these  are  no  longer 
allowed  under  the  Regulations  of  1912.  The  amount  of  boric 
acid  usually  present  in  preserved  cream  varies  a  good  deal.  No 
legal  limit  exists  ;  but  there  are  good  reasons  for  believing  that 
if  0-25  per  cent.  (17-5  grains  to  the  pound)  is  exceeded,  the  health 
of  infants  and  of  certain  invahds  may  be  injured.  This  amount  is 
sufficient  to  preserve  the  cream  from  fermentative  changes  for 
several  days — four  to  seven,  according  to  the  temperature  of 
the  air. 

Hydrogen  peroxide  is  used  as  follows : — The  cream,  immediately 
after  separation,  is  treated  at  120°  F.  with  the  peroxide,  100  c.c. 
of  a  3  per  cent,  solution  being  added  to  each  gallon  of  cream. 
The  mixture  is  maintained  at  120°  F.  for  ninety  minutes  in  a 
closed  vessel.  At  the  end  of  this  time  a  drop  or  two  of  a  solution 
of  catalase  is  added  to  each  gallon  of  cream  to  decompose  any 
remaining  peroxide. 

Cream  may  also  be  preserved  by  cold  storage,  and  by  steriliza- 
tion, i.e.,  by  exposure  to  a  temperature  of  212°  to  220°-  F.  lor 
about  half  an  hour.  Sterilized  cream  tends  to  separate  into  a 
watery  and  a  fatty  layer  on  keeping,  unless  it  has  been  passed 
through  an  homogenizer  previous  to  heating.  It  generally  has 
the  characteristic  taste  of  boiled  milk. 

The  Budde  process  for  the  preservation  of  milk,  the  invention  of  a 
Danish  engineer,  has  been  favourably  reported  on  by  Professor  Hewlett  in 
this  country.  In  this  process  peroxide  of  hydrogen,  in  the  proportion  of 
about  1 5  c.c.  of  a  3  per  cent,  solution  per  litre  of  milk,  is  added  to  the  milk, 
and  the  mixture  is  heated  to  52^  C.  for  at  least  three  hours.    A  temperature 


366 


HYGIENE  AND  PUBLIC  HEALTH 


below  48°  C.  is  not  sufficient,  and  one  above  55°  C.  should  be  avoided  as, 
this  may  induce  changes  in  the  physical  qualities  of  the  milk.  When  the 
milk  is  thus  heated,  the  peroxide  of  hydrogen  is  decomposed  into  water  and 
oxygen  by  an  enzyme  (catalase)  present  in  the  milk,  and  the  oxygen  being 
liberated  in  a  nascent  condition  acts  as  a  germicide.  At  the  end  of  the 
three  hours'  heating  the  whole  of  the  peroxide  of  hydrogen  should  have 
been  decomposed,  provided  the  right  proportion  has  been  added  to  the 
milk,  so  that  no  antiseptic  remains  behind  in  the  milk,  but  only  a  very 
small  addition  of  water.  The  heated  milk  should  be  immediately  bottled ; 
it  is  unaltered  in  appearance  and  flavour,  and  all  ordinary  non-sporing 
germs  having  been  destroyed  by  the  nascent  oxygen,  it  will  keep  fresh 
and  sweet  even  for  eight  to  ten  days  in  hot  weather. 

There  is  at  the  present  time  a  very  copious  literature  dealing 
with  the  diseases  and  injurious  effects  attributable  to  the  use 
of  cow's  milk.  Forming,  as  it  does,  so  large  a  proportion  of  the 
daily  food  of  infants,  young  children,  and  invalids  of  all  ages, 
and  consumed,  as  it  generally  is,  by  all  ages  and  all  classes,  in  an 


Fig.  64. — Aspergillus  Glaucus 
(x  about  150  diameters). 


Fig.  65. — Penicillium  Glaucum 
(x  about  200  diameters). 


uncooked  state,  the  importance  of  the  inquiries  that  have  been 
made  and  of  the  facts  that  have  been  elicited  can  hardly  be  over- 
estimated. The  following  considerations  will  be  found  of  use  in 
arriving  at  a  proper  understanding  of  the  subject. 

Milk  has  a  remarkable  power  of  absorbing  gases  and  vapours, 
organic  and  inorganic.  It  is,  besides,  a  fluid  which,  while  possess- 
ing all  the  essential  constituents  of  food,  forms  a  most  suitable 
cultivating  medium  for  low  forms  of  life,  fungoid  or  bacterial. 
So  that  it  is  not  too  much  to  assume  that  specific  disease  germs, 
which  have  gained  access  to  the  milk,  may  so  grow  and  multiply 
as  greatly  to  increase  its  power  of  infection. 

Under  natural  conditions  the  mother's  milk,  as  sucked  in  by 
the  infant,  is  free  from  all  organic  life;  but  where  cow's  milk  is 
substituted,  immense  numbers  of  living  germs  may  be  intro- 
duced into  the  stomach,  which  at  this  tender  age  may  be  unable 


MILK  367 

to  cope  with  them,  and  ill-health  and  disease  ensue.  These 
germs  gain  access  mainly  through  dirt,  and  a  bacterial  standard 
of  cleanliness  has  been  adopted  in  some  American  towns,  500,000 
per  c.c.  being  the  limit  of  organisms  permitted  in  raw  milk,  and  a 
limit  of  50,000  per  c.c.  has  been  adopted  for  pasteurized  milk. 
A  specially  produced  tubercle-free  "  certified  milk,"  as  sold  in 
America,  may  not  contain  more  than  10,000  micro-organisms 
per  c.c,  and  must  be  delivered  to  the  consumer  (who,  of  course, 
pays  a  much  higher  price  for  it)  at  a  temperature  not  exceeding 
10*=  C. 

The  chief  sources  of  the  infection  of  milk  are  dirt  and  water — 
dirt  finding  its  way  into  the  milk  during  and  after  milking, 
and  the  water  through  the  washing  of  the  cans,  or  by  wilful 
addition  to  the  milk  with  the  object  of  increasing  its  bulk. 

More  cleanly  methods  in  connection  with  the  collection, 
transit,  and  storage  of  milk  are  urgently  demanded.  It  has  been 
demonstrated  that  the  dirt  in  milk  chiefly  gains  access  at  the  farm, 
in  the  homes,  more  especially  of  the  poor,  and  to  a  less  extent 
during  transit.  It  has  not  yet  been  found  practicable  to  establish 
a  general  dirt  standard;  but  successful  prosecutions  have  been 
taken  under  the  sections  of  the  Public  Health  Act  which  deal 
with  unwholesome  food,  where  the  dirt  in  milk  has  been  found  to 
be  very  considerable.  In  order  to  reduce  the  amount  of  dirt  in 
milk  it  is  necessary  that  the  milker  should  have  clean  hands  and 
clean  overalls  at  the  time  of  milking;  that  he  should  perform 
"  dry  "  milking  into  sanitary  milk  pails  with  an  opening  not  ex- 
ceeding 8  inches  in  diameter;  and  that  the  cow  should  have  a 
clean  udder.  The  daily  grooming  of  cows  is  now  undertaken 
by  some  of  the  best  dairy  farmers;  the  chpping  of  the  hairs  on 
the  flanks,  round  the  udders,  the  hind  quarters,  and  the  tip  of 
the  tail  also  aids  in  protecting  the  milk  from  dirt.  Clean  bedding 
in  the  sheds  is  also  necessary.  Immediately  after  coUection  the 
milk  should  be  strained  through  a  fine  metal  gauze,  filtered 
through  a  layer  of  cotton- wool,  and  then  cooled  to  13"'  C,  or  as 
much  below  this  as  possible.  It  follows  that  all  utensils  must  be 
scrupulously  clean.  For  cleansing  purposes  steam  or  boiling 
water  is  essential.  In  railway  transit  the  milk  should  be  con- 
veyed in  sealed  dust-proof  cans;  and  in  the  home  it  should  always 
be  stored  in  clean  receptacles,  kept  cool  and  covered,  and  thus 
protected  from  the  access  of  dust  and  flies.  There  is  danger  in 
the  promiscuous  mixing  of  the  milk  from  different  farms,  as 


368 


HYGIENE   AND   PUBLIC   HEALTH 


practised  by  large  milk  dealers;  any  infection  in  the  milk  is  thus 
conveyed  to  a  wider  area  of  consumers  than  would  be  the  case  if 
this  practice  were  abandoned.  In  order  to  obtain  a  cleaner  and 
therefore  safer  public  milk  supply,  education  and  training  in  the 
hygiene  of  milk  collection,  storage  and  distribution,  is  demanded, 
and  the  general  public  must  be  taught  to  demand  clean  milk  and 
to  keep  it  clean,  for  the  poorer  section  of  the  public  permit  a  large 
amount  of  contamination  to  take  place  in  their  homes.  Sanitary 
authorities  are  doing  more  to  educate  the  general  public  on  matters 
affecting  the  public  health.  One  advantage  of  a  municipal  milk 
depot  or  model  dairy  is  the  opportunity  afforded  to  the  sanitary 
authority  of  presenting  an  object-lesson  to  the  local  milk  sellers 

of  a  model  dairy;  for  even  if  the 
farm  supplying  the  milk  is  not  a 
municipal  one,  the  local  authority 
can  usually  impose  what  conditions 
it  deems  necessary  upon  the  milk 
vendor  who  obtains  the  contract. 

Milk,  as  being  derived  from  the 
living  animal,  must  be  also,  to  a 
great  extent,  a  reflection  of  the 
animal's  state  of  health.  But  we 
can  go  further  than  this,  and  say 
that  milk  is,  for  a  certain  period, 
derived  from  an  animal  in  the 
puerperal  condition  consequent  on 
parturition  —  a  condition  known 
to  be  liable  to  certain  disorders, 
chiefly  inflammatory,  and  particularly  prone  to  take  the 
infection  of  contagious  disease. 

Milk  which  has  become  acid  from  lactic  and  coincidental 
fermentations  is  liable  to  cause  sickness  and  diarrhoea  in  children ; 
and  if  Oidium  albicans  is  present  in  the  milk,  it  may  attack  the 
mouth  and  digestive  tracts  of  infants,  causing  thrush.  Other 
fungi  and  moulds — penicillium,  aspergillus,  mucor,  etc.  (see 
pp.  366,  368) — when  present,  may  cause  severe  gastric  irritation. 
Similar  symptoms  have  been  produced  by  pus  and  fluids  from 
inflamed  udders  and  udder  abscesses  contaminating  the  milk. 

In  1881  Mr.  Ernest  Hart  compiled  tables  with  particulars  of 
50  epidemics  of  enteric  fever,  15  of  scarlet  fever,  and  6  of  diph- 
theria— 4,800  cases  of  infectious  disease  in  all — which  had  been 


Fig.  66. — Mucor  Mucedo 
(x  about  80  diameters). 


MILK  369 

traced  to  an  infective  or  a  supposed  infective  quality  of  the  milk 
supplies;  and  since  that  date  there  have  been  numerous  other 
milk  epidemics  recorded. 

In  the  case  of  enteric  fever,  the  most  usual  means  by  which 
milk  obtains  its  specifically  infectious  quality  is  the  washing  of 
the  milk  cans,  etc.,  or  the  intentional  dilution  of  the  milk,  with 
water  polluted  by  typhoid  dejecta.  In  other  cases  the  infection 
has  been  attributed  to  the  storage  of  milk  in  rooms  or  dairies 
the  air  of  which  was  subject  to  drain  or  sewer  emanations;  but 
probably  the  most  frequent  cause  of  milk  obtaining  infective 
power  is  the  presence  of  a  person  in  the  milk  shed  or  dairy  who  is  a 
"  typhoid  carrier."  The  handhng  of  the  teats  of  the  cow  or  of 
the  milk  vessels  by  hands  tainted  with  infected  excreta  (not 
properly  cleansed  after  attending  to  the  calls  of  nature) ,  is  a  very 
obvious  means  by  which  the  milk  receives  a  massive  infection. 
Kober,  in  1901,  pubhshed  the  facts  of  195  milk  epidemics  of 
enteric  fever,  in  148  of  which  the  infection  was  ascribed  to  in- 
sanitary farm  conditions.  There  is  no  evidence  that  enteric 
fever  is  a  disease  of  cattle  communicable  to  man  through  the  milk 
secretion,  or  by  means  of  pollution  of  the  milk  by  the  alvine 
discharges  through  careless  milking. 

In  those  epidemics  of  scarlet  fever  which  have  been  traced  to 
milk,  it  has  been  usual  to  find  that  the  milk  was  infected  through 
human  agency  by  a  previous  case  of  the  disease  at  farm  or  dairy. 
The  cows  were  milked  by  a  person  who  was  attending  on  a 
scarlet  fever  patient,  who  had  the  disease  amongst  his  family — 
possibly  in  an  unrecognized  form,  as  sore  throat  without  rash — 
or  who  was  himself  suffering  from  it  in  a  mild  or  disguised  form. 
Occasionally  the  milk  appears  to  have  derived  its  infective 
quality  from  being  kept  in  a  room  in  which  clothes  or  refuse 
matters  from  the  sick  were  lying. 

But  besides  such  easily  understood  methods,  the  history  of 
the  Hendon,  Wimbledon,  and  Wiltshire  (1909)  outbreaks  ap- 
peared to  show  that  cows  are  liable  to  a  disease  identical  with 
or  very  closely  resembling  human  scarlet  fever,  and  that  the 
milk  from  animals  so  suffering  might  prove  to  be  the  cause  of 
epidemic  outbursts  of  the  disease  amongst  those  who  consumed 
it.  Dr.  Klein  isolated  an  organism — a  streptococcus — from  the 
udder  lesions  (ulcers)  on  the  Hendon  cows,  which  he  believed  to 
be  the  true  pathogenic  organism.     A  streptococcus  has  also  been 

found  in  the  diseased  organs  and  tissues  of  human  scarlatinal  cases. 

24 


370  HYGIENE    AND    PUBLIC   HEALTH 

Subcultures  of  this  organism  obtained  from  human  scarlatinal 
cases,  when  inoculated  into  recently  calved  cows,  are  said  to 
produce  the  characteristic  ulcers  on  the  teats,  along  with  other 
manifestations  of  the  Hendon  cow  disease;  and  calves  fed  on 
these  subcultures  obtain  the  same  disease.  This  matter  has  been, 
however,  and  still  is,  the  subject  of  much  controversy.  The 
opponents  (including  nearly  all  the  members  of  the  veterinary 
profession)  of  the  views  of  Dr.  Klein  and  of  Mr.  Power,  who 
investigated  the  Hendon  outbreak,  hold  that  a  possible  human 
source  of  the  disease  at  Hendon  was  not  absolutely  excluded,  and 
assert  that  other  cows  suffering  from  the  Hendon  disease  have 
not  given  rise  to  any  scarlet  fever  outbreak.  The  weight  of 
opinion  is  opposed  to  the  view  that  cows  are  capable  of  imparting 
the  infection  of  scarlet  fever  to  their  milk. 

In  the  most  recent  instance  of  a  scarlet  fever  epidemic  being 
apparently  due  to  a  cow  disease,  in  which  parts  of  London  and 
its  south-western  suburbs  were  extensively  invaded  in  June, 
1909,  it  was  not  possible  definitely  to  exclude  a  human  source 
of  infection;  but  the  Hendon  disease  was  undoubtedly  present 
in  several  of  the  cows  on  the  Wiltshire  farm  which  supplied  the 
milk,  just  anterior  to  the  onset  of  the  first  cases. 

A  possible  explanation  of  the  association  of  scarlet  fever  in 
human  beings  with  the  milk  of  cows  that  have  ulcerated  teats 
lies  in  the  supposition  that  whilst  the  ordinary  ulcer  on  the  teat 
is  a  cow  complaint,  which  has  no  relation  at  all  to  scarlet  fever, 
such  an  ulcer  may  become  inoculated  by  the  scarlatinal  virus  in 
the  process  of  milking  by  a  person  who  is  suffering  in  a  mild, 
unrecognized  form  from  that  disease.  The  ulcerations  may 
provide  a  nidus  for  the  growth  of  the  scarlatinal  organism,  and 
give  the  milk  an  infective  power  owing  to  the  ulcerated  surfaces 
being  handled  during  milking.  This  would  account  for  the  fact 
that,  whilst  in  the  great  majority  of  instances  cows  with  ulcerated 
teats  yield  a  milk  which  causes  no  disease,  in  very  occasional 
instances  such  cows  seem  to  5deld  a  milk  which  has  the  capacity 
to  produce  scarlet  fever. 

In  a  large  percentage  of  the  milk  epidemics  of  diphtheria,  it 
has  not  been  possible  to  trace  the  source  from  which  the  milk 
derived  its  infective  quality.  This  is  not  to  be  wondered  at ;  for 
shght  cases  of  diphtheria  are  very  difficult  to  trace,  the  diph- 
theritic character  of  a  sore  throat  not  being  always  recognizable 
even  to  a  medical  attendant.    There  is  practically  no  evidence  to 


MILK  371 

show  that  diphtheria  may  be  a  cow  disease  transmissible  to 
human  beings,  altliough  calves  have  been  known  to  suffer  from 
a  throat  affection  presenting  post-mortem  appearances  very 
similar  to  those  found  in  human  diphtheria.  The  question  as  to 
whether  garget  or  mammitis  in  cows  is  capable  of  producing 
diphtheria  in  the  consumers  of  milk  taken  from  gargety  udders 
may  be  answered  in  the  negative,  but  there  is  some  evidence 
to  show  that  it  may  be  responsible  for  outbreaks  of  septic  sore 
throat.  It  is  possible  that  here  again  the  infection  may  have  a 
human  origin. 

Recent  experiments  of  Savage,  however  (L.  G.  B.  Report, 
1908-9),  tend  to  show  that  the  common  organism  of  mastitis 
in  cows — the  Streptococcus  mastitidis — is  not  a  cause  of  human 
sore  throat  or  other  human  illness. 

Stall-fed  dairy  cows  in  towns  are  very  susceptible  to  tubercle. 
Veterinary  authorities  have  stated  that  at  least  25  per  cent,  of 
all  dairy  cows  kept  in  cowsheds  are  the  subjects  of  this  malady. 
These  animals  are  stalled  day  and  night  in  stables  often  uncleanly 
and  badly  ventilated,  and  they  are  perpetually  being  drained  of 
large  quantities  of  milk.  Prolonged  lactation  in  the  human 
female  is  well  known  to  be  a  frequent  precursor  of  phthisis;  and 
it  is  not  wonderful  that  under  such  circumstances,  and  with  the 
additional  factors  of  confinement,  want  of  exercise  and  bad 
air,  cows  should  succumb  to  a  malady  to  which  they  are  in  a  high 
degree  susceptible.  It  often  happens  that  the  best  bred  animals, 
which  are  usually  the  best  milkers,  are  those  which  are  most 
affected.  In  the  early  stages  the  symptoms  of  the  disease  are  ill 
defined,  the  health  of  the  animal  is  not  much  interfered  with, 
and  the  milk  secretion  is  as  abundant  as  ever.  Nutrition  is  not 
interfered  with  until  the  disease  is  well  advanced,  and  even  then 
the  amount  of  milk  yielded,  although  poor  in  quality,  may  not  be 
diminished,  and  the  dairy  farmer  continues  to  keep  the  animal 
in  stock. 

From  the  Third  Report  of  the  Royal  Commission  on  Tubercu- 
losis it  appears  that  the  milk  of  cows  obviously  suffering  from 
tuberculosis  frequently  contains  tubercle  baciUi,  even  although 
no  disease  is  present  in  the  udders.  By  "  obviously  suffering  " 
is  meant  the  display  of  clinical  symptoms  of  disease,  not  merely 
a  reaction  to  tuberculin.  It  is,  however,  generally  recognized  that 
the  liability  of  the  milk  to  contain  tubercle  bacilli  is  far  the  greatest 
when  one  or  more  quarters  of  the  udder  have  become  tubercular. 


372  HYGIENE    AND   PUBLIC   HEALTH 

Tuberculosis  of  the  udder  may  be  suspected  when,  as  a  result 
of  inspection  and  palpation  of  the  udder  (empt}^  of  milk),  certain 
of  its  parts  are  found  to  be  hard  or  enlarged.  The  healthy 
udder,  when  empty  of  milk,  feels  uniformly  soft,  and  shows  no 
asymmetrical  enlargements.  To  confirm  the  diagnosis,  it  will 
be  necessary  to  draw  off  (with  aseptic  precautions)  some  of  the 
milk  from  each  of  the  four  teats,  and  submit  each  sample  to 
bacteriological  examination. 

The  milk  of  tubercular  cows  which  have  no  udder  affection 
may  become  contaminated  from  the  alvine  discharges,  when  the 
cows  are  not  kept  clean  in  their  stalls  or  are  carelessly  milked, 
as  it  has  been  ascertained  that  in  cows  presenting  clinical  symp- 
toms of  the  disease  the  faeces  often  contain  large  numbers  of 
living  and  virulent  tubercle  bacilli.  The  sheds  are  also  infected 
by  the  coughing  of  tubercular  cows — or  even  by  a  milker  suffering 
from  phthisis. 

In  every  dairy  farm  of  any  size,  where  no  special  precautions 
are  taken  to  control  the  spread  of  tuberculosis,  there  will  prob- 
ably be  tuberculous  cows,  some  of  them  most  likely  with  tuber- 
culous udders;  and  as  it  is  the  common  custom  of  dairymen  to 
mix  together  the  milk  jdelded  by  different  cows,  it  is  not  too 
much  to  assume  that  tubercle  bacilli  may  be  widely  distributed 
in  the  milk  supply.  As  a  matter  of  fact,  the  bacilli  have  been 
found  by  many  observers  in  some  lo  per  cent,  of  the  dairj' 
samples  examined  by  them. 

The  bacilli  of  bovine  tuberculosis  are  practically  identical — 
according  to  all  bacteriological  methods  at  present  known — 
with  those  found  in  tubercular  formations  in  the  human  organs, 
although  the  disease  presents  anatomical  differences  in  man  and 
cattle.  But  these  differences  are  probably  due  to  differences  of 
soil  in  the  human  and  bovine  tissues,  the  bacilli  engrafting  them- 
selves in  those  tissues  which  present  conditions  most  favourable 
to  their  growth  and  development. 

The  human  bacillus  differs  from  the  bovine  bacillus  in  that 
it  is  longer,  thinner,  and  grows  more  luxuriantly;  it  is  also  of 
relatively  lower  virulence.  There  are,  however,  connecting 
forms  which  clearly  indicate  that  these  two  types  belong  to  the 
same  species,  and  that  these  differences  are  merely  modifications 
of  their  characters.  The  bovine  bacillus  produces  by  feeding 
or  inoculation  the  typical  tuberculosis  lesion  in  many  animals 
other  than  the  bovine;  this  is  true  even  of  monkeys  and  anthro- 


MILK  373 

poid  apes.  The  human  bacillus  produces  the  typical  tuberculosis 
lesion  in  several  animals — e.g.,  the  guinea-pig  and  monkeys.  It 
can  infect  bovines,  though  usually  in  a  limited  retrogressive  form. 
In  a  certain  small  proportion  of  the  cases  of  human  tuberculosis 
the  bacillus  is  the  bacillus  of  bovine  tuberculosis,  in  all  respects 
identical  and  indistinguishable  from  those  bacilli  taken  from  a 
pure  bovine  source. 

From  post-mortem  examinations  it  appears  that  in  25  per  cent, 
of  all  human  tuberculosis  cases  under  five  years  of  age,  and  in 
over  40  per  cent,  of  abdominal,  gland,  and  joint  tuberculosis 
during  this  age  period,  the  bovine  species  of  germ  is  present. 
This  being  so,  a  considerable  amount  of  tubercular  infection 
through  milk  must  take  place  in  infancy  and  early  childhood. 

The  autopsies  of  young  children  show  that  primary  tubercular 
intestinal  ulceration  of  the  intestines  is  very  rare ;  it  is,  however, 
quite  possible  that  in  children  tubercle  bacilli  may  pass  through 
the  intestinal  mucosa  and  the  mesenteric  glands,  and  thence 
invade  even  the  bronchial  glands  and  the  lungs,  leaving  little  or 
no  trace  of  their  passage  in  the  intestines  or  abdominal  glands. 
What  appears,  then,  to  be  a  primary  deposit  in  the  chest  may  in 
reality  have  been  due  to  an  infection  introduced  into  the  alimen- 
tary canal  by  means  of  food.  But  it  is  a  noteworthy  fact  that 
the  deaths  from  abdominal  tuberculosis  during  recent  years  have 
shown  a  greater  reduction  than  those  from  all  other  forms  of  the 
disease.  Moreover,  whilst  the  children  of  the  poor  are  the  most 
notable  sufferers  from  tabes  mesenterica,  they  are  not  nearly  such 
large  consumers  of  milk  as  the  children  of  those  higher  in  the 
social  scale,  who  suffer  much  less  from  this  and  other  complaints 
suggestive  of  abdominal  tuberculosis. 

It  is  quite  possible  that  any  excess  of  abdominal  tubercle 
amongst  the  children  of  the  poor,  if  there  is  such  an  excess,  is  due 
to  infection  from  human  sources,  the  children  contracting  tubercle 
from  being  allowed  to  crawl  about  dirty,  dusty  rooms,  infecting 
their  mouths  from  their  fingers  and  from  dirty  rubber  bottle 
teats. 

Evidence  obtained  by  Delepine  shows  that  bovine  tuberculosis 
is,  on  an  average,  more  prevalent  in  districts  where  shippons 
are  generally  in  a  bad  state,  small,  or  badly  ventilated  and  dirty; 
and  where  also  it  is  the  usual  practice  to  retain  many  aged  cows 
on  the  farms. 

In  order  to  materially  reduce  the  dangers  arising  from  the  con- 


374  HYGIENE   AND   PUBLIC   HEALTH 

sumption  of  the  milk  of  tuberculous  cows,  the  following  are 
measures  which  have  been  suggested  and  in  some  cases  adopted : 

1.  A  quarterly  veterinary  inspection  of  all  cows  the  milk  of 
which  is  being  sold  or  offered  for  sale  for  human  consumption; 
and  power  to  collect  samples  of  milk  for  bacteriological  examina- 
tion. 

2.  The  isolation  from  other  milch  cows  of  those  suffering  from 
"  open  "  tuberculosis,  or  showing  clinical  symptoms  of  tubercu- 
losis; the  branding  of  such  cows,  and  the  prohibition  by  law  of 
the  sale  of  their  milk  for  human  consumption,  or  for  the  feeding 
of  other  animals  unless  effectively  sterilized. 

3.  The  making  of  diagnosable  tuberculosis  a  notifiable  disease 
in  the  case  of  milch  cows. 

4.  The  compulsory  notification  of  all  forms  of  udder  disease 
in  milch  cows,  and  the  prohibition  of  the  sale  of  milk  in  these 
cases,  except  on  a  veterinary  certificate  to  the  effect  that  the 
disease  is  not  of  a  character  likely  to  affect  the  wholesomeness  of 
the  milk. 

In  order  to  eradicate  bovine  tuberculosis  the  following  sugges- 
tions have  been  favoured: 

1.  The  provision  of  open-air  sheds.  It  has  already  been 
demonstrated  by  actual  experiment  that  the  cows  are  in  a 
decidedly  better  condition  by  being  kept  more  in  the  open,  and 
that  their  coats  become  thicker,  while  the  milk  does  not  decrease 
in  amount. 

2.  Quarterly  inspections  and  tubercuUn  tests  every  six  months. 
The  slaughter  of  all  infected  bovines.  Partial  compensation. 
A  system  of  mutual  assurance  amongst  farmers  is  advocated, 
to  reduce  the  loss  involved  in  compensation. 

3.  Some  useful  results  appear  to  have  been  obtained  from 
efforts  to  render  bovines  immune  to  the  disease,  as  by  Behring's 
vaccination,  but  the  immunity  disappears  within  two  years, 
and  it  has  been  shown  that  the  human  tubercle  germ  employed 
may  find  its  way  into  the  milk  within  twenty-four  hours,  and 
continue  to  be  present  in  the  cow's  milk  for  months.  The  value 
of  tuberculin  appears  to  be  limited  to  the  diagnosis  of  the  disease, 
in  bovines. 

The  system  of  eradication  recommended  by  Professor  Bang 
includes  a  testing  of  herds  in  the  spring  and  autumn  of  each 
year  with  tuberculin;  the  segregation  of  those  which  react,  and 
disinfection  of  infected  sheds;  "  wasters  "  and  cows  with  tubercu- 


MILK  375 

losis  of  the  udder  to  be  dried  off  and  sold  for  slaughter,  and  the 
selection  of  the  tuberculosis-free  cow  for  calf-rearing. 

By  Ostertag's  scheme  only  cases  of  "  open  "  tuberculosis — 
namely,  those  bo  vines  discharging  tubercle  bacilli — are  segre- 
gated and  slaughtered.  This  method,  while  reducing  milk 
infection,  cannot  eliminate  tuberculosis. 

Foot  and  mouth  disease,  or  epizotoic  eczema,  is  a^contagious 
disease,  characterized,  in  cows,  by  an  eruption  of  small  vesicles 
on  the  lining  membrane  of  the  mouth  and  the  interdigital  spaces 
of  the  feet;  not  infrequently  the  vesicles  appear  on  the  udders 
and  teats.  In  the  majority  of  cases  the  milk  secretion  is  dimin- 
ished as  the  disease  progresses,  and  may  become  entirely  sus- 
pended. The  fever  runs  its  course  in  from  eight  to  fifteen  days. 
The  contagion  exists  in  its  most  concentrated  form  in  the  lymph 
or  serum  of  the  vesicles  (those  on  the  teats  are  liable  to  be  rup- 
tured in  milking)  and  in  the  saliva,  and  it  possesses  considerable 
vitality. 

Numerous  outbreaks  among  human  beings  of  a  peculiar  illness 
have  been  traced  to  the  use  of  milk  from  cows  with  this  disease. 
The  symptoms  are  generally  slight  fever,  vesicular  eruptions  on 
the  throat  and  lips,  swelhng  of  the  tongue,  salivation,  nausea, 
foetor  of  breath,  pain  in  limbs,  and  marked  swelling  of  the  lym- 
phatic glands  of  the  neck.  It  is  probable  that  the  transmission 
of  the  disease  is  most  certain  in  those  cases  where  there  are 
vesicles  on  the  cow's  teats,  which  are  sure  to  be  ruptured  in 
milking,  the  virus  thus  obtaining  direct  access  to  the  milk. 

Goat's  milk  has  been  shown  to  be  one  of  the  chief  channels  of 
the  infection  of  Malta  fever. 

In  the  case  of  cows  suffering  from  cattle  plague  and  anthrax, 
the  milk  secretion  is  suspended  at  a  very  early  stage.  In  cow-pox 
the  milk  secretion  is  said  to  be  rapidly  diminished  or  suppressed. 

A  milk  epidemic  is  characterized  by  the  suddenness  with  which 
it  makes  its  appearance,  the  sufferers  being  for  the  most  part 
attacked  about  the  same  time.  The  infected  houses  will  be 
found  to  have  been  supplied,  with  a  few  exceptions,  by  the 
particular  milk  vendor  whose  supply  is  at  fault.  Where  infected 
houses  are  discovered  to  which  milk  has  been  supplied  from 
different  vendors,  this  circumstance  is  often  due  to  the  fact  that 
the  vendors  on  their  rounds  very  commonly  buy  small  quantities 
of  milk  from  each  other. 

The  cases  are,  of  course,  localized  to  the  area  of  distribu- 


376  HYGIENE   AND    PUBLIC   HEALTH 

tion  of  the  infected  milk  supply;  women  and  children  in  the 
better  class  houses  are  mostly  attacked,  and  the  drinkers  of  raw 
milk  are  often  picked  out.  Generally  speaking,  incubation 
periods  are  shortened,  attacks  are  mild,  the  mortality  rate  is 
lower  than  usual,  and  the  epidemic  often  ends  rapidly. 

Sometimes  valuable  corroborative  testimony  implicating  the 
milk  is  forthcoming  in  the  circumstance  that  some  of  those  in 
the  infected  households,  who  have  consumed  no  unboiled  milk, 
have  escaped;  and  that  households  supplied  from  the  implicated 
dairy,  but  in  which  no  unboiled  milk  is  consumed  at  all,  have 
entirely  escaped. 

In  several  towns  in  England  and  on  the  Continent  municipal 
depots  have  been  established  for  the  distribution  of  humanized 
(sterilized)  milk ;  and  it  is  claimed  that  these  have  had  a  beneficial 
effect  in  reducing  infantile  mortality.  Good  cow's  milk  is 
diluted  and  cream  and  sugar  added.  The  humanized  milk  is 
then  placed  in  small  stoppered  bottles  of  some  five  ounces 
capacity  and  placed  in  the  sterilizer.  The  bottles  are  kept 
exposed  to  a  temperature  of  102°  C.  in  a  steam  sterilizer  for  about 
45  minutes,  and  they  are  then  taken  out  and  placed  in  baskets. 
The  quantity  of  the  milk  is  adjusted  according  to  the  age  of  the 
child,  and  before  use  each  bottle  should  be  placed  in  a  little  hot 
water,  the  stopper  removed,  and  a  teat  fitted  to  the  bottle  direct. 
The  parents  are  general^  charged  is.  6d.  per  week;  but  this  does 
not  meet  all  the  expenses  in  connection  with  the  depot.  Such 
institutions  are  of  limited  value  unless  they  are  also  made  the 
centres  from  which  many  well-informed  workers  issue  to  instruct 
and  advise  upon  how  to  prepare,  and  guard  the  purity  of  the 
milk  used  for  infant  feeding  in  the  home  itself. 

Dried  milk  as  a  food  for  infants  has  been  favourably  spoken  of 
by  Dr.  Millard,  Medical  Officer  of  Health  of  Leicester.  In  the 
process  of  manufacture  fresh  milk  is  fed  in  a  continuous  stream 
on  to  revolving  heated  cylinders  on  which  it  forms  thin  films. 
The  cylinders  are  heated  by  steam  at  about  40  pounds  pressure 
(250°  F.),  and  the  moisture  of  the  milk  is  thus  evaporated.  The 
dried  films  are  automatically  detached  from  the  cylinders  by 
knife-edges,  and  subsequently  sieved  and  pulverized.  The  result 
is  a  coarse,  granular  powder,  practically  sterile,  which  in  air- 
tight packages  will  keep  good  for  a  long  period.  For  use,  the 
milk  powder  is  mixed  with  an  equivalent  quantity  of  water. 
The  fluid  thus  formed  is  found  to  be  digestible  by  infants,  prob- 


MILK  377 

ably  owing  to  the  fact  that  the  curd  formed  in  the  stomach  is  not 
dense,  Hke  the  ordinary  cow's  milk  curd.  To  prevent  scurvy  the 
routine  administration  of  fresh  fruit-juice  is  advised.  At  the 
present  time  at  the  Leicester  Infants'  Milk  Depot  dried  milk  has 
almost  entirely  superseded  the  "  humanized  "  milk,  as  it  is 
found  less  costly  than  the  latter  system,  where  so  much  labour 
is  spent  on  bottling  the  "  separate  "  feeds  and  cleansing  the 
bottles,  and  equally  satisfactory  from  the  health  aspect. 

The  Board  of  Agriculture  has  fixed  certain  low  limits  (stand- 
ards) with  reference  to  the  composition  of  milk  under  the  Sale 
of  Milk  Regulations,  1901.  The  fat  must  be  not  less  than  3  per 
cent.,  and  the  non-fatty  solids  must  reach  8-5  per  cent.  It  shall 
be  presumed  that  the  milk  is  not  genuine  if  these  limits,  or  one 
of  them,  is  not  reached.  Under  the  Sale  of  Milk  Regulations, 
1912,  where  a  sample  of  skimmed  or  separated  milk  (not  being 
condensed  milk)  contains  less  than  87  per  cent,  of  milk  solids 
other  than  milk  fat,  it  shall  be  presumed  that  the  sample  is  not 
genuine. 

Butter. 

When  the  cream  of  milk  is  churned — i.e.,  violently  agitated  in 
a  suitable  apparatus — the  fat  globules  coalesce,  entangling  in 
their  meshes  some  casein  and  serum.  The  butter  so  formed  is 
then  pressed  to  squeeze  out  some  of  the  moisture,  and  salt  added 
to  preserve  it.  The  percentage  proportions  of  the  constituents 
of  butter  are  approximately  as  follows: 

Fat 83-5 

Curd 1-0 

Ash 1-5 

Milk-sugar i-o 

Water 13-0 

The  amount  of  water  in  a  sample  of  butter  should  never  be 
more  than  16  percent,  by  weight,  and  the  fat  should  constitute 
at  least  80  per  cent. 

The  fat  of  butter  consists  of  a  mixture  of  the  glycerides  of  the 
fatty  acids — palmitic,  stearic,  and  oleic — ^not  soluble  in  water; 
and  also  of  the  glycerides  of  certain  soluble  and  volatile  fatty 
acids,  principally  butyric. 

Margarine,  oleo-margarine,  or  butterine,  is  manufactured  from 
animal  fats  (lard,  beef,  and  mutton  fats),  and  vegetable  oils 
(cotton  seed,  sesame,  earth  nut,  etc.).  When  made  from  beef  fat, 
this  is  first  finely  minced  and  heated  in  tanks  to  about  39"  C. 


378  HYGIENE   AND   PUBLIC  HEALTH 

The  fat  then  melts,  and  the  water  and  debris  sink  to  the  bottom. 
The  melted  fat  is  run  off  as  a  clear  yellow  oil,  and  kept  at  a  tem- 
perature of  about  30°  C.  The  stearin  to  a  certain  extent  solidifies 
at  this  temperature,  whilst  the  oleo-margarine  is  separated  as 
a  liquid,  from  which  much  of  the  stearin  has  been  removed; 
for  oleo-margarine  solidifies  at  a  much  lower  temperature  than 
stearin.  The  oleo-margarine  is  then  filtered,  pressed,  churned 
up  with  milk  to  give  it  the  flavour  of  butter,  coloured  with 
annatto,  and  cooled  with  ice,  when  it  is  ready  for  sale. 

The  great  distinction  between  butter  fat  and  margarine  fat 
lies  in  the  fact  that  the  butter  fat  contains  nearly  8  per  cent,  of 
the  volatile  fats,  whilst  the  margarine  fat  has  rarely  more  than 
I  per  cent.  In  the  analysis  of  these  substances  this  difference 
is  made  use  of.  The  same  antiseptic  and  colouring  agents  are 
employed  in  butter  as  in  milk. 

Margarine  is  but  little  inferior  in  nutritive  qualities  to  butter; 
it  constitutes  a  good  article  of  diet — but  it  must  not  be  sold 
as  butter.  It  is  somewhat  less  digestible  than  butter,  and 
much  more  generally  contains  colouring  agents  and  preservatives. 

Cheese. 

Cheese  is  an  easily  digested  and  most  nutritious  article  of  diet. 

In  the  manufacture  of  cheese,  casein  and  most  of  the  milk  fat 
are  precipitated  from  milk  by  rennet  at  a  suitable  temperature. 
The  curds  are  then  pressed,  to  squeeze  out  the  whey  and  reduce 
the  mass  to  a  proper  shape.  In  the  process  of  decay  the  fat 
increases  at  the  expense  of  the  casein,  and  numerous  alkaloidal 
substances,  extractives,  and  aromatic  acids  are  produced, 
which  give  a  decayed  cheese  its  aroma.  These  bodies  are  harm- 
less, put  rarely  a  poisonous  ptomaine  called  "  tyrotoxicon  "  is 
produced.  This  substance  has  also  been  discovered  in  cream, 
butter,  and  cheap  ice-creams,  and  in  milk  stored  during  hot 
weather.  The  symptoms  produced  by  tyrotoxicon  are  allied 
to  those  of  atropine  poisoning;  they  include  vertigo,  nausea, 
vomiting,  diarrhoea,  collapse,  muscular  cramps  and  rigors. 
Tyrotoxicon  is  diazo-benzene-butyrate,  and  its  effects  have  been 
chiefly  observed  in  America.  Various  kinds  of  parasites  grow 
in  decaying  cheeses,  but  they  do  not  seem  ordinarily  to  produce 
any  harmful  effects.  The  more  common  are:  Aspergillus  glaucus 
(causing  blue  or  green  mould),  Sporendonema  casei  (causing  red 
mould),  and  the  cheese  maggots  {Piophila  casei). 


wheat  flour  and  bread  379 

Wheat  Flour  and  Bread. 

Wheat  flour  contains  about  15  per  cent,  of  water,  8  to  12  per 
cent,  of  gluten  (vegetable  albumin),  and  about  70  per  cent,  of 
starch,  sugar,  and  dextrine.  It  is  very  deficient  in  salts  and 
fat.  In  the  finest  flour  nearly  all  the  outer  envelopes  of  the 
wheat  grain  are  separated.  This  separation  of  the  bran,  whilst 
it  renders  the  flour  fine  in  texture  and  white  in  colour,  deprives 
it  of  much  nutritious  matter,  for  bran  contains  15  per  cent, 
of  nitrogenous  substances,  35  per  cent,  of  fat,  and  57  per  cent, 
of  salts.  On  the  other  hand,  most  of  this  nutritious  matter  is  in 
a  form  difficult  of  digestion  and  irritating  to  the  bowels,  for  the 
outer  envelopes  of  the  wheat  grain  are  hard  and  silicious;  but 
bread  made  from  wholemeal  flour  is  favoured  by  many.  Where 
it  can  be  tolerated  its  use  may  be  advantageous,  as  it  promotes 
evacuation  of  the  bowels,  and  is  more  nutritious  than  ordinary 
white  bread.  It  is  certainly  deserving  of  trial  by  the  working 
classes,  whose  diet  is  often  deficient  in  fat  and  nitrogen;  and 
with  the  modem  methods  of  very  fine  grinding  its  irritant 
properties  are  reduced  to  a  minimum. 

The  wheat  grain  is  surrounded  by  a  tough,  branny  envelope, 
known  as  the  "  pericarp,"  which  forms  about  15  per  cent,  of  the 
grain;  within  the  pericarp  is  the  endosperm,  consisting  of  large, 
thin-walled  parenchymatous  cells  packed  with  starch  grains, 
forming  about  80  per  cent,  of  the  entire  grain.  At  the  broad 
end  of  the  grain  is  the  embryo  or  germ,  forming  about  i^  to  2 
per  cent,  of  the  grain. 

The  wheat  grain  is  converted  into  flour  by  milhng,  and  so  made 
suitable  for  bread-making.  The  entire  grain  may  be  ground  up  in 
milling,  and  used  as  such  for  making  bread,  being  then  known  as 
wholemeal.  A  portion  of  the  branny  husk  only  may  be  separated 
in  milling,  the  resulting  product  being  called  fine  meal  or  entire 
wheat  flour,  which  latter  is  evidently  a  misnomer.  Ordinary 
white  flour  is  obtained  by  the  removal  of  as  much  of  the  branny 
envelope  and  cellulose  portions  of  the  grain  as  possible,  leaving 
only  the  starch  grains  found  in  the  endosperm.  In  practice, 
however,  such  perfect  separation  is  not  attained,  and  the  very 
whitest  flour  always  contains  other  parts  of  the  grain  besides  the 
starch  grains  of  the  endosperm. 

The  products  other  than  white  flour  obtained  by  milling  are 
termed  in  the  trade  offal.     The  chief  of  these  are  bran,  pollard 


380  HYGIENE    AND    PUBLIC    HEALTH 

(bran  in  a  tiner  state  of  division),  germ,  fltiff  ox  fibre  (the  cellulose 
walls  of  the  parenchymatous  cells  of  the  endosperm),  and  sharps 
or  middlings  (mixtures  of  all  the  above). 

Stone-milling,  in  which  the  wheat  grains  are  ground  between 
two  millstones  arranged  horizontally,  the  lower  stationary  and 
the  upper  revolving,  has  now  been  largely  replaced  by  roller- 
milling,  the  wheat  being  crushed  between  revolving  fluted  iron 
rollers.  In  stone-milling  the  grain  is  crushed  into  wholemeal, 
and  the  separation  of  this  into  bran,  pollard,  middlings,  and  flour 
is  effected  by  sifting  through  cloths  with  meshes  of  different 
degrees  of  fineness.  In  roller-milling  the  grain  is  reduced  to 
flour  in  gradual  stages,  during  which  the  offal  is  continually 
removed  by  sifting  and  by  the  use  of  air  currents.  By  this 
method  a  more  complete  removal  of  bran  and  a  greater  yield  of 
highly  refined  flour  can  be  obtained  than  by  stone-milhng. 

The  products  of  the  mill  from  which  bread  is  made  are  classified 
as  follows:  (i)  Wholemeal,  produced  by  grinding  the  entire  wheat 
grain.  (2)  Fine  meal,  or  entire  n'heat  flour ,  a  portion  of  the  bran 
only  having  been  removed.  This  flour  can  be  prepared  both  by 
stone  and  roller  mills,  but  the  appearance  and  quality  vary 
according  to  the  variety  of  wheat  used  (red  or  white),  and  accord- 
ing to  the  amount  of  offal  removed.  It  contains  a  portion  of  the 
germ.  "  Standard  "  flour  is  of  this  class,  and  contains  80  per 
cent,  of  the  wheat  milled,  the  20  per  cent,  removed  consisting  of 
bran  and  cellulose.  It  contains  all,  or  nearly  all,  the  germ  and 
semolina.  (3)  Households  is  the  commercially  lower  grade  of 
flour  obtained  from  roller-mills.  It  contains  a  small  amount  of 
bran,  and  is  darker  than  (4)  Patent  grade  flour,  which  is  the 
flour  most  esteemed  by  bakers  for  bread-making,  as  it  contains 
the  least  amount  of  offal,  and  possesses  the  most  water-absorbing 
properties,  making  a  large  and  white  loaf  on  baking. 

As  regards  the  nutritive  values  of  these  various  products  of 
milling  in  the  form  of  flours  and  breads,  Dr.  J.  M.  Hamill,  in  his 
Report  to  the  Local  Government  Board,  states  that  the  differences 
which  exist  are  not  of  much  importance  to  the  average  adult, 
with  whom  bread  is  only  one  of  many  varied  constituents  of  his 
dietary.  The  differences  are  not  relatively  of  great  magnitude, 
and- they  may,  to  a  large  extent,  be  neutralized  by  imperfect 
absorption  from  the  digestive  tract.  There  are,  besides,  wider 
differences  in  the  protein  contents  and  energy  values  of  the 
various  flours  obtained  from  wheats  of  different  varieties  than 


WHEAT    FLOUR    AND    BREAD  38 1 

between  the  refined  white  flour  and  the  wholemeal  product  of 
a  given  wheat.  In  other  words,  a  refined  "  patent  "  flour  ob- 
tained from  one  variety  of  wheat  may  contain  considerably  more 
protein  and  available  energy  than  the  wholemeal  flour  of  another 
variety  of  wheat.  The  choice  of  a  particular  sort  of  bread  should 
depend  largely  on  the  idiosyncrasy  of  the  individual.  For  those 
with  good  teeth,  who  can  masticate  well,  and  to  whom  a  large 
undigested  residue  is  a  benefit  as  promoting  evacuation  of  the 
bowels,  a  wholemeal  loaf  is  to  be  recommended.  For  those,  on 
the  other  hand,  who  cannot  masticate  efficiently,  and  whose 
intestines  are  irritated  by  undigested  residues,  a  loaf  made  from 
the  white,  refined,  patent  grade  flour  will  be  most  suitable.  To 
some  the  "  nutty  "  flavour  of  the  "  standard  "  or  "  entire  wheat 
flour  "  loaf  is  an  advantage,  as  it  promotes  the  secretion  of  saliva. 
To  others  this  particular  flavour  may  be  disagreeable,  and,  there- 
fore, of  no  benefit. 

For  the  poor,  and  especially  for  the  children  of  the  poor,  into 
whose  dietary  bread  so  largely  enters,  the  question  is  a  little 
different,  and  the  cost  of  the  article  must  be  borne  in  mind.  As 
a  rule,  for  this  class  an  expenditure  on  a  larger  quantity  of  "  house- 
holds "  or  other  cheap  bread  will  be  better  than  purchasing  a 
smaller  quantity  of  a  high-priced  bread,  especially  if  the  cheap 
bread  contains  some  of  the  bran  and  germ  which  are  relatively 
rich  in  protein,  phosphorus-containing  organic  compounds,  and 
mineral  matters.  For  such  children,  wholemeal  bread  in  which 
the  bran  has  been  finely  ground,  or,  if  this  prove  too  irritating 
to  the  intestines,  "  standard  "  bread,  or  bread  made  from  "  entire 
wheat  flour,"  is  probably  the  best;  but  here  again  it  is  a  question 
of  relative  cost  as  compared  with  ordinary  "  household  "  bread. 
There  is  one  advantage  in  the  breads  containing  branny  particles 
—namely,  that  they  are  more  cleansing  for  the  gums  and  teeth, 
and  less  liable  to  leave  that  pultaceous  residue  on  the  margins  of 
the  gums,  which  a  very  white  bread  made  from  "  patent  grade 
flour  "  is  so  apt  to  do.  The  fermentation  of  this  residue  is  un- 
doubtedly a  strong  exciting  cause  of  caries  of  the  teeth,  especially 
in  children  whose  teeth  are  never  cleansed  with  a  tooth-brush. 

The  growing  practice  by  millers  of  bleaching  flour  has  also 
been  inquired  into  by  Drs.  Hamill  and  Monier-Williams  on 
behalf  of  the  Local  Government  Board.  The  bleaching  is 
undertaken  owing  to  the  demand  of  the  public,  and  therefore  of 
the  bakers,  for  very  white  bread.     Only  roller-milled  flour  is 


382  HYGIENE    AND    PUBLIC   HEALTH 

bleached.  The  bleaching  is  carried  on  in  electrical  machines 
in  which  air  is  made  to  pass  over  sparking  electrodes,  with  the 
resulting  formation  of  ozone  and  nitrogen  peroxide.  It  is  only 
the  latter  gas,  however,  that  has  any  bleaching  action  on  flour. 
There  appears  to  be  no  advantage  to  the  consumer  in  the  bleach- 
ing of  flour,  except  that  he  gets  a  whiter  loaf;  but  the  process 
is  advantageous  to  the  miller,  as  a  dark-coloured  flour  when 
whitened  bj'  bleaching  fetches  a  higher  price  than  it  otherwise 
would.  The  most  important  chemical  change  produced  by 
bleaching  is  the  formation  of  nitrites  from  the  nitrogen-peroxide, 
but  these  are  seldom  present  in  greater  amount  than  from  0-5  to 
I  or  2  parts  per  million.  With  the  higher  degrees  of  bleaching 
Monier- Williams  shows  that  there  is  some  increase  in  the  soluble 
proteins  and  carbohydrates  of  the  flour,  and  the  oil  becomes 
oxidized.     No  diazo-compounds  appear  to  be  formed. 

Phosphates  and  other  substances  (added  as  "  improvers  ") 
increase  the  water-absorbing  capacity  of  the  flour,  and  are  said 
to  improve  its  baking  qualities. 

Bread  is  made  by  mixing  water,  yeast,  and  a  little  salt  with 
wheat  flour  until  a  consistent  dough  is  formed,  which  is  allowed 
to  rise  before  a  hot  fire  and  then  placed  in  a  baking  oven.  By 
the  action  of  the  yeast  at  a  suitable  temperature,  some  of  the 
starch  is  changed  into  sugar,  and  the  sugar  splits  up  into  alcohol 
and  carbonic  acid  gas.  The  coherent  nature  of  the  gluten  pre- 
vents the  escape  of  the  carbonic  acid  gas,  which  forms  for  itself 
httle  cells  in  the  substance  of  the  loaf,  and  causes  the  spongy 
structure  characteristic  of  well-made  bread.  The  alcohol  escapes 
into  the  air.  It  is  important  not  to  let  the  fermentative  process 
go  too  far,  or  lactic  and  butyric  acids  may  be  formed,  which 
cause  the  bread  to  be  sour.  Alum  has  the  property  of  arresting 
this  change,  and  of  imparting  a  fine  white  colour  to  bread. 
Hence  its  frequent  use  in  baking  powders.  The  loaf  when 
"  risen  "  is  put  into  the  oven  and  baked.  It  appears,  from  ex- 
periments conducted  by  Drs.  Waldo  and  Walsh,  that  the  tem- 
perature of  the  interior  of  a  loaf  in  a  baker's  oven  is  not  sufficiently 
high  to  destroy  all  microbes.  The  process  of  baking,  therefore, 
does  not  sterilize  the  loaf. 

Aerated  bread  is  now  extensively  used.  In  this  system  COg 
gas  is  prepared  and  forced  through  the  dough  under  pressure. 
Its  great  advantage  lies  in  the  fact  that  there  is  no  fermentation 
as  in  ordinary  bread-making,  and  no  danger  of  sourness  and 


WHEAT   FLOUR   AND    BREAD 


383 


acidity  bein^  produced.  There  is  besides  no  loss  of  starch,  and 
no  yeast  is  left  in  the  bread  to  cause  fermentative  changes  in 
the  stomach,  giving  rise  to  acidity,  heartburn,  and  flatulence. 
On  the  other  hand,  the  yeast  fermentation  is  supposed  to  render 
the  bread  more  easily  attacked  by  the  digestive  juices — in  other 
words,  more  digestible.  Baking  powders  are  occasionally  used 
to  disengage  COg  gas,  and  cause  dough  to  rise.  They  usually 
consist  of    sodium  carbonate   and  some   acid  such   as  citric  or 


Fig.  67. — PucciNiA  Graminis  (x  about  200). 

tartaric,  mixed  with  rice-flour.  Baking  powders  are  also  sold 
in  which  the  acid  constituent  is  furnished  by  acid  phosphate, 
and  in  other  cases  by  the  sulphuric  acid  contained  in  some  form 
of  alum  salt.  The  calcium  acid  phosphate  commonly  employed 
often  contains  a  large  proportion  of  calcium  sulphate,  and  Hamill 
recommends  that  this  impurity  should  not  be  allowed  to  exceed 
10  per  cent. 

Under    the    microscope    wheat     flour    is    seen     to     consist 


o  c  o  o    o  o  o 


'oe» 


°  O 


O    O 


Fig.  68. — Smut  Spores:  Uredo  segetuj 
(x  about  200). 


Fig.  69. — AcARUS  farin^e 
(x  about  40). 


of  round  or  oval  starch  grains,  of  very  various  sizes.  The 
smallest  are  mere  points,  whilst  the  larger  ones  may  reach  to 
ToVo  inch  in  diameter  or  more.  Intermediate  sizes  are  very 
often  absent.  The  hilum  and  concentric  lines  of  the  starch 
grains  are  barely  visible,  if  at  all.  Portions  of  the  outer  envelopes 
of  the  wheat  grain  may  be  detected  in  the  coarser  and  more 
branny  flours. 


384 


HYGIENE  AND  PUBLIC  HEALTH 


Wheat  grains  are  subject  to  attack  by  certain  parasites,  viz. 
(figs.  67  to  71),  "  smut  "  {Uredo  segehmi)  and  "  bunt  "  {Uredo 
foetida),  the  latter  being  the  commonest;  "  rust  "  or  Pticcinia 
graminis,  which  attacks  the  stem  and  leaf;  and  ergot  {O'ldium 
ahortifaciens)  (fig.  y^),  which,  however,  is  more  often  a  disease  of 


Fig.  70. — ViBRiONEs  tritici 
(x  about  40). 


Fig.  71. — Weevil 
( X  about  40). 


rye.  Amongst  the  numerous  animal  destroyers  of  wheat  are: 
Vibrio  tritici,  or  ear  cockle,  which  destroys  the  grain  and  fills  it 
with  a  cotton-like  substance;  A carus  farina  ;  and  the  weevil,  or 
Calandra  granaria  (fig.  71),  a  little  insect — visible  to  the  naked 
eye — which  eats  the  core  out  of  the  grain,  leaving  only  the  shell. 


Fig.  72.  —  Section  of 
Wheat  Grain:  Outer 
Coat. 

«, Girdle  cells ;  b,  cerealin 
cells  (x  about  50). 


Fig.  yi- — A,  Ear  of  Rye  with  Ergot 
— THE  Latter  shown  as  germinat. 

ING      AND     PRODUCING     "  ClAVICEPS 

purpurea";  B,  a  Slice  of  Ergot 
(x  about  250). 


Lolium  temulentum,  or  darnel  seeds,  occasionally  find  their  way  into 
flour,  and  have  given  rise  to  symptoms  of  narcotic  poisoning  among 
some  of  those  who  consumed  the  bread  made  from  such  flour. 

Other  fungi   may  likewise   be   recognized  by  means  of  the 
microscope  in  the  flour  made  from  bHghted  and  diseased  corn ; 


WHEAT   FLOUR   AND   BREAD 


385 


and  flour  and  bread,  when  badly  stored  and  allowed  to  become 
damp,  become  the  seat  of  growth  of  moulds  and  fungi  such  as 
Mucor  mucedo,  Penicillium,  and  Aspergillus  (see  pp.  366,  368). 
AH  these  growths  are  apt  to  produce  dyspepsia  and  diarrhoea, 
whilst  the  prolonged  consumption  of  ergoted  bread  may  give 
rise  to  the  symptoms  of  ergotism,  viz.,  painful  cramps  in  the 
limbs  and  gangrene  of  the  extremities.  Ergot  may  also  be 
detected  by  the  herring-like  smell  of  propylamine  which  is  pro- 
duced when  liquor  potassae  is  added  to  ergoted  flour. 

With  wheat  at  its  present  low  price,  adulteration  is  very 
little  practised.  Alumina  is  normally  present  to  a  very  sUght 
extent  in  flour  and  bread  (equivalent  to  6  to  10  grains  of  alum 
in  a  4  pound  loaf).  When  alum  is  added  in  any  quantity,  its 
presence  may  be  detected  by  pouring  a  fresh  infusion  of  logwood, 
made  with  distilled  water,  over  the  flour  or  bread.  The  colour 
of  the  logwood  changes  to  a  lavender  or  violet-grey  in  the  presence 
of  alum.  There  can  be  little  doubt  that  alumed  bread  tends 
to  produce  dyspepsia  and  constipation,  and  it  permits  of  an 
inferior  flour  being  sold  as  a  good  one,  but  it  is  now  only  added 
in  small  quantities  in  certain  baking  powders. 

The  adulteration  of  wheat  flour  with  other  grains,  such  as 
barley,  potato,  beans,  peas,  maize,  oats,  rye,  and  rice,  is  now 
but  little  resorted  to. 

The  nitrogenous  substances  in  these  grains  have  httle  or  no 
adhesive  properties  hke  wheat  gluten,  so  that  bread  of  an  inferior 
quality  can  only  be  made  from  them. 

The  nutritive  values  of  some  of  these  cereals  will  be  seen  from 
the  following  table: 


Whe.it 

(winter- 

Barley. 

Oats. 

Maize. 

Rye. 

Rice. 

sown). 

Starchi  . 

6371 

63-51 

4978 

64-66 

61-87 

77-66 

Nitrogenous  matter 

{i.e.,  albumin,  ce- 

realin,   etc.) 

IS'S3 

11-46 

14-67 

14-27 

14-87 

9-34 

Cellulose 

3"03 

7-28 

13-53 

1-86 

3-23 

traces 

Sugar^  . 

2-57 

1-34 

2-36 

1-94 

4-30 

0-38 

Fat         .          .          . 

1-48 

1-03 

5-14 

3-58 

1-43 

0-19 

Mineral  matter 

i-6o 

2-32 

2-66 

1-35 

1-85 

0-28 

Moisture 

I2-08 

13-06 

11-86 

12-34 

12-45 

12-15 

Total      . 

loo-oo 

100-00 

loo-oo 

loo-oo 

lOC'OO 

lOOOO 

1  The  starch  includes  from  i  to  1-5  per  cent,  of  dextrine,  and,  together 
with  cellulose  and  sugar,  comprises  the  carbo-hydrates  of  the  cereals. 
^  The  saccharine  body  is  allied  to  cane  sugar  in  its  reactions. 

25 


386  HYGIENE   AND   PUBLIC   HEALTH 

It  will  be  seen  that  barley  is — compared  with  wheat — poor  in 
nitrogenous  matter  and  sugar,  but  rich  in  cellulose  and  mineral 
matter;  that  oats  are  exceptionally  rich  in  cellulose  and  fat, 
possess  a  high  amount  of  mineral  matter,  but  are  relatively 
poor  in  starch;  that  maize  possesses  a  high  amount  of  fat,  but 
the  cellulose  is  low;  that  rye  is  exceptionally  rich  in  sugar,  and  in 
other  respects  closely  approximates  to  wheat;  and  that  rice  is 
rich  in  starch,  but  poor  in  everything  else. 

Barleymeal,  oatmeal,  peas,  lentils,  and  maize  or  Indian  corn,, 
are  all  most  nutritious  and  fattening,  and  very  cheap.  They 
are  easily  made  into  most  nourishing  porridges,  soups,  or  pud- 
dings, with  a  little  milk,  and  form  very  valuable — though  greatly 
neglected — foods  for  people  of  small  incomes.  Starchy  foods 
must  be  carefully  cooked  to  render  them  digestible.  By  boiling 
or  otherwise  cooking,  the  cellulose  coats  of  the  starch  granule 
are  ruptured,  and  the  saliva  and  pancreatic  juice  then  have 
ready  access  to  the  granulose — the  inner  contents  of  the  granule. 

Barley. — -The  starch  grains  are  almost  indistinguishable  from 
wheat.  Barley  is  very  nutritious,  and  the  ash  is  rich  in  iron 
and  phosphates. 

Rye. — The  starch  grains  are  like  those  of  wheat,  but  many 
have  a  peculiar  rayed  hilum.  Rye  can  be  made  into  bread, 
which  is  very  acid  and  dark  coloured,  and  liable  to  produce 
diarrhoea  in  those  unaccustomed  to  it. 

Oatmeal. — The  starch  grains  are  small  and  angular,  and  tend 
to  cohere  into  rounded  masses.  It  is  most  nutritious  and  some- 
what laxative.  When  badly  prepared,  oatmeal  may  contain 
hairs  and  husks,  which  are  liable  to  form  intestinal  con- 
cretions. 

Maize. — The  starch  grains  are  small,  compressed,  and  faceted. 
Pellagra,  or  Elephantiasis  Italica,  is  a  constitutional  disease 
operating  destructively  on  the  integument.  It  is  most  prev- 
alent among  those  living  under  the  adverse  conditions  of  dirt 
and  poverty  so  rife  in  Italy.  That  the  consumption  of  diseased 
or  damaged  maize,  to  the  exclusion  of  other  diet,  is  probably  the 
main  factor  in  producing  epidemics  of  the  disease  is  supported  by 
the  circumstance  that  in  the  Lombardo- Venetian  territory,  where 
this  is  the  chief  food  of  the  agricultural  labourer,  the  disease  is 
most  in  evidence,  and  also  by  the  fact  that  pellagra-like  symptoms 
have  been  produced  by  feeding  lower  animals  with  diseased 
maize.     But  there  are  some  grounds  in  support  of  the  theory 


PLATE   1 


ARROWROOT 


CO 


:r^: 

■         ^ 

>--.'■ 

-f 

\' 

t.<j*,e«'  J' 

''"~^ 

■C  ~ 

>€^ 

5„:: 

/ 

PEA  BEAN 

STARCH     GRANULES.      IX    250.) 


E    C.  lioiisficld.  fholo. 


To  face  pai^c  386 


PLATi:   1 


^Wy^^€r^'' 


^j^  y^  s-r 


q7  \,^r^  '^- 


.O 


C&'^D  ^s     -  o 


Wr^^^ 


MAIZE  TAPIOCA 

STARCH     GRANULES,      (x   250.) 

/•:.  C  Housliclil.  tliolo. 


To  fail'  f'agt-  3S6. 


WHEAT   FLOUR    AND    BREAD  387 

that  the  disease  is  an  infective  disorder  transmitted  by  a  small 
biting  insect. 

Peas  and  Beans.  —Pea  starch  grains  are  more  or  less  oval, 
and  many  of  them  have  a  central  longitudinal  cleft  extending 
nearly  the  whole  length  of  the  grain.  Bean  starch  cells  are 
somewhat  larger  and  more  flattened,  and  the  longitudinal  cleft 
is  crossed  by  transverse  fissures.  Peas  and  beans  contain  a 
large  amount  of  proteid  substance  called  legumin  (hence  the 
name  of  Leguminosae  applied  to  this  natural  order  of  plant), 
also  sulphur  and  phosphorus.  They  are  highly  nutritious,  but 
somewhat  indigestible,  and  are  apt  to  give  rise  to  flatus  from 
the  formation  of  sulphuretted  hydrogen. 

Rice. — The  starch  grains  are  very  minute,  angular,  and 
faceted;  in  shape  like  maize  starch  cells,  but  very  much  smaller. 
Rice  is  poor  in  everything  but  starch,  which  is,  however,  ex- 
tremely digestible  when  cooked.  It  has  been  held  to  give  rise  to 
Beri-beri,  when  polished  rice  has  been  too  exclusively  used  for 
human  food. 

Arrowroot. — There  are  many  different  kinds  of  arrowroot, 
obtained  from  various  countries.  As  a  rule,  the  starch  grains 
are  oval  or  pyriform  in  shape,  of  large  size,  and  with  the  hilum 
as  a  slight  cleft  or  cross  at  the  larger  end  of  the  grain.  The 
concentric  lines  are  very  well  marked. 

Sago  and  Tapioca. — The  starch  grains  of  sago  are  large, 
irregular  in  shape,  with  ill- defined  concentric  lines.  Those  of 
tapioca  resemble  sago,  but  are  considerably  smaller. 

Potato. — The  starch  grains  of  potato  are  very  characteristic. 
Many  of  them  are  large  and  pyriform  in  shape,  the  hilum  being 
at  the  smaller  end,  and  the  concentric  lines  are  very  well  marked. 
Potatoes  are  very  deficient  in  proteids  and  fats,  but  the  starch 
is  most  digestible  when  properly  cooked;  and  they  are  valuable 
antiscorbutics,  for  they  contain  large  quantities  of  the  salts  of 
the  vegetable  acids — malates,  tartrates,  and  citrates.  The  juice 
of  the  potato  is  acid.  Potatoes  are  better  cooked  by  steaming  in 
their  skins  than  by  boiling  when  peeled;  for  by  the  first  method 
there  is  no  loss  of  the  salts  to  the  water  used  for  boiling,  as  occurs 
in  the  second  method. 

In  the  case  of  all  vegetables,  and,  in  fact,  in  all  cooking  pro- 
cesses, soft  water  is  far  better  than  hard  water. 

The  consumption  of  potatoes  has  been  responsible  for  the 
occurrence  of  symptoms  of  solanin  poisoning. 


388 


HYGIENE  AND  PUBLIC  HEALTH 


BEVERAGES. 


Fig.  74. — Coffee  :  Cells  of  Testa  and 
Cellular  Structure  (x  about  200). 


Coffee. 

Coffee  berries  contain  fat,  legumin,  sugar,  dextrine,  vegetable 
acids,  and  mineral  salts;  also  an  aromatic  oil,  an  alkaloid — 
caffein  (about   0-8   per  cent.) — and  an  astringent — caffeo-tannic 

acid.  When  the  berry  is 
roasted,  it  swells  from  the 
formation  of  gases,  the 
sugar  is  changed  into 
caramel,  and  the  aroma  is 
developed.  The  roasted 
coffee  is  made  into  a 
beverage  by  infusion  with 
nearly  boiling  water.  If 
the  water  is  used  at  a 
boiling  temperature  some 
of  the  aroma  is  lost. 
The  coffee  infusion  acts  as  a  stimulus  to  the  nervous  system; 
it  increases  the  frequency  of  the  heart's  action,  the  urinary  ex- 
cretion, and  the  action  of  the  skin,  and  is  said  to  increase  the 
carbonic  acid  given  off  from  the  lungs.  It  has  considerable 
effect  in  removing  the  sensation  of  fatigue.  It  is  valuable  as  a 
beverage  for  men  undergoing  exertion  both  in  hot  and  cold 
climates,  from  its  stimulant 
and  invigorating  qualities. 
The  heat  of  the  infusion  is 
useful  in  cold  climates,  whilst 
the  increased  action  of  the  skin 
produces  a  coohng  effect  in 
hot  climates. 

The  principal  adulterant  of 
coffee  is  chicory.  Under  the 
microscope,  diligent  search  should  be  made  for  the  long  oval 
cells  of  the  testa  of  the  berry,  with  their  irregular  cross-markings 
(fig.  74) ;  and  fragments  of  the  internal  structure  of  the  berry 
may  be  seen,  consisting  of  an  irregular  network  of  fibres  forming 
a  cellular  structure,  in  which  are  contained  dark  angular  masses 
and  oil  globules.  All  these  structures  are  better  seen  before  the 
berry  is  roasted  and  ground.     Chicory  is  revealed  by  the  presence 


Fig.  75. — -Chicory:  Dotted  Ducts 
AND  Cellular  Structure  ( x  about 
200). 


BEVERAGES 


389 


of  fragments  of  much  coarser  areolar  tissue,  and  by  the  long  dotted 
ducts,  which  arc  quite  characteristic  (fig.  75). 

Roasted  coffee  floats  for  a  considerable  time  in  water,  owing 
to  the  gases  that  are  developed  in  roasting,  and  to  the  quantity 
of  fat  it  contains;  whilst  roasted  chicory  rapidly  sinks.  Unlike 
coffee,  chicory  contains  no  aromatic  oil  nor  caffcin,  but  it  has 
much  sugar  in  its  composition.  When  mixed  with  coffee  it  serves 
to  sweeten  it,  and  causes  a  darker  coloured  infusion  than  pure 
coffee;  but  the  stimulating  effect  of  the  mixture  is  less  than  thnt 
of  pure  coffee.  Rare  adulterants  of  coffee  are  other  starches 
(such  as  potato  and  sago),  and  caramel  or  burnt  sugar. 

Tea. 

Dried  tea  leaves  contain  albumin,  extractives,  dextrine,  and 
mineral  salts,  also  tannin  (about  13  per  cent.),  an  aromatic 
oil,  and  an  alkaloid — thein  (3  per  cent.).  Green  tea  contains 
more  tannic  acid  and  ethereal  oils  than  black  tea,  and  is  pre- 
pared from  younger  leaves,  but  the  thein  appears  to  be  generally 
less  in  amount.  The  difference  between  black  and  green  teas 
is  entirely  due  to  their  mode  of  prepara- 
tion; they  are  both  derived  from  the  same 
plant.  Formerly  tea  was  exported  almost 
exclusively  from  China,  but  now  Indian  and 
Ceylon  teas  have  come  largely  into  the 
market. 

Tea  should  be  made  with  boiling  water, 
but  it  should  not  be  allowed  to  stand  for 
more  than  five  minutes,  the  infusion  being 
then  poured  into  another  vessel.  If  this  is 
not  done,  so  much  tannin  is  extracted  as 
to  cause  the  infusion  to  be  bitter  and 
astringent,  and  most  unwholesome.  If  soft 
water  is  used,  a  smaller  quantity  of  tea  is 
necessary  than  with  hard  water,  as  the  soft 
water  extracts  more  from  the  leaves  than 
hard.  Dextrine,  glucose,  tannin,  thein,  the  volatile  oil,  and  a 
small  quantity  of  the  albumin  pass  into  the  infusion.  Tea 
should  not  be  taken  with  or  shortly  after  meals,  as  the  tannin 
tends  to  coagulate  the  albumins  of  the  food  undergoing  the 
process  of  digestion. 

The  action  of  tea  on  the  system  is  similar  to  that  of  coffee.     It 


Fig.  76. — ^Tea  Leaf. 


390  HYGIENE    AND    PUBLIC   HEALTH 

is,  therefore,  valuable  as  a  nervous  stimulant  and  restorative  in 
fatigued  conditions  of  the  body.  The  abuse  of  tea  leads  to 
weakened  digestion,  constipation  from  the  astringent  properties 
of  the  tannin,  and  nervous  depression  leading  to  insomnia  and 
trembling — the  effects  of  the  volatile  oil  and  thein. 

The  structure  of  the  tea  leaf  is  characteristic,  and  is  best  seen 
when  the  leaf  is  young  and  green.  It  is  oval  in  shape  (fig.  76), 
with  a  serrated  border,  each  serration  being  spine  mounted,  and 
the  serrations  terminating  a  little  before  the  point  of  attachment 
of  the  stalk;  the  primary  veins  run  out  alternately  from  the 
midrib,  and  turn  towards  the  point  of  the  leaf,  but  without 
reaching  the  border,  the  venation  being  looped;  the  apex  of  the 
leaf  is  notched.  Adulteration  with  foreign  leaves  is  now  little 
practised;  but  used  leaves  may  be  dried,  mixed  with  gum  and 
rolled,  and  sold  as  sound  tea.  Green  tea  used  to  be  coloured  or 
faced  with  indigo,  Prussian  blue,  and  other  mineral  substances. 

Cocoa. 

Cocoa  is  a  food  as  well  as  a  beverage,  and  is  much  less  astringent 
than  tea  or  coffee.  Cocoa  nibs  contain  nearly  50  per  cent,  of  oil 
(cocoa  butter),  proteids  about  15  per  cent.,  and  theobromin — 
allied  to  thein  and  caffein^o-5  to  17  per  cent.  The  ash  is 
rich  in  phosphate  of  potash.  For  people  of  weak  digestion,  some 
of  the  fat  of  the  cocoa  should  be  removed  by  heat  and  pressure. 

Cocoa  is  generally  adulterated  with  sugar  and  the  cheaper 
starches,  in  order  to  disguise  the  large  amount  of  fat  and  to 
render  it  more  palatable.  The  starch  grains  of  cocoa  are  very 
small,  and  are  often  seen  massed  in  the  intercellular  spaces  of 
the  structure  of  the  nib. 

Mineral  Waters. 
These  are  either  derived  from  natural  springs,  the  water  of 
which  contains  gases  (usually  COg)  or  mineral  salts  in  solution 
(salts  of  potassium,  sodium,  magnesium  or  lithium),  or  they  are 
manufactured  by  impregnating  ordinary  river,  spring,  or  well 
water  with  COg  gas,  and  dissolving  in  it  small  quantities  of  the 
mineral  salts  usually  found  in  natural  waters.  Both  kinds  of 
water  have  come  very  largely  into  use  in  recent  years.  Besides 
the  stimulant  effect  upon  the  digestive  organs  of  the  contained 
CO2  and  the  dietetic  or  aperient  value  of  the  mineral  salts,  these 
waters  serve  a  useful  purpose  in  providing  a  pure  beverage  for 
consumption  in  cases  where  there  may  be  hesitation  to  drink  the 


BEVERAGES  3gi 

ordinary  water  provided  for  domestic  purposes,  on  the  ground 
of  its  impurity.  Care  shquld  be  taken,  however,  to  choose  a 
mineral  water  which  does  not  contain  an  excess  of  common  salt, 
producing  thirst,  or  an  excess  of  alkaline  salts,  which  act  as 
dejjressants  on  the  nervous  system.  Travellers  both  at  home 
and  abroad  usually  show  a  wise  discretion  in  their  preference 
for  mineral  waters  to  the  ordinary  water  of  the  establishments 
in  which  they  are  staying  or  seeking  refreshment.  Too  much 
reliance,  however,  should  not  be  placed  on  the  purity  of  all 
artificial  waters,  as  in  more  than  one  instance  it  has  come  to 
our  knowledge  that  certain  manufacturers  have  obtained  their 
waters  from  grossly  polluted  sources. 

There  is  one  other  danger  in  the  use  of  the  artificially  aerated 
waters  that  requires  mention.  They  often  exhibit  traces,  and 
sometimes  very  decided  traces,  of  lead.  This  metal  is  dissolved 
from  lead  pipes  or  leaden  apparatus  used  in  the  manufacture  of 
the  COg,  and  the  water  charged  with  this  gas  holds  the  lead  in 
solution.  Another  possible  source  of  the  metal  is  the  silicate  of 
lead  which  enters  into  the  composition  of  the  glass  bottles  in 
which  such  waters  are  stored.  The  habitual  use  of  these  waters 
containing  traces  of  lead  might  in  time  lead  to  the  development 
of  symptoms  of  lead  poisoning,  the  source  of  which  would  in  all 
probability  be  overlooked. 

Fermented  Liquors. 
A  solution  of  grape  sugar  when  subjected  to  the  action  of  the 
yeast  plant  {Saccharomyces  cerevisice)  at  a  temperature  of  from 
20°  C.  to  30°  C,  is  mainly  split  up  into  alcohol  and  carbonic  acid. 

C6H,20,=  2C2H,p  +  2CO.,. 

The  yeast  plant  is  composed  of  minute  organized  cells,  oval 

in  shape,  and  with  granular  protoplasm  (fig.  77).     In  the  presence 

of  saccharine  fluids  at  a  suitable  tempera-  p,  ^    0 

ture,   the  cells  undergo  enormous  multi-  £0^^^  e»5,®  "^  <=^f°°°o 

plication  by  the  process  of  budding,  and  ^  ~^®i''^^o-'^o'^«'°°^ 

the  alcoholic  fermentation  ensues.     Under  ^<?  ®5&,§  R,  ^^0  o  ^ 

the  microscope,  the  cells  which  are  bud-  li?  '^  oj^s 

ding  may  be  seen  as  one  large  cell  united  pj^  -^ Torula  cere- 

to  one  or  two  smaller  cells,  end  to  end;       visi.^i  :  Yeast  Pl.\nt 

(x  about  200). 
or   groups   of   several   buddmg   cells   are 

attached  together.     The  CO2  escapes  as  gas  from  the  fermenting 

liquor,  whilst  the  alcohol  remains  dissolved  in  the  solution. 


392  HYGIENE    AND    PUBLIC   HEALTH 

The  fermented  drinks  may  be  considered  under  the  heads  of 
spirits,  wines,  and  beers. 

Spirits. — Brandy  is  spirit  derived  from  the  grape.  It  contains 
about  50  per  cent,  of  alcohol,  the  remainder  of  the  liquor  being 
water,  in  which  are  held  various  secondary  products,  including 
acids,  aldehydes,  ethers,  furfural  and  higher  alcohols.  Its  specific 
gravity  is  generally  from  0-930  to  0-940  at  62°  F.  Rum  is  dis- 
tilled from  fermented  molasses. 

Whisky  is  made  by  distillation  of  malted  grain.  When  new, 
it  contains  amylic  alcohol  or  fusel  oil,  a  substance  which,  when 
present  in  any  quantity,  produces  rapid  intoxication,  followed  by 
intense  headache  and  depression.  The  percentage  of  alcohol 
in  whisky  is  much  the  same  as  in  brandy.  Gin  is  weaker  in 
alcohol;  it  contains  oil  of  juniper,  and  is  sweetened  with  various 
aromatic  substances.  Absinthe  is  a  liqueur  flavoured  with 
various  essential  oils,  and  contains  oil  of  wormwood,  a  powerful 
poison  to  the  nervous  system. 

Brandy,  as  sold  commerciall3^  is  now  very  largely  blended 
with  varying  amounts  of  spirit  obtained  from  the  distillation 
of  corn  grain  spirit,  etc.  The  dietetic  and  medicinal  values  of 
these  sophisticated  articles  are  probably  inferior  to  those  of  the 
genuine  wine  spirit;  and  recent  legal  decisions  show  that  the 
sale  of  blended  spirits,  when  brandy  is  demanded,  is  an  infringe- 
ment of  the  Sale  of  Food  and  Drugs  Acts.  Analysis  differen- 
tiates between  a  pot  still  and  a  patent  still  spirit,  because  the 
secondary  products  are  practically  absent  in  the  latter  owing  to 
the  spirit  being  more  highly  rectified  by  means  of  the  patent  or 
fractionating  still.  A  therapeutic  value  has  been  ascribed  to 
these  secondary  products,  but  the  evidence  is  not  conclusive. 

The  secondary  products  in  whisky  are  small  in  amount ;  it  con- 
tains relatively  more  higher  alcohols  but  less  compound  ethers 
than  brandy;  it  further  contains  traces  of  empyreumatic  or  tarry 
substances  derived  from  the  malting  process. 

Wines. — What  are  known  as  the  lighter  wines — the  Bordeaux, 
Burgundies,  Rhine  wines,  Champagnes,  and  Moselles- — contain 
usually  less  than  10  to  15  per  cent,  of  alcohol  by  volume.  The 
stronger  wines — port,  sherry,  and  madeira — contain  from  15  to 
25  per  cent,  of  spirit.  Besides  alcohol,  wines  contain  various 
aromatic  compound  ethers  which  impart  the  bouquet,  albuminous 
and  colouring  matters,  sugar,  free  organic  acids,  and  the  acid 
salts  of  the  vegetable  acid  series,  including  tannic  acid  (which 


BEVERAGES  393 

is  largest  in  amount  in  new  port  wines)  and  mineral  salts,  chiefly 
-hose  of  potassium. 

Wines  are  manufactured  from  the  fermented  juice  of  the  grape. 
Cheap  wines  are  largely  made  from  other  fruits,  and  even  grape 
juice  wine  is  subject  to  various  fortifications  and  adulterations  to 
fit  it  for  different  markets.  Home-made  wines  and  cider  are 
occasionally  manufactured  or  stored  in  earthenware  vessels, 
coated  inside  with  a  litharge  glaze,  which  readily  gives  up  large 
quantities  of  lead  to  such  acid  Hquids,  and  may  be  thus  produc- 
tive of  lead  poisoning.  If  earthenware  vessels  are  used,  they 
should  be  coated  with  a  hard  salt  glaze.  When  wine  is  kept 
long  in  cask  or  bottle,  there  is  a  deposit  of  the  colouring  matter 
and  tannic  acid,  and  some  of  the  sugar  disappears.  If  air  is  not 
absolutel}'  excluded,  the  acetous  fermentation  is  liable  to  be  set 
up  from  the  entrance  of  the  ferment  {Mycoderma  acdi),  which 
transforms  alcohol  into  acetic  acid  (CoHgO  becomes  C2H4O2), 
and  the  wine  is  soured.  The  more  common  adulterants  used  are 
sugar,  various  ethers,  logwood  and  other  colouring  agents,  alum, 
and  sulphate  of  lime.  The  latter  improves  the  colour  of  cheap 
wines,  and  the  addition  is  known  as  the  "  plastering  "  of  wine. 
The  practice  is  injurious,  and  by  giving  rise  to  the  formation  of 
potassium  sulphate  it  induces  a  purgative  effect  upon  consumers. 

Beers. — These  beverages  were  formerly  made  from  malt  and 
hops  only;  now  they  can  be  legally  made  from  starch  and  sugar 
and  various  vegetable  bitters. 

Pure  beer  is  the  fermented  Hquor  obtained  from  the  germinating 
grain  of  barley.  The  grains  are  made  to  partially  germinate  by 
being  first  moistened  and  then  kept  warm  until  they  begin  to 
sprout.  A  small  quantity  of  the  ferment  "  diastase  "  is  thus 
produced.  Further  germination  is  then  prevented  by  heating 
the  barley  in  kilns  and  thus  converting  it  into  "  malt."  The 
malt  is  next  subjected  to  "  mashing  "  by  mixing  with  water  at 
180°  F.  and  well  crushing  and  stirring  for  about  two  hours. 
During  this  process  the  diastase  acts  upon  the  starch  and  largely 
converts  it  into  the  sugar^ — ■"  maltose,"  which  is  easily  ferment- 
able. After  clarifying,  the  infusion  is  boiled  with  hops,  and  then 
the  cooled  liquor  or  "  wort  "  is  transferred  to  vats  to  ferment 
(yeast  being  added).  When  this  alcoholic  fermentation  has  pro- 
ceeded far  enough  the  yeast  is  removed  and  the  beer  is  run  into 
casks. 

In  recent  years  glucoses  and  invert  sugars  have  been  largely 


394  HYGIENE    AND    PUBLIC   HEALTH 

substituted  for  the  malt,  and  these  sugars  have  been  obtained 
from  rice  and  other  starches  which  are  not  fermentable  until  they 
are  converted  into  "  invert  sugar  "  by  the  action  of  dilute 
sulphuric  acid.  The  commercial  sulphuric  acid  is  Uable  to  con- 
tain a  considerable  amount  of  arsenic  (derived  from  the  iron 
pyrites  used  in  its  manufacture) ;  and  this  circumstance  was 
responsible  for  a  considerable  outbreak  of  arsenical  poisoning 
among  beer  consumers,  chiefly  in  the  north-western  part  of 
England,  in  the  winter  of  1900-1901.  Amounts  of  arsenic 
varying  from  -^  to  i  grain  per  gallon  of  beer  were  found  by 
analysis,  and  some  invert  sugars  were  found  to  contain  arsenic 
equivalent  to  2  04  grains  of  arsenious  oxide  per  pound. 

It  may  be  stated  that  traces  of  arsenic  have  been  found  in 
jams,  sweets,  lemonade,  liqueurs,  sugar,  and  treacle — all  now 
largely  manufactured  from  glucose — and  also  in  several  chemical 
substances — such  as  sulphate  of  soda,  phosphate  of  soda,  car- 
bonate of  soda  and  potash,  caustic  soda,  sulphurous  acid,  sul- 
phites, borax,  oxide  of  iron  (used  for  colouring  confectionery), 
etc.  It  has  also  been  pointed  out  that  the  coke  used  for  kilning 
the  barley  gives  off  traces  of  arsenic  when  burned. 

The  percentage  of  alcohol  in  beer  varies  from  3  per  cent,  in  the 
lighter  to  6  or  7  per  cent,  in  the  heavy  beers.  There  are  also 
contained  in  beer,  malt  extract,  4  to  15  per  cent.,  free  organic 
acids,  traces  of  albuminous  matters,  and  salts. 

Considered  as  articles  of  diet,  wine  and  beer  will  produce 
effects  which  may  be  partly  ascribed  to  the  action  of  alcohol  on 
the  system,  and  partly  to  the  other  constituents  of  which  they 
are  composed. 

Leaving  out  of  consideration  for  the  moment  the  effects  of  the 
alcohol,  it  will  be  seen  that  wine  and  beer  possess  some  of  the 
properties  of  a  food.  They  contain  sugar  and  starchy  matters, 
mineral  salts  rich  in  potash  and  phosphates,  and  a  considerable 
amount  of  the  vegetable  acids  and  their  salts  which  are  so  valu- 
able as  antiscorbutics.  The  compound  aromatic  ethers  in  wine 
may  also  act  as  aids  to  indigestion,  by  promoting  the  flow  of  the 
pancreatic  and  intestinal  juices;  and  the  bitters  of  beer  act  as 
stomachic  tonics  and  appetizers.  Little  can  be  said  against  the 
use  of  beer  and  wine  in  strict  moderation;  but  taken  habitually 
in  excess,  they  lead  to  the  storage  up  of  superfluous  fat  in  the 
tissues,  and  they  interfere  with  the  proper  elimination  of  effete 
matters;  imperfect  oxidation  leads  to  an  excessive  formation  of 


BEVERAGES  395 

uric  acid,  and  a  plethoric  and  gouty  habit  is  produced,  eventu- 
ally tending  to  palpable  disease.  These  effects  are,  doubtless,  in 
part  due  to  the  excess  of  alcohol  taken  into  the  system,  but  not 
entirely.  Lessened  metamorphosis  has  a  considerable  share  in 
their  production. 

Effects  of  Alcoh)!. 

Alcohol  when  taken  into  the  body  is  rapidly  absorbed  un- 
changed into  the  blood.  Taken  in  excess,  it  speedil}^  commences 
to  pass  out  of  the  body  in  an  unaltered  condition.  The  principal 
channel  of  elimination  is  the  lungs  and  breath,  but  small  portions 
are  got  rid  of  by  the  skin,  the  urine,  and  the  bowels.  The  greater 
portion,  however,  of  the  alcohol  (98  per  cent.)  is  destroyed  in  the 
body.  In  fact,  when  taken  in  small  (not  excessive)  quantities, 
alcohol  acts  as  a  food,  supplying  heat  and  energy  by  its  oxidation 
in  a  similar  manner  to  the  fats  and  carbo-hydrates. 

After  full  doses  of  alcohol  given  to  a  healthy  man  or  animal, 
the  following  effects  have  been  noted:  i.  The  vessels  of  the 
stomach  are  dilated,  and  the  flow  of  gastric  juice  augmented. 

2.  The  force  and  frequency  of  action  of  the  heart  are  increased. 

3.  There  is  partial  paralysis  of  the  vaso-motor  nerves  to  the 
superficial  vessels,  which  dilate,  causing  flushing  of  the  skin  of  the 
face  and  other  parts.  4.  The  brain  is  partially  anaesthetized; 
the  rapidity  of  external  impressions,  the  power  of  concentrated 
thought,  and  the  discrimination  of  the  senses,  are  all  lessened,  as 
is  also  sustained  voluntary  muscular  power.  5.  The  temperature 
of  the  body  is  slightly  depressed;  but  although  there  may  be  a 
decreased  elimination  of  CO2  by  the  lungs,  there  is  no  delay  or 
diminution  in  the  metamorphosis  of  tissue,  for  the  excretion  of 
urea  in  the  urine  is  not  affected.  6.  The  acidity  and  water  of 
the  urine  are  somewhat  increased. 

The  long  continued  immoderate  use  of  alcohol  leads  to  degenera- 
tive changes,  primarily  in  the  stomach  and  liver,  and  at  a  later 
period  in  the  kidnej^s,  lungs,  brain  and  bloodvessels.  The  de- 
generation is  characterized  by  increased  growth  of  interstitial 
fibrous  tissue,  which  in  course  of  time  shrinks  and  causes  atrophy 
of  gland  cells  and  loss  of  function.  Chronic  catarrh  and  cirrhosis 
of  the  stomach  with  cirrhosis  of  the  liver,  followed  by  dropsy 
and  haemorrhage/  are  the'^well-recognized  results  of  alcoholic 
intemperance 

The  effect  of  such  intemperance  in  shortening  life  is  now  uni- 
versally recognized.     Statistics  bear  overwhelming  evidence  on 


396  HYGIENE    AND    PUBLIC   HEALTH 

this  point.  It  may  be  stated  generally  that  the  mortality  of  the 
intemperate  is  from  four  to  five  times  greater  than  that  of  the 
strictly  temperate  of  the  same  age  and  in  the  same  class  of  life. 
When  the  mortahty  of  all  occupied  males  in  1890-2,  at  ages 
ranging  from  twenty-five  to  sixty-five  years,  from  alcoholism 
and  diseases  of  the  liver,  is  expressed  as  100,  and  the  mortality 
in  each  separate  industry  is  expressed  as  a  figure  proportional  to 
that  standard,  the  following  results  are  obtained  by  Dr.  Tatham 
(Supplement  to  the  55th  Report  of  the  Registrar-General): — 
Deaths  from  Alcohol  and   Diseases  of  the  Liver   (i8c,c-2). 


All  occupied  males 

.        TOO 

Dock  Labourer 

•      195 

Coachman,  cabman 

•      153 

Chimney  sweeper    . 

.     200 

Costermonger 

.     163 

Butcher 

.     228 

Coal  heaver    . 

.     16S 

Brewer 

.     250 

Fishmonger    . 

.     168 

Inn  servant    . 

.     420 

Musician 

.     168 

Inn  keeper     . 

•     7ii 

Hairdresser    . 

.     175 

Dr.  Tatham  points  out  that  the  mortality  from  alcoholism  is 
often  registered  as  due  to  other  causes  that  are  known  to  be  fre- 
quently associated  with  alcohoHc  excess,  and  this  is  often  pur- 
posely done  out  of  regard  to  the  feelings  of  relatives.  Experience 
proves  that  the  liver  is  the  organ  which,  more  than  any  other,  is 
affected  prejudicially  by  intemperance. 

Those  engaged  in  the  brewing  and  licensed  victualling  trades 
are  notably  an  intemperate  class;  but,  naturally,  if  the  temperate 
men  in  these  trades  could  be  excluded,  the  figures  indicating 
special  disease  of  organs  would  be  very  much  magnified. 

All  evidence  points  to  the  fact  that  alcohol,  except  in  strict 
moderation,  is  injurious  to  men  who  are  exposed  to  extremes  of 
climate  (great  heat  and  great  cold),  or  who  have  to  undergo  great 
bodily  or  mental  labour.  Its  effect  on  the  circulation  is  distinctly' 
injurious  to  those  engaged  in  hard  bodily  work,  for  it  causes  the 
heart  to  do  more  work  without  conferring  any  counterbalancing 
advantage. 

In  strictly  moderate  doses  alcohol  has  not  been  proved  to  do 
any  harm ;  and,  taken  in  the  form  of  beer  or  wine,  many  of  the 
inhabitants  of  our  large  towns  find  it  a  useful  aid  to  digestion 
and  assimilation.  But  it  must  be  remembered  that  there  are 
idiosyncrasies  as  regards  alcohol,  and  that  what  is  harmless  to 
one  individual  may  be  injurious  to  another.  For  thoroughly 
healthy  people,  alcohol  in  any  form  presents  no  advantages,  and 
for  children  and  young  people  it  is  decidedly  injurious.   The  com- 


BEVERAGES  397 

parative  immunity  enjoyed  by  drunken  persons  from  the  usual 
effects  of  accidents  is  due  to  the  paralysis  of  those  nervous  centres 
through  which  a  sliockwould  be  produced  in  a  condition  of  sobriety. 
The  Report  of  the  Departmental  Committee,  which  was 
appointed  to  report  upon  Physical  Deterioration,  brought  out 
the  following  facts: — 

1.  Tliat  the  abuse  of  alcoholic  stimulants,  whether  in  the  lorm  of  spirits, 
wine,  or  beer,  is  largely  responsible  for  physical  deterioration,  and  that  it 
leads  to  disease  in  most  tissues  and  organs  of  the  body. 

2.  That  alcoholic  excess  reduces  the  natural  power  of  resistance  to 
disease  possessed  by  healthy  individuals,  rendering  them  especially  liable 
to  many  inflammatory  disorders,  causing  them  to  suffer  much  more 
severely  from  any  illness  they  may  contract,  and  making  their  recovery  slow. 

3.  That  intemperance  predisposes  to  consumption. 

4.  That  children  of  intemperate  parents  are  seriously  affected ;  they 
frequently  suffer  from  paralysis,  epilepsy,  and  idiocy,  which  lead,  if  not  to 
death,  to  their  permanent  disablement.  From  statistics  obtained,  it  wai: 
found  that  the  mortality  among  children  of  intemperate  parents  was  many 
times  greater  than  among  children  of  sober  parents  of  the  same  class. 

5.  That  the  increase  in  lunacy  is  largely  due  to  intemperance,  and  that 
there  is  also  an  increase  in  the  number  of  cases  of  general  paralysis  from  the 
same  cause. 

The  Swedish  (Gothenburg)  system  seeks  to  diminish  the  abuse 
of  alcoholic  stimulants,  to  acquire  public-houses,  and  to  devote 
the  profits  accruing  from  the  sale  of  alcoholic  drinks  to  public 
purposes.  There  is  strict  local  option  as  to  the  provision  of 
public-houses,  and  conditions  are  imposed  upon  the  sale  of  wines 
and  spirits,  but  not  of  beer. 

CONDIMENTS. 

Vinegar  is  prepared  by  acetous  fermentation  from  white  wine 
or  malt.  Vinegars  made  chiefly  from  unmalted  barley,  maize, 
rice  and  other  grains,  and  from  sugar  or  molasses,  are  some- 
times sold  as  malt  vinegar.  Its  acidity  should  amount  to  from 
about  3  to  5  per  cent,  of  glacial  acetic  acid.  It  is  largely  adul- 
terated with  sulphuric  acid,  which  is  injurious  from  its  tendency 
to  form  insoluble  sulphate  of  lime  in  the  body.  Acetic  acid  is 
neutralized  in  the  system,  and  ultimately  becomes  transformed 
into  an  alkaline  carbonate. 

In  cases  where  vinegar  has  been  added  to  "  tinned  articles," 
such  as  pickles,  fish,  etc.,  the  liquid  should  be  tested,  where 
necessary,  for  lead,  zinc,  copper,  or  tin,  since  the  vinegar  adds 
materially  to  the  solvent  action  of  the  juices,  etc.,  upon  the 
vessels  containing  them. 


398  HYGIENE    AND    PUBLIC   HEALTH 

Lemon  and  lime  juice  contain  vegetable  acids,  chiefly  citric, 
about  30  grains  in  a  fluid  ounce.  They  are  frequently  mixed 
with  water,  and  sometimes  with  other  acids,  such  as  sulphuric 
and  tartaric  acids.  Lime  juice  has  generally  a  little  less  acid 
than  lemon  juice.     They  are  most  valuable  antiscorbutics. 

These  vegetable  acids  and  their  salts  are  also  largely  contained 
in  all  kinds  of  fresh  fruit;  but  perhaps  the  chief  advantage  of 
fruit  in  a  diet — when  taken  early  in  the  day  (before  breakfast) — 
is  its  tendency  to  promote  evacuation  of  the  bowels. 

Mustard  is  generally  adu'.terated  with  wheat  flour  and  turmeric, 
for  the  pure  seed  possesses  too  acrid  a  taste  to  be  palatable; 
pepper  with  rice  and  minerals.  Added  mineral  matter  in  pepper 
can  be  mostly  separated  by  shaking  up  thoroughly  with  chloro- 
form— when  foreign  mineral  matters  settle. 

Pickles  are  now  generally  coloured  with  chlorophyll  and 
vegetable  colouring  matters.  Formerly  copper  was  much  used 
for  this  purpose. 

Sweetmeats  and  confectionery  are  now  almost  invariably  sold 
free  from  any  injurious  colouring  matter  The  coloration  is 
imparted  by  careful  heating  of  the  sugar,  by  which  a  variety  of 
shades  of  yellow  and  brown  may  be  obtained,  or  by  the  use 
of  such  harmless  organic  matters  as  saffron,  turmeric,  annatto 
(yellow),  cochineal  (red),  logwood  (violet),  and  chlorophyll  (green). 
The  use  of  the  mineral  and  metallic  salts  for  colouring  purposes 
— those  containing  iron,  lead,  copper,  arsenic,  chromium,  and 
zinc — is  now  hardly  practised  at  all. 

An  easy  and  rapid  test  for  the  separation  of  poisonous  from 
harmless  colouring  matters  may  be  applied  as  follows:  Dissolve 
some  of  the  sweetmeat  in  distilled  water.  If  the  colouring  matter 
is  soluble  and  is  bleached  on  adding  solution  of  sodium  hypo- 
chlorite, it  is  organic  and  probably  harmless.  If  the  colouring 
matter  is  insoluble,  or  is  soluble  and  is  not  bleached  by  sodium 
hypochlorite,  it  is  probably  mineral  and  possibly  poisonous. 

The  anihne  dyes  are  but  little  used  for  colouring  sweetmeats. 
They  are  soluble  in  alcohol  and  mostly  innocuous,  if  quite  free 
from  arsenic,  which  is  usually  the  case.  Picric  acid  (trinitro 
phenol),  a  yellow  dye,  is  injurious;  and  the  same  may  be  said 
of  the  yellow  colouring  matter  derived  from  gamboge,  and  a 
few  aniline  dyes,  viz.: — Naphthol  green,  aniline  yellow,  Martius' 
yellow,  Bismarck  brown,  methylene  blue,  and  gentian  violet. 


CANNED    AND    BOTTLED   FOODS 


399 


Canned  and  Bottled  Foods. 

The  amount  of  tinned  or  canned  food-stuffs  upon  the  market 
is  very  considerable,  and  it  constitutes  an  increasing  part  of 
the  food  supply  of  large  communities.  The  canning  of  food 
has  the  effect  of  preserving  a  large  amount  of  material  which 
would  not  otherwise  be  available  for  food,  and  it  is  thus  a  pro- 
vision which  cheapens  the  cost  of  living;  moreover  for  the  pur- 
poses of  our  Colonies,  of  the  Army  and  Navy,  or  for  expeditions 
to  parts  of  the  world  where  food  is  scarce,  canned  food  is  essential. 
There  is  no  doubt  that  when  meat  preserved  in  this  way  has 
to  be  consumed  for  long  periods,  the  consumer  suffers  less  than 
when  salted  meat  is  exclusively  eaten;  but  experience  has 
shown  that  health  cannot  be  maintained  for  several  months  on 
these  canned  foods  unless  a  certain  amount  of  fresh  animal  or 
vegetable  food  is  introduced  into  the  diet. 

It  is,  of  course,  of  prime  importance  that  the  material  to  be 
canned  should  be  in  a  wholesome  condition  at  the  time  of  canning, 
but  it  is  also  very  important  that  the  cans  in  which  the  material 
is  placed  should  be  of  good  quality  and  sound.  The  coating  of 
the  can  with  tin  should  be  properly  done,  so  that  no  flaws  are 
perceptible  with  the  magnifying  glass,  as  otherwise  the  iron 
beneath  will  rust  through;  the  tin  used  for  coating  should  not 
contain  more  than  i  per  cent,  of  lead;  and  "  terne-plate,"  which 
consists  of  2  parts  of  tin  to  one  of  lead,  should  be  prohibited; 
the  solder  employed  in  the  tins  should  not  contain  more  than  lo 
per  cent,  of  lead,  and  should  be  kept  entirely  on  the  outside  of 
the  tin;  and  those  tins  which  are  to  contain  much  acid  juice 
(namely,  vinegar,  plum,  and  asparagus  juice)  should  be  lacquered 
inside.  It  is  very  desirable  that  the  date  of  the  canning  should 
be  required  to  be  stamped  on  each  can. 

The  usual  process  of  canning  is  briefly  as  follows: — The 
food  is  placed  in  the  tin  and  the  lid  is  soldered  on.  The  small 
"  blow-hole,"  which  is  generally  in  the  centre  of  the  lid,  is  next 
sealed  by  solder.  The  sealed  tin  is  then  placed  in  either  a  steam 
retort  at  115°  C.  for  from  one  to  two  hours,  or  in  a  boihng  solution 
of  calcium  chloride  for  the  same  period,  or  in  ordinary  boiling 
water  for  about  four  hours.  The  tin  is  then  removed  from  the 
retort  or  boiling  solution,  and  the  solder  seal  is  quickly  melted  off, 
by  means  of  a  red-hot  instrument,  when  the  expanded  gases 
escape;   the  small  blow- hole  is  again  sealed  with  solder,   and 


400  HYGIENE   AND   PUBLIC   HEALTH 

the  tin  and  its  contents  are  again  placed  in  the  steam  retort  for 
another  hour.  The  finished  tin  has  then  two  concave  surfaces 
and  emits  a  hard  sound  on  percussion. 

Should,  however,  there  be  any  flaw  in  the  "tins,"  or  the  solder 
seal  be  imperfectly  applied,  or  should  the  heating  process  be 
ineffectually  performed,  then  the  contents  may  go  bad.  In 
this  event,  owing  to  the  accumulation  of  the  gases  of  putrefaction, 
the  tops  and  bottoms  of  the  "  tins  "  become  quite  flat,  and  later 
on  convex  outwards,  and  the  tin  when  struck  gives  out  a  hollow 
or  drum-like  sound.  It  is  not  difficult,  therefore,  in  the  majority 
of  cases,  to  detect,  before  opening  them,  those  "  tins  "  in  which 
the  contents  are  bad.  Sometimes,  however,  "  blown  tins  " 
have  been  punctured  to  allow  the  accumulated  gases  to  escape, 
and  the  small  opening  has  been  subsequently  closed  by  solder. 
The  presence  of  two  solder  points  on  a  tin  might  therefore  justify 
a  suspicion  that  this  practice  had  been  resorted  to,  but  as  a 
rule  the  solder  upon  the  original  blow-hole  would  be  melted  and 
resoldered. 

The  two  solder  points  do  not  necessarily  indicate  fraud,  because 
it  is  sometimes  found  more  expeditious  and  convenient  to  make 
a  second  blow-hole  to  let  out  the  expanded  gases  rather  than 
to  unseal  the  original  one.  Again,  what  appears  to  be  a  second 
solder  point  may  sometimes  be  nothing  more  than  a  splash  of 
solder  accidentally  deposited. 

Beveridge  has  shown  that  the  "  blowing  "  of  tins  is  due  to  the 
spores  of  Bacillus  sporogenes  of  Klein,  which  are  extremely  re- 
sistant to  heat.  This  organism  is  present  in  the  colon,  and 
contaminates  all  meat.  It  may  not  be  destroyed  by  the  so- 
called  sterilization;  may  remain  inert  for  long  periods  if  the  tins 
are  stored  at  a  low  temperature;  but  may  develop  if  the  tem- 
perature reaches  37°  C.  or  thereabouts.  It  is  non-pathogenic  to 
animals,  but  decomposes  the  meat,  and  renders  it  unfit  for 
human  consumption. 

These  facts  explain  the  circumstance  that  tins  of  meat  which 
have  passed  the  makers'  tests,  and  have  kept  good  for  months, 
suddenly  become  blown  and  unfit  for  use.  It  was  recognized 
that  this  occurrence  was  not  due  to  injury  of  the  tin  through 
rust  and  entrance  of  air  organisms;  for  if  so,  the  gas  produced 
by  putrefaction  would  have  escaped,  and  no  blowing  would  have 
resulted. 

The  recommendation  is  accordingly  made  that  the  tempera- 


CANNED    AND    BOTTLED   FOODS  4OI 

ture  of  sterilization  should  be  raised  to  120°  C.  (240°  F.),  and 
that  this  temperature  should  be  maintained  for  one  hour. 

The  bulging  of  tins  results  from: — (i)  The  formation  of  gas 
by  putrefaction  of  the  contents  of  the  tin;  (2)  the  displacement 
of  the  contents  from  rough  handling  and  rough  usage  so  as  to 
make  the  ends  bulge;  (3)  the  freezing  of  the  contents  of  tins 
of  liquid  or  semi-liquid  foods,  as  when  kept  in  cold  storage,  this 
sometimes  making  the  ends  bulge  for  the  same  reason  that  frost 
bursts  water-pipes.  It  may  be  stated  that  the  bulging  of  tins 
of  condensed  milk  is  not  necessarily  due  to  any  of  the  above 
causes;  it  may  be  produced  by  gas  formed  by  electrolytic  action 
between  the  metal  of  which  the  cans  are  composed  and  the  acids 
generated  by  the  growth  of  bacteria  in  the  milk  before  the  latter 
was  condensed.  The  vinegar  in  which  certain  vegetables  are 
conserved  may  produce  gases  in  the  same  way. 

The  dangers  to  health  in  the  consumption  of  tinned  or  canned 
foods  arise  (i)  from  changes  in  the  food  itself  (which  may  either 
be  of  a  definite  putrefactive  nature  or  due  to  the  development 
of  non-putrefactive  ptomaines  or  toxins) ;  (2)  from  the  use 
of  antiseptics;  (3)  from  the  addition  of  colouring  agents;  or 
(4)  from  impurities  yielded  by  the  tins.  Putrefactive  changes 
cause  the  generation  of  gas  within  the  tin,  which  leads  to  a 
blowing  or  bulging,  and  when  the  bulged  end  is  tapped  the 
sound  is  muffled  or  drum-hke.  The  most  dehcate  means  of 
detecting  "  blowing  "  is  to  place  a  drop  of  water  on  the  top  of  the 
tin  and  .then  puncture  the  tin  through  the  water.  The  water  is 
sucked  inwards  as  a  rule  in  a  tin  with  sound  contents ;  but  a  few 
fine  bubbles  escape  through  the  water  if  the  tin  is  slightly  blown. 
On  opening  the  tin  a  discoloration  of  the  inside  of  the  tin  is  often 
observable;  the  contents  are  often  discoloured  and  soft  (fish,  for 
instance,  is  often  yellowish,  soft  and  friable) ;  and,  lastly,  the 
odour  of  putrefaction  may  be  perceptible. 

Viry  states  that  putrefactive  changes  in  canned  foods  may 
take  place  without  the  formation  of  any  gas;  and  it  is  certain 
that  the  evil  consequences  which  have  sometimes  been  traced  to 
the  consumption  of  canned  food  were  due  to  ptomaines  which 
were  formed  in  partly  decomposed  material  prior  to  canning. 

The  development  of  ptomaines  and  toxins  in  food,  and  the 
use  of  colouring  agents  and  antiseptics,  are  dealt  with  elsewhere. 
But  a  word  must  be  said  with  reference  to  the  impurities  yielded 
by  the  tins.      Metallic  tin  may  be  dissolved  by  acids  or  by  oil 

26 


402  HYGIENE   AND   PUBLIC   HEALTH 

(as  in  the  case  of  canned  pieces  of  pine,  lobster,  condensed  milk, 
and  sardines) ;  and  this  metal  is  the  most  frequent  metallic 
impurity  found  in  the  juices  of  preserved  food,  especially  of  fruit. 
Lead  may  be  dissolved  from  the  solder,  or  from  the  varnishes 
and  enamels  which  have  sometimes  been  used  in  connection 
with  the  tins.  It  is  most  important,  therefore,  that  any  solder 
used  should  be  beyond  the  possibility  of  contact  with  the  tinned 
material.  In  the  punched  out  or  moulded  can,  which  represents 
a  great  improvement  in  manufacture,  there  is  only  one  joint — 
namely,  that  between  the  lid  and  the  body,  and  this  is  soldered  in 
such  a  way  as  to  prevent  the  possibiUty  of  the  solder  appearing  on 
the  inside  of  the  can.  It  is,  moreover,  possible  by  taking  a  moulded 
jointless  body  to  firmly  clamp  the  folded  edges  of  the  lid  and 
body  in  a  special  machine,  so  that  no  solder  whatever  is  employed. 
In  some  tins  a  solder  trap  is  used,  this  being  a  small  cup-shaped 
piece  of  tin  attached  immediately  under  the  vent  hole.  Glass 
containers,  sealed  by  air-tight  metal  caps  with  rubber  washers, 
are  also  used;  the  heat  emplo5'ed  in  the  sterilization  of  the  con- 
tents being  generally  lower  than  in  the  case  of  canned  food  in 
order  to  avoid  breakages.  \^ery  rarely  have  traces  of  arsenic, 
copper  and  zinc  been  obtained  from  the  juices  of  preserved  foods. 
In  cases  where  the  tin  is  attacked  by  the  contained  juices,  etc.,  a 
slaty- blue  discoloration  is  often  to  be  seen. 

The  presence  of  chemical  preservatives  in  canned  or  bottled 
food  suggests  that  by  their  addition  it  has  been  sought  to  over- 
come undesirable  conditions  in  the  meat  itself,  prior  to  canning; 
but  a  very  small  amount  of  borax  may  be  present  in  potted 
material  containing  ham  or  bacon  from  the  circumstance  that 
these  articles  are  packed  between  thin  layers  of  borax  before  they 
are  sent  over  to  this  country,  and  that  while  the  borax  penetrates 
but  little  into  the  fat,  it  reaches  considerable  distances  into  the 
other  tissues. 

In  conclusion  some  advice  may  be  offered  with  reference  to 
the  examination  and  selection  of  tinned  articles.  It  is  desirable 
to  avoid  cheap  brands,  and  more  especially  those  which  do  not 
bear  the  name  of  the  maker.  A  very  good  idea  of  the  nature 
of  the  contents  can  generally  be  obtained  from  an  examination 
of  the  tins.  Poor  quality  tins  commonly  contain  poor  quality 
material.  Of  all  tinned  articles  of  food  preserved  fruits  are  the 
most  hkely  to  contain  metallic  impurities;  it  is  well,  therefore, 
only  to  purchase  these  when  they  are  bottled.      Any  canned 


TOBACCO  403 

meat  or  fish,  which  is  not  of  good  colour  and  firm  resistance, 
should  be  avoided;  and  any  indication  of  marked  loss  of  colour, 
of  softness,  and  of  friability,  is  highly  suggestive  of  unwholesome 
material.  Furthermore,  it  is  very  desirable  that  the  contents 
of  the  can  should  be  eaten  during  the  day  on  which  it  was  opened, 
for  there  have  been  recorded  instances  where  those  who  have 
eaten  the  material  fresh  from  the  can  have  escaped,  whilst  others, 
partaking  of  the  same  material  the  next  day,  have  suffered  from 
poisoning. 

Tobacco. 

The  effects  produced  by  the  excessive  smoking  of  tobacco 
have  often  been  discussed.  Of  all  the  components  of  tobacco 
smoke,  nicotine  is  by  far  the  most  important;  the  other  com- 
ponents, including  pyridine,  are  of  little  moment.  Smoking 
raises  the  blood- pressure  by  vaso-constriction,  accelerates  the 
heart  and  respiration,  and  increases  intestinal  movements. 
Functional  disorders  of  digestion  and  gastric  catarrh,  irritation 
of  the  pharynx,  defective  vision,  nervous  tremors,  and  dilatg.tion 
of  the  heart,  are  all  ascribed  to  excessive  tobacco-smoking ; 
and  it  is  maintained  by  some  that  serious  circulatory  disorders, 
including  arterio-sclerosis,  may  be  produced.  It  is,  of  course, 
towards  the  end  of  a  pipe,  cigarette,  or  cigar,  that  most  of  the 
nicotine  is  taken  into  the  system. 


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CHAPTER  IX 

THE  CONTAGIA— COMMUNICABLE  DISEASES  AND 
THEIR  PREVENTION— HOSPITALS 

The  Contagia. 

Certain  diseases  of  men  and  animals  have  long  been  known  to 
be  communicable  from  one  individual  to  another,  and  recent 
investigations  have  shown  that  some  of  these  diseases  are  not 
only  communicable  from  one  individual  of  the  same  species  to 
another,  but  are  interchangeable  between  animals  and  men,  and 
between  men  and  animals.  Various  doctrines  have  been  held 
at  different  times  as  to  the  nature  of  the  contagia  in  these  diseases, 
but  the  theory  of  their  constitution  which  is  embraced  in  what 
is  known  as  the  "  germ  theory  of  disease  "  need  only  be  discussed 
here. 

The  germ  theory  assumes  that  the  contagia  are  microscopic 
living  particles,  organized  in  structure  and  for  the  most  part 
capable  of  independent  life  both  within  and  without  the  animal 
body.  These  organic  particles  are  believed  to  form  part  of 
that  large  class  the  schizomycetes,  which  embraces  the  lowest  and 
least  developed  forms  of  vegetable  life,  and  constitutes  a  link, 
as  it  were,  between  the  two  great  divisions  of  the  animal  and 
vegetable  world.  To  this  class  belong  the  bacilli,  micrococci, 
spirilla,  vibriones,  etc.,  which  exist  in  such  enormous  numbers  in 
every  region  and  climate. 

The  view  that  the  particles  of  contagia  are  really  minute 
organisms  is  favoured  by  the  analogy  of  the  processes  of  typical 
infectious  disease  in  the  human  body  to  those  of  fermentation  in 
an  organic  liquid.  When  the  yeast  plant  obtains  access  to  a 
saccharine  fluid  and  the  temperature  is  suitable,  the  cells  of  the 
yeast  rapidly  multiply,  and  after  a  certain  time,  which  corre- 
sponds with  the  period  of  incubation  in  an  infectious  disease, 

408 


THE    CONTAGIA  409 

changes  are  produced  in  the  saccharine  hquid,  evidenced  by  the 
formation  of  alcohol  and  carbonic  acid,  which  eventually  render 
it  incapable  of  being  further  acted  upon  by  that  particular 
ferment.  So  in  infectious  disease,  there  is  a  period  of  incubation 
which  may  be  supposed  to  arise  from  the  delay  necessary  to 
allow  of  the  contagious  particles  overcoming  the  influences 
exerted  against  them  by  the  antagonistic  cells  and  fluids  of  the 
body,  thus  enabling  the  growth  and  multiplication  of  the  con- 
tagious particles  to  take  place;  during  the  course  of  the  fever 
specific  bactericidal  substances  are  produced  in  the  blood,  which 
either  are  directly  poisonous  to  the  specific  microbes,  or  else 
enable  the  leucocytes  to  ingest  and  destroy  them;  and  specific 
antitoxins  are  also  generated,  which  counteract  the  bacterial 
toxins.  As  a  result  of  these  defensive  actions  on  the  part  of  the 
organism  invaded  by  the  disease,  the  fever  runs  its  course, 
recovery  ensues,  and  the  body  is  rendered  unassailable  by  a 
similar  infection  for  months  or  years,  or  in  some  cases  until  the 
end  of  life. 

It  is  evident  that  the  contagion,  once  introduced  into  the 
animal  body,  generally  grows  and  multiplies  enormously;  but 
the  organisms  of  diphtheria  and  tetanus  multiply  locally  only  to 
a  hmited  extent,  producing  the  symptoms  by  the  soluble  toxins 
which  they  elaborate.  The  least  atom  of  infectious  material 
serves  to  inoculate  small-pox  in  a  susceptible  person,  but  the 
contagious  matter  produced  in  the  course  of  the  disease  would 
be  sufficient  to  inoculate  many  thousands.  In  each  special 
disease  the  contagion  multiplies  chiefly  in  those  tissues — the 
mucous  and  epithehal — which  are  more  especially  affected  by 
it,  and  the  infection  is  cast  oft'  from  the  body  in  large  part  with 
the  secretions  of  these  tissues.  Freed  from  the  body,  the  infec- 
tion maybe  conveyed  directly  from  the  diseased  to  the  healthy, 
or  it  may  lie  dormant  in  the  clothes  or  furniture  of  the  sick  room 
for  a  certain  period,  and  still  retain  its  contagious  properties. 

This  property,  possessed  by  some  of  the  contagia,  of  retaining 
unimpaired  their  powers  of  infection  for  long  periods  after 
leaving  the  body,  is  further  evidence  in  favour  of  their  bacterial 
nature.  It  is  known  that  many  bacteria  are  propagated  by 
sporulation,  and  that  the  spores,  the  immature  forms  of  the  adult 
species,  can  resist  extremes  of  temperature  and  drying  which  are 
destructive  to  the  fully  developed  organism.  That  liquids, 
gases,  or  any  non-living  material  could  retain  infective  properties 


410  HYGIENE    AND    PUBLIC    HEALTH 

for  long  periods  after  expulsion  from  the  body,  when  subjected 

to  the  physical  and  chemical  forces  opposed  to  their  stabihty,  is 

highly  improbable. 

In  some  diseases,  the  contagion  does  not  appear  to  be  capable 

of  maintaining  an  independent  existence  outside  the  animal  body, 
except  possibly  for  short  periods.  In  these  cases  the  infection 
is  conveyed  by  direct  contact  or  inoculation. 

The  microbic  origin  of  many  communicable  diseases  may  be 
considered  to  be  established  beyond  doubt,  and  this  fact  is  strong 
presumptive  evidence  in  favour  of  the  remainder — in  which  no 
such  connection  has  as  yet  been  positively  traced — being  causally 
dependent  upon  specific  micro-organisms.  Koch  has  laid  down 
certain  conditions,  upon  the  proof  of  which  alone  can  it  be 
definitely  stated  that  a  particular  micro-organism  is  the  cause 
of  a  certain  disease.     They  are  as  follows: — 

1.  The  micro-organism  must  be  found  in  the  blood,  lymph,  or 
diseased  tissues  of  man  or  animal,  suffering  from  or  dead  of  the 
disease. 

2.  This  micro-organism  must  be  isolated  from  the  blood, 
lymph,  or  tissues,  and  cultivated  in  suitable  media  outside  the 
animal  body.  These  pure  cultivations  must  be  carried  on 
through  successive  generations  of  the  organism. 

3.  A  pure  cultivation  thus  obtained  must,  when  introduced 
into  the  body  of  a  healthy  susceptible  animal,  produce  the 
disease  in  question. 

4.  In  the  inoculated  animal  the  same  micro-organism  must 
again  be  found. 

It  is  evident  that,  postulate  No.  3  being  inapplicable  to  human 
beings,  the  complete  sequence  of  proof  cannot  be  arrived  at  in 
the  case  of  exclusively  human  diseases.  But  in  the  case  of  the 
diseases  affecting  both  men  and  the  lower  animals,  inasmuch  as 
the  animals  can  be  submitted  to  processes  of  inoculation,  the 
entire  chain  of  proof  can  be  substantiated. 

It  is  not  desirable  to  retain  the  term  "  contagious,"  as  distinct 
from  "  infectious,"  in  regard  to  the  communicable  diseases, 
unless  the  term  "  contagious  "  is  limited  to  those  diseases  which 
are  only  transferable  by  direct  inoculation,  such  as  syphilis. 
The  term  "  zymotic  "  is  usually  applied  to  those  communicable 
or  infectious  diseases  which  occur  in  epidemics;  but  nowadays 
it  is  customary  to  restrict  the  term  "  zymolysis  "  to  the  action 
of  the  chemical  or  unorganized  ferments  known   as  enzymes. 


THE   CONTAGIA  4IT 

Therefore,  zymotic,  as  a  term,  does  not  necessarily  imply  that 
the  disease  is  dependent  upon  a  living  organized  body  or  germ. 

A  distinction  may  be  made  between  "  infection  "  and  "  in- 
toxication ";  by  the  former  is  implied  an  invasion  of  the  body 
by  a  living  germ,  and  by  the  latter  the  poisoning  of  the  body  by 
chemical  agents,  usually  the  products  of  the  activity  of  a  living 
germ.  Anthrax  affords  a  typical  example  of  infection,  in  which 
the  bacillus  invades  the  whole  body;  and  tetanus  affords  an 
example  of  "  intoxication,"  for  in  this  disease  the  bacillus  is 
localized  to  the  seat  of  injury,  and  the  toxic  products  are  absorbed 
from  this  spot  into  the  general  system. 

The  use  of  the  word  "  specific  "  as  applied  to  these  diseases 
presupposes  a  specific  origin  for  each — an  origin,  that  is  to  say, 
from  a  pre-existing  case  of  the  disease  by  means  of  a  specific 
virus  or  organized  living  germ.  The  specific  origin  of  most  of  the 
communicable  diseases  can  hardly  be  doubted.  The  eruptive 
fevers  are  specific  and  they  breed  true;  i.e.,  a  case  of  measles,  for 
instance,  cannot  give  rise  to  mumps  or  whooping-cough,  but  only 
to  measles,  and  the  infection  cannot  arise  de  novo,  but  must  be 
sought  for  in  a  pre-existing  case.  But  the  true  specificity  of 
some  zymotic  diseases  is  not  yet  thoroughly  established,  such  as 
hospital  fevers,  summer  diarrhoea  or  zymotic  enteritis,  and  perhaps 
dysentery. 

Hospital  fevers,  however,  are  certainly  due  to  micro-organisms 
either  in  the  air  of  the  wards,  or  on  the  patient's  skin  or  wound. 
Dysentery,  too,  is  probably  always  due  to  an  organism  such  as 
the  Amoeba  coli,  or  a  bacillus,  of  which  several  have  recently 
been  isolated  and  are  said  to  produce  dysentery  (Kruse,  Flexner, 
etc.). 

Diarrhoea  may  be  induced  by  chills;  but  in  all  probability  a 
chill  only  lowers  the  resisting  power  of  the  lymphoid  tissue  in 
the  intestinal  walls,  thus  enabhng  the  micro-organisms  present 
to  multiply  abnormally. 

The  eruptive  fevers  are  remarkable,  chiefly  for  occurring  in 
epidemics,  often  at  regularly  recurring  periods.  The  contagion 
being  very  commonly  disseminated  through  the  air,  it  is  easy  to 
understand  how  these  diseases,  once  introduced  into  a  com- 
munity, spread  with  considerable  rapidity,  until  the  diminution 
of  susceptible  persons  or  some  other  undetermined  factor  causes 
the  epidemic  to  languish  and  finally  die  out. 

There   are   other  diseases  which   at   times  take  on  epidemic 


412  HYGIENE   AND   PUBLIC  HEALTH 

extension,  but  are  mostly  endemic;  that  is  to  say,  they  are 
always  present  in  certain  localities  where  conditions  of  excre- 
mental  pollution  of  water,  air,  food,  or  soil  favour  the  passage 
of  the  specific  virus  from  one  individual  to  another;  and  this 
constant  occurrence  of  isolated  or  sporadic  cases  gives  rise  to 
the  sudden  and  widespread  dissemination  termed  an  epidemic  at 
certain  seasons,  when  external  conditions  are  favourable.  The 
introduction  of  public  water  supplies  into  towns  has,  no  doubt, 
tended  to  cause  certain  epidemics  of  enteric  fever  and  cholera  to 
reach  further  and  spread  wider  than  formerly;  for  if  a  public 
water  supply  is  specifically  polluted  at  its  source,  the  contagion  is 
carried  to  a  far  larger  number  of  households  than  could  possibly 
be  the  case  where  each  house  has  its  own  well  or  spring. 

When  an  epidemic  assumes  very  extensive  (geographical)  pro- 
portions, it  is  termed  a  pandemic.  For  instance,  cholera  has 
often  been  widely  distributed  in  both  Asia  and  Europe  at  one 
and  the  same  time,  and  plague  exhibits  the  same  pandemic 
tendencies. 

The  subject  of  bodily  susceptibility  to  the  action  of  the  various 
contagia  requires  a  passing  notice.  It  is  evident  that  in  early 
childhood  the  bodily  susceptibility  to  various  contagia  is  verj^ 
great,  and  this  susceptibility  diminishes  with  advancing  age. 
The  protective  influence  in  the  case  of  some  diseases  of  a  previous 
attack,  the  state  of  health  of  the  individual,  and  hereditary  pre- 
disposition, are  well  known  to  determine  the  degree  of  bodily 
susceptibiHty ;  and  there  are  other  causes  at  work,  which  are  less 
well  known.  The  virulence  of  the  organism  at  the  time  it  enters 
the  body,  and  the  quantity  of  the  organisms  (dosage)  which  gain 
admission,  are  circumstances  which  may  determine  or  otherwise 
an  attack  of  the  disease. 

Among  the  diseases  of  animals  common  to  man,  in  which 
a  specific  bacterium  has  been  isolated,  are  anthrax  (malignant 
pustule  in  man),  tubercle,  glanders,  actino-mycosis,  erysipelas, 
tetanus,  plague,  foot-and-mouth  disease,  diphtheria,  and  malig- 
nant oedema. 

Anthrax,  Malignant  Pustule,  or  Wool-sorter's  Disease. — The 
bacilli  are  found  in  enormous  numbers  in  the  blood  of  animals 
dead  of  anthrax.  When  exposed  to  the  air  they  form  spores, 
which  are  much  more  resistant  to  extremes  of  heat  and  cold, 
to  drying,  and  to  chemical  reagents  than  the  fully  developed 
bacilli. 


THE   CONTAGIA  413 

Tubercle. — The  Bacillus  tuberculosis  is  found  in  all  tubercular 
deposits,  and  is  seen  with  a  high  power  of  the  microscope  to 
consist  of  small,  usually  straight  rods;  but  they  may  frequently 
be  slightly  curved.  The  bacilli  are  found  in  the  sputa  of  phthisical 
patients;  and  in  man  the  disease  is  set  in  action  by  the  bacilH 
introduced,  by  the  usual  method,  through  the  mucous  membrane 
of  the  air  passages  or  intestinal  canal,  through  the  tonsils  or 
genital  tract,  or  occasionally  by  direct  inoculation  into  a  wound 
or  abrasion  of  the  skin. 

In  the  lower  animals  (monkeys,  cattle,  fowls,  guinea-pigs, 
rabbits,  etc.)  artificial  tuberculosis  can  be  readily  produced  by 
inhalation  of  a  spray  containing  tubercle  bacilli,  by  feeding 
experiments  with  tuberculized  food,  and  by  direct  inoculation, 
the  channels  of  infection  being  the  same  as  those  of  man. 

The  question  of  susceptibihty,  hereditary  or  acquired,  to  the 
tubercular  virus  is  of  the  greatest  interest,  and  is  deserving  of 
most  careful  investigation.  It  is  evident  that  tubercle  bacilli 
must  be  very  widely  scattered  in  the  air  of  houses  and  towns, 
and  yet  the  number  of  persons  who  contract  tubercle,  and  show 
definite  symptoms  of  tubercular  infection,  is  very  small  com- 
pared with  the  numbers  that  must  from  time  to  time  be  exposed 
to  the  contagion.  The  very  large  proportion  of  adults,  who  have 
died  of  some  non-tubercular  disease  upon  whom  autopsies  have 
been  made,  and  whose  internal  organs  present  evidence  of  some 
old  tubercular  lesion,  either  caseated,  cicatrized,  or  otherwise 
cured  and  inactive,  is  evidence  of  the  widespread  diffusion 
amongst  civihzed  communities  of  the  tubercular  infecting  agent, 
and  of  the  general  resisting  powers  of  the  individuals  attacked  to 
the  more  fatal  forms  of  tuberculosis.  Unlike  the  eruptive  fevers, 
tubercular  diseases  run  no  definite  course ;  and  although  it  is  now 
certain  that  recovery  from  tubercular  lesions  of  the  lungs  and  of 
other  organs  is  by  no  means  infrequent,  yet  there  is  no  apparent 
immunity  conferred  from  subsequent  attack. 

Glanders. — The  bacillus  of  glanders  {Bacilhis  mallei)  consists  of 
rods  about  the  size  of  tubercle  bacilli.  The  inoculation  of  pure 
cultivations,  or  of  infectious  material  (e.g.,  pus),  from  an  infected 
horse  into  another  produces  the  characteristic  disease,  the  bacilli 
being  found  after  death  in  the  affected  organs  and  diseased 
tissues. 

In  erysipelas,  a  streptococcus  has  been  found  occupying  the 
lymphatics  of  the  skin  at  the  circumference  of  the  erysipelatous 


414  HYGIENE   AND  PUBLIC  HEALTH 

blush.  A  pure  cultivation  of  the  streptococci  produces  erysipe- 
latous inflammation  when  inoculated  into  animals  and  into 
men  (as  has  been  done  for  the  relief  of  lupoid  and  cancerous 
affections) ;  but  sometimes  suppuration  is  the  result  of  the 
injection,  and  it  is  now  believed  that  the  streptococcus  of 
erysipelas  and  the  Streptococcus  pyogenes  are  identical;  the 
different  effects  produced  being  dependent  upon : — 

1.  Mode  of  entry  and  site. 

2.  Resisting  power  of  the  tissues  at  the  time. 

3.  The  variable  virulence  of  the  streptococcus. 

The  specific  organism  in  tetanus  is  a  bacillus  which  probably 
exists  widely  distributed  in  dust,  dirt,  and  in  soil.  The  bacillus 
gains  an  entrance  into  the  body  through  scratches  and  wounds 
inflicted  by  substances  contaminated  with  dirt  containing  the 
organism  or  its  spores.  Cases  of  so-called  idiopathic  tetanus 
are  probably  due  to  similar  inoculations  through  scratches  or 
wounds  that  have  passed  unnoticed,  such  as  the  bite  of  an  insect, 
especially  in  the  tropics. 

Brieger,  Fraenkel,  and  others,  have  isolated  from  tetanus 
cultivations  two  toxic  substances,  tetanin  and  a  tox-albumin, 
both  of  which  produce  tetanic  symptoms  when  injected  into 
animals,  the  tox-albumin  being  far  more  deadly  than  the  tetanin. 
The  exact  nature  of  the  tetanus  toxin  is  still  doubtful,  but  there  is 
strong  evidence  in  favour  of  a  ferment  (diastase)  being  concerned 
in  its  production. 

Klebs,  Loeffler,  Roux,  and  Yersin  have  isolated  a  bacillus 
from  the  surface  of  the  mucous  membrane  in  cases  of  diphtheria. 
From  cultivations  of  this  bacillus  a  soluble  poison  has  been 
obtained,  which  causes  the  symptoms  of  diphtheria  in  varying 
degrees  of  intensity  according  to  the  dose.  This  poison  is  not 
an  alkaloid — a  ptomaine — but  appears  to  be  allied  to  the  fer- 
ments, as  it  is  precipitated  by  alcohol,  and  therefore  cannot  be 
of  alkaloidal  nature.  This  ferment  or  enzyme,  which  is  present 
in  the  false  membrane,  has  proteolytic  properties;  and  by 
digesting  the  proteid  material  in  the  membrane,  it  produces 
albumoses  and  an  organic  acid,  which  are  absorbed  into  the 
system,  and  to  which  the  toxic  symptoms  and  complications 
of  diphtheria  are  due  (S.  Martin). 

The  bacillus  of  typhoid  fever  (known  as  the  Eberth-Gaffky 
bacillujs)  is  constantly  present  in  the  ahmentary  canal,  in  the 
mesenteric  glands,  and  in  the  spleen  of  fatal  cases  of  this  disease. 


THE   CONTAGIA  4T5 

An  attempt  has  been  made  to  prove  the  identity  of  this  bacillus 
with  the  Bacillus  coll  communis,  which  is  a  constant  and  normal 
inhabitant  of  the  large  intestine  and  lower  portion  of  the  small 
intestines  of  man  and  mammalian  animals  under  perfectly 
healthy  conditions.  Dr.  Klein,  however,  has  shown  that  the  two 
bacilli  arc  morphologically  and  culturally  distinct.  Placed  in 
water,  the  two  bacilli  coexist  well  together;  but  the  Bacillus  coli 
is  capable  of  preserving  its  vitality  in  water  for  a  longer  period 
than  the  typhoid  bacillus.  In  sewage,  likewise,  the  Bacillus  coli 
flourishes,  whilst  the  typhoid  bacillus  gradually  diminishes  in 
numbers  and  ultimately  disappears.  The  cultural  characteristics 
of  the  two  bacilli  do  not  in  the  least  alter  during  their  sojourn 
in  water  or  sewage;  and  there  is  no  evidence  at  present  in 
support  of  the  view  that  the  Bacillus  coli  can  become  trans- 
formed into  the  typhoid  bacillus  whilst  sojourning  in  sewage  or 
elsewhere,  or  can  in  any  way  become  imbued  with  the  specific 
pathogenic  properties  of  the  latter  organism;  but  during  an 
attack  of  typhoid  fever,  the  Bacillus  coli,  normally  present  in 
the  bowels,  may  acquire  virulence,  and  be  the  cause  of  many  of 
the  complications  of  enteric  fever. 

In  Asiatic  cholera,  Koch  discovered  a  comma-shaped  bacillus 
in  the  intestinal  walls  and  evacuations.  In  relapsing  fever,  a 
motile  spirillum  {Spirillum  Obermeieri)  has  been  found  in  large 
numbers  in  the  blood  during  the  relapses,  which  organism  is 
absent  in  the  non-febrile  periods,  and  which,  when  inoculated 
into  monkeys,  induces  a  disease  analogous  to  human  relapsing 
fever.  It  is  probable  that  this  is  not  a  bacterium,  but  a  spiro- 
chaete  protozoon,  which  has  two  hosts — namely,  man  and  body 
lice,  and  is  conveyed  to  the  former  by  the  bite  of  the  latter. 
A  streptococcus  is  believed  to  be  the  specific  microbe  of  scarlet 
fever  (Klein) ;  and  various  micro-organisms  have  been  described 
as  associated  with  other  diseases. 

There  are  some  other  diseases  whose  microbic  origin  is  not 
yet  definitely  established,  but  in  which  there  is  a  very  strong 
probability  of  such  a  mode  of  occurrence.  Chief  among  these 
is  leprosy.  In  this  disease,  tine  rod-like  bacilli  are  found  in 
enormous  numbers  in  the  leprotic  nodular  lesions,  as  well  as  in 
some  of  the  internal  organs,  such  as  the  liver  or  spleen.  They 
spread  through  the  body  chiefly  by  means  of  the  lymphatics,  as 
they  are  only  occasionally  found  in  the  blood. 

From  vaccine  pustules  in  a  calf  and  from  human  vaccine 


4l6  HYGIENE   AND    PUBLIC   HEALTH 

lymph,  Klein  has  isolated  a  minute  bacillus,  which  is  probably 
the  specific  organism  of  vaccinia ;  and  Copeman  has  found 
similar  bacilli  in  stained  sections  of  vaccine  pustules.  Riiffer 
and  others  have  described  a  protozoon  in  the  epithelial  cells 
around  small-pox  and  vaccine  pustules.  From  acute  abscesses, 
boils,  carbuncles,  the  abscesses  of  pyaemia,  acute  osteomyelitis, 
a.nd  puerperal  fever,  the  Staphylococcus  pyogenes  aureus  and  alhus 
and  Streptococcus  pyogenes  have  been  obtained,  which  are  patho- 
genic to  certain  animals.  An  organism  (pneumococcus,  Fraenkel 
and  Weichselbaum)  has  been  found  in  the  exudations  of  croupous 
pneumonia,  which  is  pathogenic  to  mice,  inducing  a  very  acute 
septicaemia.  This  pneumococcus  or  diplococcus  is  also  said  to 
be  present  in  the  saliva  of  healthy  people  and  of  those  who  have 
suffered  from  pneumonia.  Its  presence  may  explain  the  Hability 
to  recurrence  of  this  disease,  in  association  with  chill  or  other 
exciting  cause.  In  ulcerative  {infective)  endocarditis  a  micrococcus 
has  been  observed  in  the  endocardial  ulcerations. 

Thus  there  is  still  wanting,  in  the  case  of  some  communicable 
diseases,  the  complete  chain  of  experimental  proof  necessary  to 
establish  the  causal  relationship  of  the  organisms  which  have 
been  described  as  associated  with  them.  The  experimental 
inoculation  of  the  lower  animals  with  the  supposed  vira  of  human 
diseases,  to  which  they  are  not  known  to  be  naturally  liable, 
affords  little  assistance  to  the  completion  of  the  proof,  even  if 
symptoms  are  produced  in  the  animal  of  an  analogous  nature 
to  those  characteristic  of  the  disease  in  man.  The  constant 
association  of  a  certain  organism  with  a  certain  disease,  in  all 
climates  and  races  of  men,  is,  no  doubt,  practically  a  strong 
point  in  favour  of  the  specific  nature  of  the  microbe,  but  logically 
it  does  not  prove  that  the  microbe  is  an  indispensable  antecedent 
(cause) ,  or  even  an  antecedent  (one  of  several  causes  in  con- 
j  unction)  of  the  disease,  or,  indeed,  that  it  is  anything  more 
than  a  consequence. 

Recent  research  seems  to  point  to  the  symptoms  of  infectious 
disease  being  caused  not  directly  by  the  action  of  the  microbes 
themselves  upon  the  tissues,  but  by  the  production  of  soluble 
poisons  of  the  nature  of  alkaloids,  and  in  some  cases  of  proteid- 
like  bodies,  such  as  albumoses,  termed  "  toxins."  Observations 
have  already  been  made  in  the  cases  of  anthrax,  tetanus,  diph- 
theria, puerperal  fever  and  rabies,  that  these  diseases  are — 
or  may  be — caused  by  the  specific  microbes  producing,  as  the 


THE   CONTAGIA  4I7 

result  of  their  activity,  these  soluble  poisonous  alkaloids  or  toxins, 
which  exert  a  direct  action  upon  the  tissues  of  the  body;  and 
if  such  is  the  case  in  these  diseases,  the  symptoms  of  many 
others  of  an  allied  nature  may  also  be  due  to  the  chemical  pro- 
ducts of  the  microbes,  and  not  to  the  direct  action  of  the  microbes 
themselves  upon  the  tissues. 

Immunity  and  Protection. — Immunity  is  either  natural  or 
acquired.  By  natural  immunity  is  meant  that  certain  species  of 
animals  or  certain  races  of  mankind  are  unaffected  by  certain 
diseases,  even  although  exposed  to  infection.  It  seems  probable 
that  this  condition  of  natural  immunity,  which  is  also  to  be  seen 
in  certain  individuals  of  species  or  races  which  themselves  are 
not  naturally  immune,  is  due  not  to  the  fact  that  the  specific 
micro-organisms  of  the  disease  are  inert,  subsequent  to  invasion 
of  the  body,  but  that  there  is  a  very  high  degree  of  resistance 
on  the  part  of  the  invaded  organism,  so  that  infection  is  not 
followed  by  any  effects  of  an  observable  nature. 

Immunity  is  acquired  by  the  individual  passing  through  an 
actual  attack  of  the  disease,  or  is  produced  artificially  by  pro- 
tective inoculations.  This  artificially  acquired  immunity  is  of 
two  kinds:  (i)  active,  (2)  passive. 

Active  immunity  against  a  disease  may  be  conferred  by  the 
injection  into  the  blood  or  tissues  of  the  living  specific  microbes 
of  that  disease  in  {a)  non-fatal  doses,  or  (b)  in  an  attenuated 
condition.  This  weakened  or  attenuated  condition  of  the  specific 
microbe  may  be  brought  about  by  (i)  growing  the  cultures  in  a 
current  of  air,  as  used  by  Haffkine  for  preparing  anti-cholera 
vaccine;  (2)  by  growing  the  cultures  at  abnormal  temperatures, 
as  used  for  attenuation  of  anthrax  by  growth  at  42°  to  43°  C; 
(3)  by  growing  the  cultures  in  media  to  which  some  weak  anti- 
septic (such  as  phenol  i  in  600)  has  been  added,  or  by  injecting 
such  antiseptic  along  with  the  organisms,  when  inoculating — as, 
for  example.  Gram's  iodine  solution  or  iodine  trichloride  is  added 
to  cultures  of  tetanus  before  inoculating  a  horse,  for  without  such 
attenuation  a  fatal  result  might  ensue;  (4)  by  drying  the  virus 
in  air,  as  in  the  Pasteur  system  of  inoculation  against  rabies; 
and,  lastly,  (5)  by  passing  the  specific  organism  through  the 
tissues  of  another  animal,  as  seen  in  the  calf-lymph  vaccination 
for  small-pox,  vaccinia  being  small-pox  attenuated  for  human 
beings  by  its  passage  through  the  calf. 

Active  immunity  may  also  be  conferred  by  the  injection  of 

27 


4l8  HYGIENE   AND   PUBLIC   HEALTH 

dead  cultures  of  the  specific  microbe  (enteric  fever  and  plague). 
The  immunizing  agent  in  such  dead  cultures  is  either  the  intra- 
cellular toxins — the  toxins  formed  within  the  cell  membrane  of 
the  bacteria — or  the  extracellular  toxins  produced  by  the  growth 
of  the  bacteria  in  the  culture  media  which  surround  them.  The 
former  are  obtained  by  collecting  the  growth  from  the  surface 
of  a  solid  medium  and  then  steriUzing  by  heat,  the  latter  by 
employing  the  filtrate  from  a  broth  culture  which  has  been  made 
to  traverse  a  germ-proof  filter. 

Passive  Immunity. — Passive  immunity  is  conferred  by  the 
injection  of  the  blood-serum  of  an  animal  which  has  been  actively 
immunized  by  any  one  of  the  above-mentioned  processes.  It  is 
termed  "  passive  "  because  the  individual  takes  no  part  in  the 
production  of  the  immunizing  agent.  Such  serum  may  be  anti- 
toxic — i.e.,  it  protects  the  animal  into  which  it  is  injected  from 
the  toxins  of  the  specific  microbe,  having,  however,  no  preven- 
tive action  on  the  living  micro-organism — or  it  may  be  anti- 
bacterial, preventing  the  multiplication  of  the  living  microbes, 
but  having  no  antitoxic  effects.  Some  sera  are  both  antitoxic 
and  antibacterial.  Passive  immunity  is  not,  as  a  rule,  lasting, 
whereas  active  immunity  may  be  of  considerable  duration. 

Phagocytosis. — The  role  of  the  body  cells  in  the  production  of 
immunity  was  discovered  by  Metchnikoff,  and  was  termed  by 
him  "  phagocytosis,"  meaning  the  capacity  displayed  by  certain 
amoeboid  cells  for  the  engulfing  and  subsequent  destruction  of 
micro-organisms,  red  blood-corpuscles,  cells,  and  cell  debris. 
Metchnikoff  classified  the  phagocytes  in  two  groups:  (i)  Macro- 
phages, (2)  Microphages,  the  former  consisting  of  the  "fixed" 
cells  of  the  spleen,  of  the  lymphatic  glands,  and  of  the  endothe- 
lium, their  activities  being  chiefly  directed  against  cells  and  cell 
debris;  whilst  the  latter  consist  of  the  "  free  "  or  "  wandering  " 
polymorphonuclear  leucocytes  of  the  blood,  whose  function  is 
the  destruction  of  micro-organisms.  It  is  the  latter  group  which 
appears  to  be  chiefly  concerned  in  the  production  of  immunity, 
as,  being  free,  they  are  able  to  make  their  way  to  any  part  of  the 
body  which  has  received  a  bacterial  infection,  and  there  undergo 
multiplication  on  a  large  scale  {leucocylosis) ,  so  as  to  be  able  to 
cope  with  the  invading  microbes. 

The  mere  presence  of  phagocytes  and  their  increased  numbers 
is  not,  however,  enough  by  itself  to  produce  phagocytosis  and  the 
conferring   of   immunity   by   the   destruction    of    the   invading 


THE   CONTAGIA  4T9 

bacteria.  Certain  other  bodies  must  have  made  their  appear- 
ance in  the  blood-serum  before  the  phagocytes  are  adequately 
endowed  with  their  powers  of  engulfing  and  destroying  bacteria. 
The  principal  of  tliese  anti-bacterial  substances  produced  in 
the  blood-serum  as  the  result  of  the  invasion  of  the  tissues  by 
bacteria  are: — 

Opsonins. — These  were  discovered  by  Wright  and  Douglas  in 
1903,  their  function  being  to  prepare  the  bacteria  for  ingestion  by 
the  phagocytes  {opsono  =  I  cater  for).  Opsonin  is  a  body  of 
unknown  constitution;  but  its  chief  properties  are,  in  addition 
to  rendering  the  bacteria  capable  of  absorption  by  phagocytes, 
(i)  its  instability,  as  it  disappears  from  serum  on  standing  after 
a  few  days;  (2)  its  capacity  for  being  injured  by  temperatures 
over  50° C,  and  its  destruction  by  heating  to  60°  C.  for  ten  minutes. 
It  is,  then,  what  is  known  as  thermolabile.  The  opsonin,  which 
is  produced  in  a  serum  as  the  result  of  an  invasion  by  a  specific 
bacterium  is  effective  only  for  that  bacterium,  and  for  no  other 
bacteria. 

Opsonins  are  normally  present  in  the  blood,  there  probably 
being  a  distinct  opsonin  for  each  possible  bacterial  invader  of  the 
body.  But  it  is  found  that  the  amount  of  any  specific  opsonin 
may  be  increased  by  injection  into  the  body  of  dead  cultures  of 
the  specific  microbe,  and  it  is  to  this  increase  that  may  be  ascribed 
the  immunizing  effect  of  such  injections.  For  a  short  period  after 
the  injection  there  is  a  "  negative  phase,"  but  this  is  rapidly 
succeeded  by  a  "  positive  phase,"  when  the  "  opsonic  index  "  is 
found  to  be  heightened.  The  "  opsonic  index  "  is  the  ratio  of 
the  average  number  of  specific  microbes  engulfed  in  a  phagocyte 
from  the  blood  of  any  individual  to  the  number  so  engulfed  in  a 
phagocyte  from  the  blood  of  a  normal  healthy  individual.  To 
obtain  this  index,  small  and  equal  quantities  of  (i)  the  blood- 
serum,  (2)  an  emulsion  of  the  organism  in  question,  and  (3)  leuco- 
cytes washed  free  from  plasma,  are  mixed  and  sealed  in  a  capillary 
tube,  and  then  incubated  at  37°  C.  for  fifteen  minutes.  Films 
are  then  prepared,  appropriately  stained,  and  examined  under 
the  microscope.  The  opsonic  index  is  largely  used  for  diagnostic 
purposes  in  tuberculosis,  in  which  disease  the  index  is  often  low 
or  very  irregular.  In  healthy  persons  the  index  is  more  regular, 
varying  in  individuals  from  o-8  to  i-2. 

Phagocytosis  and  the  opsonic  powers  of  blood-serum  have  been 
studied  chiefly  in  connection  with  invasions  of  the  body  by  the 


420  HYGIENE   AND   PUBLIC   HEALTH 

following  organisms:  Staphylococcus,  Bacilhis  tuberculosis,  B.  pes- 
tis,  B.  melitensis,  B.  dysentericus  (Shiga),  B.  coli,  Pneum)coccus, 
Streptococcus,  B.  anthracis,  B.  typhostis,  and  Vibrio  cholercB.  B. 
diphthericB  appears  not  to  be  affected  by  opsonins;  and  in  regard 
to  all  the  above  infections  it  must  be  borne  in  mind  that  the 
question  of  phagocytability  is  dependent  upon  virulence  very 
largely,  a  freshly  isolated  virulent  bacterium  being  frequently 
quite  resistant  to  phagocytosis,  whilst  the  same  bacterium,  which 
has  been  sub-cultured  in  nutrient  media,  may  be  phagocyted 
with  facility.  Some  of  the  infective  agents  of  disease  appear 
also  to  be  capable  of  defending  themselves  against  the  immunity 
producing  forces  of  the  body,  and  of  eventually  producing 
resistant  strains,  which  can  perpetuate  the  race,  uncontrolled  by 
the  defensive  powers  of  the  host.  In  certain  cases  the  resistant 
strains  would  appear  to  have  provided  themselves  with  capsules, 
which  enable  them  to  resist  destruction  by  the  cells  and  fluids 
of  the  host.  These  strains  are  probably  the  result  of  natural 
selection  and  the  survival  of  the  fittest.  Such  occurrences  of 
"  resistant  strains  "  are  believed  to  occur  in  trypanosomiasis, 
syphilis,  relapsing  fever,  streptococcus  and  pneumococcus  in- 
fections, enteric  fever,  and  anthrax;  and  they  afford  explana- 
tions of  many  of  the  phenomena  of  these  affections,  which  are 
characterized  by  much  variability  of  symptoms,  relapses,  and 
extreme  chronicity. 

Agglutinins.— These  are  substances  produced  in  the  blood- 
serum  as  the  result  of  the  invasion  of  infective  bacteria,  which 
cause  the  particular  bacteria,  in  response  to  which  they  appear, 
to  agglutinate,  i.e.,  to  lose  their  motility,  if  they  are  motile,  and 
to  collect  into  clumps,  which,  outside  the  body  {in  vitro),  separate 
out  from  the  fluid  and  deposit  at  its  lowest  part.  The  bacteria 
are  not  killed  by  agglutination.  Although  these  agglutinins  are 
specific  for  specific  bacteria,  they  also  appear  to  be  able  to  exert 
a  partial  agglutinizing  effect  upon  bacteria  of  alHed  species. 
Thus  a  typhoid  immune  serum  possesses,  besides  its  greatly 
increased  agglutinating  power  for  B.  typhosus,  an  agglutinating 
power  in  less  degree  for  B.  paratyphosus,  which  is  notably  above 
the  agglutinating  power  of  normal  serum  for  the  latter  microbe. 

The  role  played  by  the  agglutinins  in  the  production  of  immunity 
appears  to  be  slight,  as  neither  the  capacity  for  growth,  nor  the 
virulence  of  the  agglutinated  bacteria,  is  appreciably  altered 
thereby    The  agglutinating  power  of  the  serum  of  an  animal 


THE   CONTAGIA  421 

gives  no  indication  of  the  degree  of  the  animal's  immunity  against 
the  particular  micro-organism.  Nevertheless,  the  presence  of 
agglutinins  in  a  scrum  affords  valuable  indications,  (i)  in  the 
diagnosis  of  various  bacterial  diseases,  (2)  in  the  differentiation 
of  bacteria  found  in  various  lesions.  Agglutinins  exert  their 
effects  upon  dead  as  well  as  upon  living  bacteria. 

Precipitins. — These,  like  the  agglutinins,  are  specific  substances 
found  in  the  serum  of  animals  which  have  received  injections  of  a 
particular  micro-organism,  or  of  solutions  of  animal  or  vegetable 
albumins.  These  precipitins,  when  introduced  into  a  clean 
culture  filtrate  of  the  specific  (homologous)  micro-organism,  or 
into  a  clear  solution  of  the  particular  albumin,  which  gave  rise 
to  them,  produce  a  precipitate.  Like  the  agglutinins,  the  pre- 
cipitins probably  play  but  a  very  small  part  in  the  production 
of  immunity.  They  have,  however,  much  interest  for  medico- 
legal purposes,  and  especially  for  determining  the  origin  of  blood 
stains.  Thus,  by  injecting  rabbits  with  the  blood  of  man  or  other 
animals,  sera  can  be  obtained  which  give  a  precipitate  in  the 
serum  of  the  blood  used  for  the  injection,  but  not  in  the  serum 
of  other  kinds  of  blood.  The  precipitin  reaction  is  also  found  to 
be  common  for  the  sera  of  animals  of  closely  related  species ;  thus, 
the  sera  of  anthropoid  apes  give  the  reaction  when  the  rabbit  has 
been  injected  with  human  blood;  and  a  similar  relationship  has 
been  observed  between  the  sera  of  the  horse  and  the  ass,  the 
sheep  and  the  cow,  the  hare  and  the  rabbit,  and  the  hen  and  the 
pigeon. 

Bacteriolysins. — These  are  specific  substances  found  in  the 
blood  of  animals  which  have  been  immunized  against  a  specific 
bacterium.  They  cause  the  specific  bacteria  to  shrivel  up  and 
eventually  to  become  converted  into  granules,  at  the  same  time 
rendering  motile  bacteria  immotile,  and  depriving  them  of  their 
staining  properties.  The  effective  agent  of  these  bacteriolysins 
is  a  substance  which  was  called  by  Ehrlich  "  amboceptor,"  because, 
on  the  one  hand,  it  attaches  itself  to  the  bacterium,  and.  on  the 
other,  to  the  substance  called  "  ccmplemcnt,"  which  must  be 
present  in  the  serum,  and  capable  of  attachment  through  the 
amboceptor  to  the  bacterium,  if  bacteriolysis  is  to  take  place. 
The  amboceptor  is  thermostable,  i.e.,  resists  heating  at  55°  C.  for 
one  hour,  and  is  specific  for  the  particular  kind  of  bacterium  in 
response  to  which  it  has  been  produced;  whilst  complement  is 
thermolabile  (destroyed  by  heating  for  half  an  hour  at  55°  C.)  and 


422  HYGIENE    AND    PUBLIC   HEALTH 

is  non-Specific,  being  present  in  the  blood  of  non-immunized 
animals,  and  not  being  increased  during  the  process  of  immuniza- 
tion. Complement  will,  therefore,  unite  with  any  specific  ambo- 
ceptor and  its  corresponding  bacterium ;  but  it  disappears  spon- 
taneously within  a  few  days  from  serum  withdrawn  from  the  body. 
A  serum  is  said  to  be  "  inactivated  "  when  its  complement  has 
been  destroyed  by  heating  to  55°  C.  Not  all  bacteria  are  subject 
to  bacteriolysis.  It  is  limited  chiefly  to  the  typhoid  and  para- 
typhoid groups  and  the  cholera  organism.  The  part  played  by 
bacteriolysins  in  the  production  of  immunity  is  not  yet  fully 
understood. 

Hcemagglutinins. — These  are  substances,  similar  to  bacterial 
agglutinins,  which  are  produced  in  the  serum  of  an  animal  which 
h;is  been  inoculated  with  the  red  blood  corpuscles  of  another 
species.  Such  serum  mixed  with  a  suspension  of  the  correspond- 
ing red  blood  corpuscles  causes  these  to  clump  and  sink  to  the 
bottom. 

HcEnulysins. — These  are  substances  similar  to  the  bacterio- 
lysins, which  are  produced  in  the  serum  of  an  animal  which  has 
been  inoculated  with  the  red  blood  corpuscles  of  another  species. 
Such  serum  mixed  with  a  suspension  of  the  corresponding  red 
blood  corpuscles  causes  the  latter  to  lake — their  envelopes  are 
ruptured,  and  the  haemoglobin  escapes  into  the  fluid,  which 
becomes  uniformly  tinged  red,  the  altered  corpuscles  sinking  to 
the  bottom  of  the  fluid. 

Like  the  bacteriolysins,  the  haemolysins  are  amboceptors. 
They  are  unaffected  by  a  temperature  of  55°  C. ;  and  they  are 
inert  unless  complement  is  present,  and  free  to  unite  with  them. 
They  are  also  specific  for  the  particular  red  blood  corpuscles  in 
response  to  which  they  have  been  produced. 

Haemolysins  are  of  special  interest  in  connection  with  the 
Wassermann  reaction  for  the  diagnosis  of  syphilis.  For  carrying 
out  this  test  the  following  substances  are  required,  viz. :  (i)  The 
antigen;  (2)  the  patienf  s  serum ;  (3)  complement;  (4)  red  blood 
corpuscles  ;  (5)  hcemolytic  amboceptor. 

Antigen  is  the  name  given  to  a  substance  which,  when  intro- 
duced into  an  animal  body,  gives  rise  to  the  formation  of  an 
antibody.  Antigen  may  be  a  toxin,  a  bacterial  emulsion,  a 
bacterial  extract,  an  emulsion  of  blood  corpuscles,  a  solution  of 
albumin,  etc.  The  antigen  originally  used  for  the  test  was  a 
watery  extract  of  the  liver  of  a  syphilitic  foetus;  but  it  has  now 


THE   CONTAGIA  423 

been  found  that  alcoholic  extracts  of  normal  organs  yield  an 
antigen  which  is  as  effective  as  the  syphilitic  foetal  liver.  Com- 
plement is  obtained  from  fresh  guinea-pig  serum.  The  blood 
corpuscles  are  obtained  from  defibrinated  sheep's  blood,  and  are 
centrifugalized  and  washed  in  normal  saline  solution,  so  as  to 
free  them  from  serum.  Hsemolytic  amboceptor  is  obtained  from 
the  serum  of  a  rabbit  which  has  been  injected  with  the  washed, 
red  blood  corpuscles  of  a  sheep. 

The  patient's  serum,  the  complement,  and  the  antigen  are 
mi.xed  in  a  tube  in  suitable  dilutions,  and  placed  in  an  incubator 
at  2>7°  C.  for  one  hour.  The  haemolytic  amboceptor  and  the  sus- 
pension of  sheep's  corpuscles  in  suitable  dilutions  are  then  added, 
and  the  mixture  incubated  for  two  hours  at  37°  C.  After  twelve 
hours  of  standing  in  the  cool,  the  result  may  be  observed.  If 
the  serum  is  from  a  syphilitic  patient,  the  complement  has  fixed 
itself  to  the  syphilitic  antibody  or  amboceptor  present  in  his 
serum,  which  is  itself  attached  to  the  antigen,  and  no  haemolysis 
results,  all  the  blood  corpuscles  being  found  at  the  bottom  of  the 
tube,  leaving  the  fluid  above  clear  and  colourless.  If  the  patient 
is  not  syphilitic,  haemolysis  takes  place,  as  the  complement  is  free 
to  unite  with  the  hasmolytic  amboceptor,  there  being  no  specific 
amboceptor  present;  and,  as  a  result,  no  corpuscles  are  found  at 
the  bottom  of  the  tube,  and  the  fluid  becomes  deeply  "  laked  "  or 
stained  with  haemoglobin.  Between  the  two  results  of  complete 
positive  reaction  and  complete  negative  reaction,  various  grades 
may  be  found,  dependent  upon  the  stage  of  the  disease  reached, 
and  the  corresponding  presence  of  syphilitic  antibodies  in  the 
patient's  serum. 

Antitoxins.— These  are  antibodies  produced  in  the  blood  of  an 
animal  in  response  to  the  injection  of  bacterial  toxins,  or  as  the 
result  of  the  natural  invasion  of  the  body  by  a  toxin-producing 
bacterium.  Each  antitoxin  is  specific,  and  is  effective  only 
against  the  toxin  produced  by  the  particular  bacterium  in 
response  to  which  it  appears.  Toxins  are  the  result  of  growth 
of  bacteria  of  certain  'kmdi?,  {Bacillus  diphiherice,B.  tetani,B.  dyscn- 
tericB,  and,  to  a  less  extent,  B.  typhosus.  Vibrio  cholerce,  and 
Meningococcus)  either  within  the  animal  organism,  or  in  culture 
fluids  outside  the  body.  For  the  most  part  they  are  secretion 
products  of  the  bacteria,  which  are  given  off  into  the  medium  in 
which  the  bacteria  are  growing.  Such  are  known  as  exotoxins. 
It  is  thought  by  some  that  there  are  also  endotoxins  (formed 


424  HYGIENE   AND   PUBLIC   HEALTH 

within   the  bodies   of   the   bacteria),   but   this   appears    to    be 
doubtful. 

Antitoxin  neutrahzes  or  renders  inert  its  own  toxin;  and  this 
effect  is  produced  both  in  the  body  itself,  as  in  the  well-known 
result  following  the  injection  of  diphtheria  antitoxin  into  persons 
suffering  from  this  disease,  and  also  in  vitro,  or  outside  the  animal 
body,  as  can  be  seen  by  mixing  antitoxin  serum  with  a  lethal  dose 
of  diphtheria  toxin,  and  then  injecting  into  a  guinea-pig.  The 
exact  method  by  which  antitoxin  neutralizes  toxin,  so  that  the. 
latter  loses  its  effects  on  the  tissues,  is  unknown.  The  com- 
bination of  toxin  with  antitoxin  may  partake  of  the  nature  of  a 
chemical  reaction,  or  it  may  be  that  a  physical  effect  is  produced, 
on  the  supposition  that  toxin  and  antitoxin  are  bodies  in  a  colloid 
state,  which  may  combine  so  as  to  neutralize  each  other  without 
any  chemical  union. 

In  diseases  such  as  diphtheria,  tetanus,  and  bacillary  dysentery, 
where  toxins  are  largely  produced  at  the  site  of  local  lesions,  and 
thence  absorbed  into  the  circulation,  the  production  of  immunity 
is  intimately  connected  with  the  formation  of  antitoxins  in  the 
blood  in  response  to  the  stimulus  of  the  toxins  locally  secreted. 
In  most  other  diseases  of  an  infective  character,  phagocytosis  and 
the  production  of  antibodies  in  the  serum,  which  assist  or  render 
phagocytosis  effective,  would  appear  to  be  more  intimately  con- 
cerned with  the  production  of  immunity  than  antitoxin  formation. 
It  seems  probable,  however,  that  in  all  diseases  of  this  class  which 
confer  some  degree  of  immunity  to  subsequent  attack,  the  de- 
fensive powers  of  the  body  may  be  concerned  both  in  phagocy- 
tosis and  in  antitoxin  formation,  the  relative  activities  of  each 
varying  with  the  nature  of  the  disease,  the  stage  of  the  disease, 
and  the  dosage  and  virulence  of  the  infecting  organism. 

Infections  of  the  human  body  may  be  broadly  conceived  as 
being  of  two  classes:  (i)  generalized,  and  (2)  localized.  There 
is  no  true  dividing  line  between  the  two,  as  generalized  infec- 
tions may  become  localized,  or  vice  versa  ;  but  in  the  former 
the  blood  is  invaded  by  the  organism,  and  a  general  systemic 
infection  results,  whilst  in  the  latter  the  organism  is  more  or 
less  restricted  to  a  certain  localized  area ;  and  although  organisms 
may  at  times  travel  beyond  the  infected  area,  and  enter  the 
blood-stream,  the  symptoms  of  illness  are  more  attributable  to 
the  absorption  of  toxins  from  such  area  than  to  bacillary  in- 
vasion of  the  systemic  circulation.  The  localization  of  the 
invading  microbes  is  for  the  most  part  effected  by  inflammatory 


THE   CONTAGIA  425 

processes  in  and  around  the  site  of  invasion,  which  tend  to  cir- 
cumscribe the  mischief  by  preventing  any  large  access  of  the 
invaders  to  the  blood  and  circulation.  The  well-known  dangers 
of  infections  of  the  general  septicaemic  type  are  probably  due  to 
rapid  multiphcation  of  the  invaders  in  the  blood  and  tissues, 
and  the  production  of  toxins  in  dangerous  quantities  before  the 
resisting  powers  of  the  body  and  the  protective  actions  of  opsonins 
and  phagocytes  can  be  brought  into  play.  In  such  cases  curative 
inoculations  with  dead  or  Uving  cultures  of  the  specific  bacteria 
would  probably  have  a  deleterious  effect,  as  the  ensuing  "  nega- 
tive phase  "  would  only  heighten  the  dangers  of  toxin-poisoning 
already  in  progress;  but  injections  with  sera,  having  anti- 
bacterial properties,  might  here  serve  a  useful  purpose. 

In  the  more  chronic  locahzed  infections,  such  as  acne,  boils, 
carbuncles  (Wright),  where  there  is  failure  to  overcome  the 
invading  microbe,  owing  to  the  very  success  which  has  attended 
the  inflammatory  processes  in  their  endeavours  to  isolate  the 
virus  at  the  site  of  entry,  curative  inoculations  with  suspensions 
of  the  dead  bacilli  have  been  found  highly  beneficial,  as  they 
appear  to  enable  the  phagocytes  to  penetrate  into  the  inflamed 
area,  and  there  attack  the  invaders  in  their  entrenched  position. 

The  best  curative  results  are,  however,  seen  in  the  case  of  the 
diseases,  such  as  diphtheria  and  tetanus,  in  which  the  symptoms 
are  due  to  toxins  absorbed  from  the  specific  microbes  which  are 
themselves  localized — in  the  fauces  (diphtheria)  or  at  the  site  of 
entry  of  the  virus  in  a  wound  (tetanus).  If  injected  sufficiently 
early  in  the  disease  before  toxin  formation  has  been  carried  to  a 
dangerous  length,  the  early  arrest  of  the  disease  may  be  relied 
upon.  Injections  of  diphtheria  antitoxin  are  also  employed  for 
immunizing  purposes  in  the  case  of  diphtheria"  contacts  "  and 
"  carriers."  The  immunization  so  produced  is  dependent  upon 
the  extent  to  which  the  serum  is  anti-microbic  as  well  as  anti- 
toxic, and  is  no  doubt  of  an  evanescent  character;  but  it  may 
be  sufficient  to  confer  immunity  for  a  period,  when  there  is  a 
considerable  risk  of  infection ;  and  in  the  case  of  "  carriers  "  it 
may  prevent  the  Klebs-Loeffler  bacillus  present  in  the  faucial 
or  nasal  mucous  membranes  from  effecting  such  a  lodgment 
or  assuming  such  virulence  as  to  eventuate  in  a  diphtheritic 
attack. 

Anaphylaxis. — If  an  animal  is  injected  with  an  albuminous 
substance,  such  as  the  serum  of  an  animal  of  a  different  species, 
organic  extracts,  bacterial  extracts,  etc.,  a   second  injection  of 


426  HYGIENE    AND    PUBLIC    HEALTH 

similar  material  will  produce,  after  a  definite  period,  what  arc 
known  as  symptoms  of  anaphylaxis.  A  state  of  hypersensitive- 
ness  is  induced  to  which  the  body  reacts  on  the  second  injection. 
The  incubation  period — -i.e.,  the  interval  elapsing  between  the 
first  or  "  sensitizing"  injection  and  the  date  at  which  anaphylactic 
phenomena  may  occur — -appears  to  vary  with  the  original  dose. 
If  this  has  been  small,  the  incubation  period  may  be  short — 
eight  to  twelve  days;  if  the  dose  has  been  a  large  one,  the  period 
may  be  one  of  weeks  or  months.  Should  a  second  fairly  large 
dose  be  given  before  the  end  of  the  incubation  period,  the  animal 
is  de-sensitized,  or  rendered  immune  to  anaphylaxis.  In  man 
the  chief  symptoms  of  anaphylaxis  are  oedema  at  the  point  of 
injection,  nausea,  vomiting,  dyspnoea,  fever,  muscular  and 
articular  pains,  and  depression,  followed  later  by  urticarial 
eruptions  accompanied  by  much  itching,  glandular  swellings, 
and  inflammations  of  mucous  membranes.  These  symptoms 
may  come  on  within  four  to  six  hours  from  the  second  injection, 
or  be  delayed  for  several  days  (five  to  fifteen).  These  anaphy- 
lactic symptoms  are  probably  due  to  antibodies  formed  in  the 
blood  as  the  result  of  the  first  injection,  which,  on  the  second 
injection,  unite  with  the  albuminous  substance  (antigen)  intro- 
duced into  the  system ;  and  this  union  of  antibodies  with  antigen 
is  thought  to  be  capable  of  developing  marked  toxic  capacity. 
The  incubation  period  is  necessary  for  the  formation  of  anti- 
bodies in  sufficient  quantity  to  unite  with  the  antigen  of  the 
second  injection. 

Anaphylaxis  in  the  human  subject  is  of  interest  in  connection 
with  serum  therapy,  and  especially  with  diphtheria  antitoxin, 
the  vehicle  for  which  is  horse-serum.  Fresh  serum  is  more 
toxic  in  this  respect  than  serum  which  has  been  kept;  so  it  is 
a  good  rule  not  to  use  any  serum  for  therapeutic  purposes  which 
is  less  than  two  months  old.  The  toxicity  may  also  be  diminished 
by  intermittent  heating.  The  possibility  of  the  subsequent 
production  of  anaphylaxis  is  an  objection  to  the  giving  of  anti- 
toxin as  a  prophylactic  to  ward  off  diphtheria.  Should  a  child 
so  immunized  subsequently  develop  the  disease  more  than 
twelve  days  after  the  prophylactic  injection,  there  will  be  a 
danger  of  anaphylactic  phenomena  showing  themselves  after 
the  first  injection  of  antitoxin  for  curative  purposes.  The 
anaphylactic  symptoms  are  occasionally  very  serious,  and  may 
even  cause  death. 


THE   CONTAGIA  427 

Within  the  last  few  years  it  has  been  shown  by  Behring, 
Kitasato,  Hankin,  Tizzoni,  and  Cattani,  that  animals  may  be 
rendered  immune  to  diphtheria,  tetanus,  septic  infections,  and 
many  other  diseases,  viz.,  plague,  pneumonia,  typhoid  fever, 
cholera,  anthrax,  and  quarter  evil,  by  repeated  subcutaneous 
injections  of  the  toxins  produced  when  the  specific  microbes 
of  these  diseases  are  grown  in  suitable  culture  media.  The 
toxins  in  the  culture  liquids  are  made  to  pass  through  a 
porcelain  filter,  before  injection,  in  order  that  all  microbes  may 
be  arrested.  When  the  process  of  immunization  is  complete — 
several  months  being  usually  required  to  attain  completion  by 
means  of  graduated  injections,  so  that  the  health  of  the  animal 
(usually  a  horse)  may  not  seriously  suffer — the  serum  of  the 
blood  is  found  to  possess  antitoxic,  i.e.,  defensive,  properties 
against  the  toxins  of  the  particular  disease.  The  blood  of  the 
animal  is  accordingly  drawn  off  from  a  large  vein,  and  the  serum 
separated  with  all  proper  aseptic  precautions,  and  finally  stored 
for  use.  Not  only  has  the  serum  the  power  for  a  varying  period 
of  conferring  immunity,  when  injected  into  the  human  body, 
against  subsequent  attack,  but  it  also  has  the  power  of  arresting 
the  disease  already  commenced,  if  employed  within  a  short  period 
of  onset.  As  is  now  well  known,  diphtheria  antitoxic  serum  has 
been  widely  used,  and  has  met  with  great  success,  in  the  treat- 
ment of  diphtheria;  and  the  treatment  of  tetanus  by  antitoxic 
serum  has  been  successfully  inaugurated.  The  treatment  of 
septicaemia,  puerperal  fever,  erysipelas,  scarlet  fever,  rheumatic 
fever,  and  ulcerative  endocarditis  by  antistreptococcic  serum, 
and  of  acute  pneumonia  by  antipneumococcic  serum,  would  also 
probably  prove  more  successful,  were  not  these  diseases  very 
often  the  result  of  infection  by  more  than  one  species  of  micro- 
organism. Animals  have  also  been  immunized  against  ricin 
and  abrin  (two  vegetable  poisons)  and  against  snake  poison.  In 
all  these  cases  antitoxic  sera  have  been  obtained,  some  of  which 
are  of  undoubted  utilit3^  whilst  others  are  still  only  in  the 
experimental  stage.  Different  observers  claim  to  have  prepared 
sera  protecting  against  yellow  fever,  syphilis,  infection  with  the 
Staphylococcus  pyogenes  aureus  and  with  Bacillus  coli  ccmniunis, 
and  rabies.     These  claims,  however,  require  confirmation. 

Tuberculin  and  mallein  are  substances  obtained  by  growing 
the  Bacillus  tuberculosis  and  Bacillus  mallei  in  glycerine  veal  or 
beef  broth  for  several  weeks,  and  then  filtering  off  the  organisms. 


428  HYGIENE   AND    PUBLIC   HEALTH 

Tuberculin  is  used  for  diagnostic  purposes  both  in  men  and  cattle, 
and  is  now  coming  largely  into  use  for  the  treatment  of  tuber- 
culosis in  man.  The  tuberculin  for  treatment  is  derived  either 
from  human  or  bovine  sources.  Sufficient  time  has  not  yet 
elapsed,  since  this  treatment  came  into  use,  to  enable  us  to  say 
whether  bovine  or  human  tuberculin  has  the  best  curative 
results.  There  can  be  no  question,  however,  that  tuberculin 
injections  carefully  carried  out  in  suitable  cases  have  consider- 
able effects  in  raising  the  resisting  power  of  the  body  to  the  toxins 
produced  by  the  invading  bacillus.  On  the  other  hand,  the 
effect  of  tuberculin  injections  on  the  disease  foci  in  the  body  is 
often  disappointing.  Mallein  is  extensively  used  in  veterinary 
practice  for  the  diagnosis  of  glanders. 

The  following  is  a  list  of  diseases  in  which  preventive  inocula- 
tions are  employed:- — -Anthrax,  bubonic  plague,  chicken  cholera, 
Asiatic  cholera,  diphtheria,  dysentery,  glanders,  hog  cholera, 
hog  erysipelas,  hydrophobia,  meningitis,  pleuro-pneumonia  in 
cattle,  pneumonia,  swine  plague,  streptococcus  infection,  sympto- 
matic anthrax  or  quarter  evil,  tetanus,  tuberculosis,  and  typhoid 
fever  (Sternberg). 

The  serum  diagnosis  of  acute  specific  fevers  has  attracted 
much  attention,  more  especially  in  relation  to  Malta  fever  and 
enteric  and  paratyphoid  fever.  Durham  and  Gruber  have 
shown  that  whenever  the  micro-organisms,  which  are  causally 
associated  with  these  diseases,  are  brought  into  contract  with 
the  diluted  serum  or  plasma  of  an  animal  or  a  patient  who  is 
undergoing,  or  has  recently  undergone,  an  attack  of  the  disease 
in  question,  the  following  succession  of  phenomena  (or  some  of 
them)  manifest  themselves:  (i)  The  bacteria  become  agglutin- 
ated, or  clump;  (2)  the  bacteria  lose  their  motility;  (3)  the  clumps 
of  agglutinated  bacteria  sink  to  the  bottom  of  the  tube,  and  the 
culture  fluid,  which  was  previously  evenly  turbid,  becomes 
clarified;  (4)  the  bacteria  shrink  up  into  the  form  of  minute 
spherules;  (5)  the  bacteria  are  definitely  devitalized.  This 
method  is  now  being  extended  to  the  diagnosis  of  other  diseases, 
especially  infection  with  Gaertner's  bacillus,  Bacillus  pyocyaneus, 
and  glanders  in  horses;  also  to  cholera  and  plague. 

The  possibility  of  insects  carrying  pathogenic  organisms  has 
been  demonstrated  in  the  case  of  anthrax,  plague,  zymotic 
diarrhoea  and  cholera,  and  less  certainly  in  the  case  of  typhoid 
fever   and   Egyptian   ophthalmia.     Blood-sucking   insects   may 


COMMUNICABLE    DISEASES  429 

transmit  disease  directly  from  the  sick  to  the  healthy  {see 
Tropical  Diseases),  and  such  a  mode  of  transmission  is  possible 
in  anthrax,  septicaemia,  pyaemia,  erysipelas,  leprosy  and  tuber- 
culosis. The  matter  is  still  sub  judice,  but  there  are  good  grounds 
for  the  belief  that  these  and  other  diseases  may  occasionally  be 
thus  communicated. 

It  has  been  demonstrated  beyond  doubt  that  the  mosquito 
is  the  means  of  conveying  the  malarial  parasite,  the  embryo 
filaria  sanguinis  hominis,  and  the  infection  of  yellow  fever  from 
one  individual  to  another. 

Insects,  moreover,  may  transport  the  eggs  of  animal  parasites 
{Tcenia  solium,  Tricocephalus  dispar,  A  scar  is  lumhricoides,  etc.), 
and  deposit  them  on  food. 

Communicable    Diseases. 
Small-pox  and  Vaccination. 

The  incubation  period  of  small-pox  is  nearly  always  twelve 
days,  but  may  vary  from  nine  to  fifteen.  When  the  virus  has 
been  inoculated,  the  incubation  is  said  to  be  shorter — only  seven 
or  eight  days.  The  incubation  period  of  variola  nigra  is  said  to 
be  only  six  or  seven  days.  Small-pox  is  probably  communicable 
from  the  earliest  appearance  of  the  symptoms,  and  the  ordinary 
duration  of  infectiveness  is  from  three  to  four  weeks.  The 
virus  is  contained  in  the  mouth  and  throat  secretions  of  the 
patient  and  in  the  skin  eruptions,  and  is  capable  of  being  con- 
veyed for  considerable  distances  through  the  air  in  the  dried 
epithelial  scales  and  pus  cells  from  the  crusted  pocks. 

The  exceptional  incidence  of  small  -  pox  in  the  immediate 
neighbourhood  of  some  small  -  pox  hospitals,  in  which  were 
treated  during  epidemic  periods  large  numbers  of  cases,  serves 
to  demonstrate  that  the  hospital  is  hable  to  become  a  centre  of 
infection  to  the  surrounding  neighbourhood.  In  the  diagram 
(fig.  78)  taken  from  Mr.  Power's  Report  to  the  Local  Government 
Board,  1885,  the  neighbourhood  around  the  Fulham  Small- 
pox Hospital  is  divided  into  special  areas  by  circles  of 
J,  I,  I,  and  I  mile  radii.  In  these  special  areas  the  figures 
show  the  percentage  of  houses  in  each  area  invaded  by  small- 
pox in  the  period  May  25,  1884,  to  September  26,  1885.  The 
extreme  incidence  of  the  disease  in  the  J  mile  circle  surrounding 
the  hospital  is  at  once  apparent,  and  is  attributed  by  Mr.  Power 


430 


HYGIENE  AND  PUBLIC  HEALTH 


to  the  aerial  diffusion  of  the  infection.  The  exceptional  in- 
cidence in  the  quadrant  lying  south-east  of  the  hospital  is  note- 
worthy, and  this  has  been  attributed  to  the  greater  prevalence 
of  north-westerly  winds  during  the  period  included.  But  it 
should  be  stated  that  this  central  J  mile  circle,  containing,  as 
it  did,  only  a  few  hundred  houses,  was  somewhat  exceptionally 
liable  to  be  capriciously  affected. 
Dr.  Barry's  report  on  the  small-pox  epidemic  at  Sheffield  also 

N 


FuLH.\M  Sm.\ll-pox  Hospital. 


Special  area  divided  into  sections  of  ^,  ^,  J,  and  i  mile  radii,  showing  in 
different  areas  the  number  of  houses  (out  of  every  loo)  invaded  by 
small-pox,  in  the  period  May  25,  1884,  to  September  26,  1885. 

shows  that  the  small-pox  hospital,  situated  in  a  thickly  popu- 
lated locality  in  the  centre  of  the  town,  was  instrumental  in 
disseminating  the  disease  in  the  "  special  area  "  surrounding 
the  hospital,  as  soon  as  a  number  of  acute  cases  were  concen- 
trated in  it.  But  when  the  patients  were  removed  to  a  new 
hospital  erected  outside  the  borough,  the  excessive  incidence  of 
the  disease  upon  the  area  surrounding  the  old  hospital  disap- 
peared.     Whether    small  -  pox    in    these    cases   is    transmitted 


COMMUNICABLE    DISEASES  43I 

aerially  or  by  personal  communication  has  been  the  subject 
of  much  controversy,  as  the  faulty  administration  of  the  hospital 
may  have  allowed  the  transmission  of  small-pox  in  the  persons  of 
the  hospital  staff,  or  of  visitors  to  the  hospital. 

Dr.  Arnold  Evans  has  shown  the  influence  of  the  Bradford 
Fever  Hospital  in  1893  in  disseminating  small-pox  in  the  special 
area  around  it.  The  percentage  incidence-rate  on  houses  within 
the  I  mile  radius  was  10-4;  on  houses  within  the  j  to  ^  mile 
area  6-8;  on  houses  within  the  |  to  |  mile  area  2-i;  and  on 
houses  within  the  |  to  i  mile  area  i-o.  The  incidence  rate  on 
the  whole  borough  during  the  period  was  o-6  per  cent.  The 
quadrant  lying  north-east  of  the  hospital  in  the  special  i  mile 
area  suffered  most — 7*06  per  cent,  of  houses  invaded;  then 
followed  the  south-east  quadrant,  5-28  per  cent.;  the  south- 
west quadrant,  293  per  cent.;  and  the  north-west  quadrant, 
24  per  cent.  It  is  recorded  that  on  250  days  of  that  year  the 
prevailing  winds  were  westerly,  and  only  on  eighty-three  days 
was  the  wind  persistently  from  the  east. 

After  reviewing  all  the  circumstances.  Dr.  Evans  formed 
the  opinion  that  the  most  likely  manner  to  account  for  the 
extensive  prevalence  of  small-pox  over  the  special  area  was  that 
the  poison  was  conveyed  aerially  direct  from  the  wards  of  the 
hospital. 

As  regards  the  number  of  cases  aggregated  in  a  hospital 
necessary  to  enable  it  to  exert  an  influence  on  the  surrounding 
neighbourhood.  Dr.  Power's  reports  of  1884-5  show  that  this 
influence  was  exerted  when  the  number  of  acute  cases  had  been 
restricted  to  twenty;  whilst  on  one  occasion  he  found  the 
excess  of  small-pox  in  the  neighbourhood  of  the  Fulham  Hospital 
was  quite  remarkable  at  a  time  when  the  total  admissions  to 
hospital  had  not  exceeded  nine,  only  five  of  these  being  cases  in 
an  acute  stage. 

On  the  other  hand,  Dr.  Savill  (Warrington  outbreak,  1892-3) 
and  others  have  considered  that  there  are  so  many  agencies  at 
work  for  the  conveyance  of  infection  by  human  means  (more 
especially  in  the  vicinities  of  the  hospitals),  that  the  hypothesis 
of  aerial  convection  is  unnecessary.  That  a  small-pox  hospital 
in  a  poor  and  crowded  locality  may  be,  and  usually  is,  a  source 
of  infection  to  the  surrounding  neighbourhood  is  not  denied: 
but  the  incomings  and  outgoings  of  the  staff,  the  calls  of  trades- 
men and  friends  of  the  patients,  and  the  bringing  of  the  patients 


432  HYGIENE    AND    PUBLIC    HEALTH 

to  the  hospitals,  are  all  dangers  which  of  necessity  become 
intensified  as  the  centre  is  approached,  and  may  in  themselves 
account  for  this  circumstance. 

One  consideration  which  causes  many  to  doubt  the  correctness 
of  the  aerial  convection  theory  is  the  immunity  from  attack 
constantly  observed  in  the  large  numbers  of  presumably  sus- 
ceptible individuals  living  near  small-pox  hospitals,  and  the 
circumstance  that  in  a  number  of  instances  no  such  special 
incidence  of  attack  has  been  observed.  Dr.  Power's  views, 
then,  are  thought  by  many  to  be  adequately  explained  by  the 
possibilities  of  direct  or  mediate  infection  from  the  hospital. 

The  most  recent  instance  of  apparent  aerial  infection  is  that 
reported  by  Dr.  Thresh  from  Purfleet,  Essex.  This  village  is 
on  the  Essex  shore  of  the  Thames,  almost  opposite  the  Metro- 
politan Small-pox  Hospital  Ships  (which  were  moored  near  the 
Kent  shore),  and  included  within  a  three-quarter  mile  radius 
from  the  ships.  After  the  commencement  of  the  London  out- 
break in  August,  1901,  Purfleet  was  very  exceptionally  invaded 
by  small-pox;  and  it  is  difficult  to  account  for  this  exceptional 
invasion,  as  there  was  little  communication  between  the  ships 
and  the  Essex  shore. 

A  Local  Government  Board  circular  on  "  The  Provision  of 
Isolation  Hospital  Accommodation  by  Local  Authorities  "  has, 
with  a  view  to  lessening  the  risk  of  infection  from  small-pox 
hospitals,  laid  down  the  rule  that  a  local  authority  should  not 
contemplate  the  erection  of  a  small-pox  hospital — first,  on  any 
site  where  it  would  have  within  a  quarter  of  a  mile  of  it  as  a 
centre,  either  a  hospital,  whether  for  infectious  diseases  or  not, 
or  a  workhouse,  or  any  similar  establishment,  or  a  population 
of  150  to  200  persons;  and  secondly,  on  any  site  where  it  would 
have  within  half  a  mile  of  it  as  a  centre,  a  population  of  500  to 
600  persons,  whether  in  one  or  more  institutions,  or  in  dwelling- 
houses.  Cases  in  which  there  is  any  considerable  collection  of 
inhabitants  just  beyond  the  half-mile  zone  should,  says  the 
circular,  "  always  call  for  especial  consideration." 

The  contagion  clings  persistently  to  infected  clothing,  bedding, 
and  furniture,  and  is  often  communicated  by  means  of  these 
infected  articles. 

Like  many  other  specific  infectious  diseases,  small-pox  has  a 
special  seasonal  prevalence  (see  fig.  79)^  From  observations 
covering  a  long  period  of  years,  it  can  be  shown  that  the  average 


COMMUNICABLE   DISEASES 


433 


London  mortality  is  greatest  during  the  first  six  months  of  the 
year,  rising  to  a  maximum  towards  the  end  of  May  and  falUng 


through  June,  until?  it  descends  below  the  mean  line,  where  it 
fluctuates  during  the  last  six  months,  to  again  rise  in  December 
or  January. 

Small-pox  is  a  disease  of  every  climate  and  every  race,  and 


28 


434  HYGIENE   AND    PUBLIC    HEALTH 

attacks  all  ages  and  both  sexes  unprotected  by  a  previous  attack 
or  by  vaccination.  In  this  country,  however,  it  causes  a  some- 
what higher  death-rate  amongst  males  than  amongst  females, 
which  indicates  either  a  greater  susceptibility  to  attack  on  the 
part  of  males,  or  a  greater  chance  of  an  attack  proving  fatal 
in  their  case.  Thus,  the  average  death-rate  for  males  at  all  ages 
in  England  during  the  years  1854-87  was  0-183  per  1,000  living; 
whilst  the  death-rate  for  females  at  all  ages  was  only  0-148  per 
1,000  living.  It  arises  solely  from  the  contagion  of  a  previous 
case,  and  although  its  severity  may  be  intensified  by  uncleanly 
and  overcrowded  houses  and  insanitary  surroundings,  as  is 
the  case  with  all  infectious  diseases,  it  cannot  be  originated  by 
any  such  conditions.  It  is  probable  that  during  epidemic  periods 
small-pox  is  very  frequently  spread  by  the  number  of  mild  and 
not  easily  recognizable  cases  of  the  modified  disease  in  vaccinated 
persons,  and  the  failure  to  distinguish  chicken-pox  from  this 
type.  The  virus  from  such  mild  forms  is  capable  of  imparting 
a  very  virulent  form  to  unvaccinated  persons,  and  the  same 
holds  true  of  nearly  all  infectious  diseases. 

Previous  to  the  discovery  by  Jenner,  towards  the  end  of  the 
eighteenth  century,  of  the  protection  afforded  by  the  inoculation 
of  cow-pox  lymph  against  attacks  of  small-pox,  small-pox  was 
a  disease  from  which  few  escaped.  From  1750  to  1800,  small- 
pox caused  nearly  one-tenth  of  the  total  number  of  deaths  (96 
out  of  every  1,000  deaths  from  all  causes),  and  in  epidemic 
years — 1796,  for  example — -this  fatality  was  occasionally  nearly 
doubled.  So  universal  was  the  disease,  and  so  frightful  its  dis- 
figuring effects  and  the  risk  of  loss  of  sight,  that  the  practice  of 
inoculation,  introduced  originally  from  Constantinople  by  Lady 
Mary  Montagu,  became  very  general  during  the  latter  half  of  the 
eighteenth  century.  The  fatality  of  the  disease  so  imparted  was 
found  to  be  much  less  than  that  of  natural  small-pox,  2  or  3  per 
cent,  of  the  cases  ending  fatally  instead  of  20  or  30  per  cent. ; 
but  the  infection  was  thereby  enormously  multiplied  all  over 
the  country,  and  the  epidemics  became  more  frequent  than  ever. 

Jenner  published  the  result  of  his  researches  in  1798,  and  since 
that  time  vaccination  has  made  steady  progress  through  all  classes 
of  the  population,  with  the  result  of  gradually  diminishing  the 
frequency  of  epidemics,  the  severity  of  the  disease,  its  incidence 
on  the  population,  and  its  death-rate.  In  1838  gratuitous  vacci- 
nation was  provided,  and  in  1854  vaccination  became  compulsory 


COMMUNICABLE   DISEASES 


435 


for  all  infants  above  the  age  of  three  months;  but  it  was  not  until 
1871  that  Boards  of  Guardians  were  obliged  to  appoint  public 
vaccinators  for  their  districts.  ,  From  1838  to  1853  the  annual 
death-rate  from  small-pox  in  England  and  Wales  averaged  042 
per  1,000  persons  living;  but  during  the  past  twenty  years  the 
average  is  below  002  per  1,000.  At  the  same  time  the  proportion 
of  small-pox  deaths  to  deaths  from  all  causes  has  fallen  gradually 
from  nearly  100  per  1,000  (or  ^V)  in  the  eighteenth  century  to  an 
average  of  about  10  per  1,000  (or  yw)  from  the  year  of  com- 
pulsory vaccination  to  the  present  time.  The  average  death- 
rate  from  small-pox  in  the  eighteenth  century  was  probably 
not  less  than  3  or  4  per  1,000.  During  the  ten  years  1891-igoo 
the  average  death-rate  in  England  was  only  0013  per  1,000, 
notwithstanding  the  increased  facilities  for  the  spread  of  the 
disease  resulting  from  the  greater  crowding  on  area  of  the 
population  during  recent  years. 

]\Iean  Annual  Death-rates  from   Small-pox  at  Successive  Life 
Periods  per  Million  living,  at  each  such  Life  Period. 


All 

45  and 

ages. 

0-5- 

S-io. 

10-15. 

15-23- 

25-45- 

upwards. 

I.  Vaccination  op- 

tional(i  847-53) 

305 

1617 

337 

94 

IU9 

66 

22 

IL  Vaccination  ob- 

ligatory,     but 

1 

not    efficiently 

1 

enforced  (i  854- 

i 

71)      ...     . 

^^3 

817 

243 

88 

163 

131 

52      j 

IIL  Vaccination  bet- 

1 

ter  enforced 

i 

by  vaccination 

1 

officers    (1872- 

91)     ...     . 

89 

177 

95 

54 

97 

86 

38 

IV.   1 891-1900      .     . 

13 

29 

10 

3 

8 

17 

10 

Compulsory  vaccination  in  infancy  has  saved  the  lives  of  an 
enormous  number  of  children,  who  formerly  died  of  small-pox, 
whilst  the  death-rate  from  small-pox  at  all  ages  has  of  recent  years 
greatly  diminished.  The  mortahty  from  small-pox  amongst 
infants  under  one  year  of  age  is  largely  due  to  deaths  of  infants 
from  this  disease  before  vaccination  has  been  performed.  After 
the  age  of  fifteen  the  protective  influence  of  the  primary  vacci- 
nation has  to  a  large  extent  disappeared;  and  unprotected 
adults  form  a  larger  proportion  of  the  population  than  in  the 
earlier  periods,  when  an  attack  of  small-pox  in  childhood  was  far 


436  HYGIENE    AND    PUBLIC   HEALTH 

more  common  and,  as  a  rule,  gave  immunity  from  the  disease 
for  the  rest  of  hfe. 

It  was  at  first  thought  that  one  vaccination  afforded  indefinite 
protection  to  the  individual  against  small-pox.  This  is  now 
known  not  to  be  the  case — with  regard  to  infantile  vaccination, 
at  least.  In  the  first  place,  the  efficacy  of  vaccination  depends 
largely  upon  the  efficiency  of  the  operation  and  the  number 
and  character  of  the  resulting  scars.  Secondly,  the  protective 
influence  wears  away  with  the  lapse  of  time,  and  revaccination 
at  or  before  the  age  of  puberty  is  a  measure  the  necessity  of 
which  is  beyond  question.  Calf  lymph,  and  that  from  a  vaccine 
vesicle  of  the  eighth  day  from  a  healthy  infant,  if  used  perfectly 
fresh,  are  probably  capable  of  giving  equally  good  results,  as 
regards  protection. 

The  protective  effects  of  vaccination  have  been  studied  chiefly 
in  relation  to  the  fatality  and  severity  of  the  disease  in  the 
vaccinated  and  unvaccinated.  But  this,  it  must  be  remembered, 
is  only  one  side  of  the  question,  and  the  relative  incidence  of 
the  disease  on  these  two  classes  is  deserving  of  study.  The 
exact  proportion  of  unvaccinated  to  vaccinated  in  the  com- 
munity is  not  definitely  known,  but  taking  it  at  its  highest 
figure,  the  unvaccinated  probably  do  not  form  more  than  lo  per 
cent,  of  the  total  population.  On  the  other  hand,  the  unvacci- 
nated certainly  form  not  less  than  30  per  cent,  of  the  cases 
treated  in  small-pox  hospitals,  and  the  proportion  of  severe  and 
haemorrhagic  cases  is  far  larger  amongst  the  unvaccinated  than 
the  vaccinated. 

The  fatality  of  the  disease  in  the  two  classes  is  illustrated 
in  the  diagram,  founded  on  figures  supplied  by  Dr.  Collie  (for 
the  two  epidemic  years  of  1871  and  1881),  of  cases  treated  in 
London  small-pox  hospitals  (fig.  80).  Under  fifteen  years  of 
age  and  over  fifteen  years  the  mortality  per  cent,  of  cases  in  the 
unvaccinated  is  nearly  identical,  viz.,  37  or  38  per  cent.;  whilst 
under  fifteen  the  influence  of  the  number  and  character  of  the 
scars  in  the  vaccinated  is  seen  to  be  of  not  nearly  so  much 
importance  as  over  fifteen.  The  evanescence  of  the  protective 
influence  of  primary  vaccination  after  the  age  of  fifteen  is  thus 
well  exhibited:  for  whereas  one  or  more  bad  marks  reduce  the 
mortality  to  4  per  cent,  under  fifteen,  over  fifteen  the  mortality 
of  cases  with  one  or  more  bad  marks  is  10  per  cent.  Taking 
nearly  7,000  cases  observed  in  recent  years,  the  Royal  Com. 


COMMUNICABLE    DISEASES 


437 


mission  on  Small-pox  and  Vaccination  found  that  the  small- 
pox fatality  rate  in  persons  with  one  mark  was  6-2  per  cent. ; 
with  two  marks,  5-8  per  cent.;  with  three  marks,  37  per  cent.; 
and  with  four  marks,  22  per  cent. 

Revaccination  at  puberty,  if  properly  performed,  confers  a 
very  high  degree  of  immunity  from  small-pox  for  the  remainder 
of  life;  and  if  by  any  chance  a  revaccinated  person  should 
acquire  small-pox,  the  disease  generally  assumes  its  mildest  type. 
In  Prussia  since  the  year  1874,  when  vaccination  and  revaccina- 
tion became  compulsory,  the  death-rate  from  small-pox  has  been 


Under  i  5  Years. 

30 
25 
20 
15 
10 

5 

0 


Over  i  5  Years 
3S 


BCD 


Fig.  80. — Small-pox  Epidemics,   1871,   1881;    Mortality  Per  Cent,  in 
Fever  Hospitals   (London). 

-  IS    +15 

(3S6)  (174)  A=unvaccinated. 

(222)  (483)  i?  =  one  or  more  bad  marks. 

(76)  (141)  C  =one  good  mark. 

(44)  (151)  D  =  two  good  marks. 

(70)  (100)  E  =  three  good  marks. 


reduced  to  one-tenth  of  its  former  rate,  viz.,  from  0-24  per  1,000 
to  0-02  per  1,000;  and  it  is  stated  that  in  the  Prussian  Army 
there  has  not  been  a  single  death  from  small-pox  from  1874  to 
the  present  time. 

In  Germany,  with  a  population  of  over  50,000,000,  surrounded 
on  three  sides  by  badly  vaccinated  countries,  small-pox  has  been 
almost  stamped  out,  and  during  the  ten  years  1885-95,  79  per 
cent,  of  the  few  cases  which  occurred  were  resident  on  the 
frontiers;  whereas  in  Austria  and  Belgium,  where  vaccination  is 
not  compulsory,  the  death-rates  from  small- pox  are  more  than 
twenty-fold    as   great.     The    great    immunity   which    Germany 


438  HYGIENE    AND   PUBLIC   HEALTH 

enjoys  is  due  to  the  fact  that  in  that  country  vaccination  and 
revaccination  are  compulsory,  and,  as  a  consequence,  in  Berhn, 
with  a  population  of  2,000,000,  12  hospital  beds  reserved  for 
small-pox  have  been  found  for  many  years  to  suffice  for  all 
requirements.  The  compulsory  vaccination  age  is  the  second 
year  of  life,  and  it  is  significant  to  note  that  in  1886-90  more 
than  two-fifths  of  the  few  deaths  that  occurred  from  small-pox 
were  under  two  years  of  age.  Revaccination  is  performed  in 
Germany  at  the  end  of  the  period  of  compulsory  school  attend- 
ance, and  every  recruit  is  re  vaccinated  on  joining  the  army. 
In  France  primary  vaccination  must  be  performed  between  three 
and  twelve  months  of  age,  and  revaccination  between  ten  and 
eleven  years  of  age,  and  again  between  twenty  and  twenty-one. 

Dr.  Barry  found  from  the  facts  of  the  Sheffield  epidemic  of 
1887-8  that  unvaccinated  children  under  ten  years  are  twenty 
times  more  hable  to  attack  than  the  vaccinated,  and  unvaccinated 
persons  over  ten  are  five  times  more  liable ;  and  in  unvaccinated 
children  under  ten  the  attack  is  twenty-two  times  more  likely 
to  be  fatal  than  among  the  vaccinated,  while  in  unvaccinated 
persons  over  ten  the  risk  of  an  attack  proving  fatal  is  eleven 
times  as  great.  Therefore,  during  small-pox  prevalence,  an 
unvaccinated  child  under  ten  is  440  times  more  liable  to  die 
than  a  vaccinated  one,  and  an  unvaccinated  person  over  ten 
is  fifty-five  times  more  Hkely  to  die  than  a  vaccinated  one. 
Moreover,  17-2  per  cent,  of  the  attacks  were  severe  among  those 
vaccinated,  while  among  the  unvaccinated  81  per  cent,  were 
severe;  and  in  children  under  ten  years  9  per  cent,  of  the  attacks 
were  severe  among  those  vaccinated,  and  78  per  cent,  among 
those  unvaccinated. 

In  houses  invaded  by  small-pox,  in  the  course  of  an  outbreak, 
not  nearly  so  many  of  the  vaccinated  inmates  are  attacked  as 
of  the  unvaccinated,  in  proportion  to  their  numbers.  Taking 
children  under  ten  in  invaded  houses,  in  Dewsbury,  10  2  per 
cent,  of  the  vaccinated  were  attacked,  and  50-8  per  cent,  of  the 
imvaccinated;  in  Leicester,  25  per  cent,  of  the  vaccinated,  and 
35  per  cent,  of  the  unvaccinated;  and  in  Gloucester,  8-8  per 
cent,  of  the  vaccinated,  and  46-3  per  cent,  of  the  unvaccinated. 

It  is  the  custom  for  antivaccinators  to  attribute  the  reduction 
in  small-pox  incidence  to  improved  sanitation;  but  improved 
sanitation  will  not  account  for — (i)  The  fact  that  small-pox 
mortality   has   been   transferred   from   childhood   to   the   later 


COMMUNICABLE   DISEASES  439 

periods  of  life  since  vaccination  lias  been  introduced;  whereas 
in  Germany,  where  vaccination  is  not  compulsory  till  the  second 
year  of  age,  over  40  per  cent,  of  all  the  small-pox  mortality  occurs 
under  two  years  of  age.  (2)  The  immunity  enjoyed  by  revacci- 
nated  postmen  and  nurses.  The  rcvaccinated  nurses  at  the 
Leicester  Small-pox  Hospital  escaped,  while  those  who  refused 
revaccination  were  attacked.  (3)  That  the  disease  passes  by 
the  vaccinated  children,  but  attacks  the  unvaccinated  living 
in  the  same  house,  as  in  Dewsbury,  Leicester,   and  Gloucester. 

(4)  The   lessened   fatality   among   the   vaccinated   if   attacked, 

(5)  That  those  with  three  or  four  vaccination  marks  are  less 
liable  to  a  fatal  attack  than  those  with  one  or  two.  (6)  The 
great  immunity  which  Germany  enjoys,  even  as  compared  with 
Great  Britain.  Finally,  the  disease  has  never  been  shown  to 
be  caused,  directly  or  indirectly,  by  any  insanitary  condition. 

The  isolation  of  small-pox  cases  in  hospitals  is  a  useful  auxiliary 
to  vaccination,  but  it  is  not  a  sufficient  substitute  for  it,  owing 
to  the  inevitable  failure  to  secure  isolation,  in  all  cases,  with  the 
necessary  thoroughness  and  promptness.  Such  failure  results 
from  parents  not  observing  the  early  symptoms  of  the  illness,  the 
neglect  to  call  in  a  doctor,  the  difficulties  of  diagnosis,  the  delays 
in  removal,  the  probable  inadequacy  of  the  hospital  accommoda- 
tion during  an  epidemic,  and  the  possible  inefficiency  of  the 
disinfection  of  infected  articles. 

The  operation  of  vaccination,  if  properly  performed  with 
clear  fresh  lymph,  does  not  impart  any  other  disease  but 
vaccinia.  But  among  the  maladies  which  have  been  attributed 
to  vaccination  are:  syphilis,  erysipelas,  diarrhoea,  tabes  mesen- 
terica  and  scrofula,  bronchitis,  cancer,  leprosy,  and  many  forms 
of  skin  disease. 

Vaccino-syphilis  has,  however,  in  the  past  happened  so  rarely 
as  to  constitute  it  a  clinical  curiosity.  With  the  general  intro« 
duction  of  calf  lymph  it  will  disappear  altogether,  as  calves  are  not 
subject  to  syphilis.  Vaccino-syphihs  has  often  been  confounded 
with  a  congenital  syphilis,  latent  until  lighted  up  by  vaccination. 
The  acquired  syphilitic  rash,  however,  appears  at  the  earliest 
from  fifty  to  ninety  days  after  vaccination,  and  in  every  case  a 
chancre  forms  at  the  site  of  vaccination.  The  syphilitic  chancre 
is  limited  to  one  or  two  points  of  inoculation,  inflammation  is 
slight,  loss  of  substance  is  superficial,  and  the  parchment  in- 
duration is  typical  (Fournier).      That  the  increase  in  infantile 


440  HYGIENE    AND    PUBLIC    HEALTH 

syphilis  is  due  to  vaccination,  as  asserted  by  the  anti vaccinators' 
is  disproved  by  the  fact  that  whereas  in  England  and  Wales' 
with  vaccination  generally  enforced,  the  increase  in  the  infant 
mortality  from  syphilis  between  the  two  periods,  1863-7  ^^^ 
1883-7,  ^v^s  247  per  cent.,  in  Leicester,  where  vaccination  has 
been  neglected,  the  increase  was  no  less  than  69  3  per  cent. 

As  to  vaccino-erysipelas,  this  disease  has  doubtless  often  re- 
sulted from  vaccination,  either  directly  from  the  failure  to  take 
due  precautions  as  regards  cleanliness  at  the  time  of  the  opera- 
tion, or,  indirectly,  from  exposure  to  dirt  and  insanitary  condi- 
tions in  the  home  of  the  recently  vaccinated  infant.  The 
frequency  of  occurrence  of  vaccino-erysipelas  is,  however,  greatly 
exaggerated  by  the  antivaccinators.  In  the  two  periods  already 
mentioned  the  infant  mortality  from  erysipelas  in  England  and 
Wales  decreased  by  167  per  cent.,  whilst  m  Leicester,  with 
neglected  vaccination,  there  was  an  increase  of  41-5  per  cent. 
Similarly,  diarrhoea  and  bronchitis  have  increased  among  the 
unvaccinated  infants  of  Leicester  more  than  in  England  and 
Wales  as  a  whole,  a  fact  which  proves  the  fallacy  of  attributing 
any  increase  to  vaccination. 

With  regard  to  cancer,  the  Royal  Commission  on  Vaccination 
concluded: — "  There  is  not  a  shadow  of  evidence  to  connect  the 
increase  with  the  practice  of  vaccination,  whilst  there  is  .  .  . 
evidence  pointing  the  other  way."  The  same  remarks  are  applic- 
able to  the  alleged  spread  of  leprosy  by  vaccination.  There 
is  no  evidence,  moreover,  that  tuberculosis  has  ever  been  in- 
oculated by  vaccination,  and  attempts  to  thus  inoculate  the  skin 
of  guinea-pigs  with  lymph  from  tuberculous  patients  have 
uniformly  failed.  That  the  disease  may  be  transmitted  through 
the  medium  of  animal  (calf)  lymph  is  a  groundless  fear,  which 
has  been  encouraged  by  antivaccinators.  Such  a  case  has  never 
yet  been  reported,  although  animal  vaccine  has  been  in  use 
for  many  years,  more  especially  on  the  Continent. 

Certain  rashes  have  doubtless  been  produced,  and  not  infre- 
quently, by  vaccination.  Even  when  vaccine  quite  pure  and  free 
from  other  virus  is  inoculated,  eruptions  of  urticaria,  erythema, 
lichen,  purpura,  and  later,  as  sequelae  of  vaccination,  eczema, 
psoriasis,  and  pemphigus,  have  been  observed.  When,  however, 
the  vaccine  has  not  been  pure,  impetigo  contagiosa,  syphilis 
(very  rare),  erysipelas,  cellulitis,  pyaemia,  or  local  gangrene  have 
occasionally  resulted  from  the  inoculation  of  the  lymph. 


COMMUNICABLE   DISEASES  44^ 

It  is  the  intention  of  the  Government  to  Hmit  vaccination  and 
revaccination  in  the  future,  so  far  as  is  possible,  to  vaccination 
with  glycerinated  or  chloroformed  calf-lymph.  The  object  is 
to  reduce  the  risks  of  conveying  "  vaccinal  "  diseases,  which 
were  sometimes  incidental  to  "  arm-to- arm  "  vaccination.  The 
glycerine  or  chloroform  serves  to  preserve  the  lymph,  without 
in  any  way  interfering  with  its  activity,  and  it  destroys  extraneous 
organisms  (even,  in  time,  the  Bacillus  tuberculosis).  The  presence 
of  a  little  blood  in  the  lymph  is  quite  harmless,  and  the  danger 
of  imparting  disease  appears  to  be  absolutely  avoided  by  the 
use  of  such  lymph. 

The  calves  used  are  carefully  watched,  their  past  history  is 
enquired  into,  they  are  slaughtered  after  use,  and  a  post-mortem 
examination  is  made,  whilst  in  some  countries  the  calf  is  tested 
with  tuberculin  before  inoculation  with  vaccine  lymph.  These 
precautions  are  taken  notwithstanding  the  great  rarity  of  tuber- 
culosis in  young  bovines.  The  age  of  the  calf,  its  general  health 
and  nutrition,  and  even  the  season  of  the  year,  affect  the  quality 
of  the  lymph  collected. 

In  Paris  the  lymph  is  diluted  with  an  equal  bulk  of  glycerine ; 
in  Brussels  twice  the  bulk  of  glycerine  is  added;  in  England  five 
to  eight  times  its  bulk  of  40  or  50  per  cent,  pure  glycerine  in 
distilled  water  is  added;  and  in  Berhn  a  solution  of  equal  parts 
of  glycerine  and  boiled  water  is  added  to  the  epithelial  pulp 
scraped  from  the  vaccine  vesicles,  in  the  proportion  of  14  parts 
of  the  solution  to  i  of  the  pulp. 

In  the  process  of  chloroforming,  a  mixture  of  chloroform  vapour 
and  air  is  passed  through  the  vaccine  emulsion.  The  vaccine 
so  treated  can  be  issued  for  vaccination  purposes  after  an  interval 
of  seventeen  days,  which  is  a  shorter  period  than  is  required  in 
the  case  of  glycerinated  lymph. 

It  is  probable  that  if  vaccination  is  performed  on  a  person  who 
has  already  contracted  small-pox,  within  forty-eight  hours  of 
the  exposure  to  contagion,  vaccinia  ensues  and  small-pox  is 
avoided.  But  if  performed  at  a  later  date  small  -  pox  is 
contracted,  modified  if  within  three  days,  but  unmodified  if 
later,  with  vaccinia  possibly  running  its  own  course  at  the  same 
time. 

Considerable  evidence  has  now  been  accumulated  in  support 
of  the  view  that  cow-pox  is  human  variola  modified  by  its  occur- 
rence in  the  cow.     Klein  has  shown  that  when  lymph  from  the 


442  HYGIENE    AND    PUBLIC   HEALTH 

vesicles  of  a  human  small-pox  case  is  inoculated  into  a  calf,  very 
little  local  result  is  produced,  but  that  if  material  from  the  local 
lesion  is  taken  on  the  fifth  day,  and  inoculated  into  another 
calf,  and  this  process  is  continued  until  four  calves  have  been 
inoculated,  the  material  from  the  fourth  calf  (four  removes  from 
the  small-pox  patient)  might  with  safety  be  transferred  to  the 
human  subject,  with  the  production  of  typical  vaccinia.  The 
lymph  from  the  vaccine  vesicles,  so  produced  in  the  human 
subject,  caused,  alike  on  inoculation  into  the  bovine  or  the  human 
subject,  typical  vaccinia. 

Whatever  the  original  cause  of  cow-pox  in  the  bovine  species, 
it  seems  certain  that  the  disease  is  now  transmitted  directly 
from  animal  to  animal,  and  that  its  origin  from  human  small- 
pox is  an  event  of  very  rare  occurrence,  if  it  ever  happens. 

Small-pox  may  be  confounded  with  measles  and  scarlet  fever, 
owing  to  scarlatiniform  or  morbilliform  rashes  occasionally 
preceding  the  true  variolous  eruption;  and  the  latter  may  be 
mistaken  for  chicken-pox,  acne,  impetigo,  eczema,  syphilis,  and 
typhus.  A  failure  to  recognize  the  true  nature  of  the  disease  is 
often  responsible  for  subsequent  spread  in  epidemic  form. 

The  chief  preventive  measures  to  be  taken  on  the  occurrence 
of  a  case  of  small-pox  are: — (i)  The  removal  of  the  patient  to 
an  isolation  hospital;  (2)  the  disinfection  of  infected  rooms  and 
clothing;  (3)  the  revaccination  of  the  other  inmates  of  the  house; 

(4)  either  the  quarantining  of  those  contacts  for  fourteen  days 
who  have  had  personal  communication  with  the  patient  during  his 
illness;  or  a  daily  medical  inspection  with  the  object  of  promptly 
isolating   them    on    the    appearance   of   the   initial   symptoms; 

(5)  the  notification  of  schools  attended  by  children  in  the 
house. 

Having  regard  to  the  fact  that  in  the  event  of  an  outbreak  of 
small-pox  the  Sanitary  Authority  has  to  direct  all  the  other 
administrative  measures  taken  to  stamp  out  the  disease,  it  is  an 
anomaly  that  the  important  measure  of  vaccination  and  revac- 
cination should  not  also  be  under  its  direct  control. 

It  is,  moreover,  desirable  that  legislation  should  empower  the 
infliction  of  a  penalty  for  withholding  the  fullest  information,  or 
for  giving  false  information,  when  sanitary  officials  are  en- 
deavouring to  trace  the  origin  of,  or  to  otherwise  deal  with, 
the  infection. 

With    reference   to   the   quarantining  of  contacts  the    Local 


COMMUNICABLE    DISEASES  443 

Government   Board,   in   a  circular  issued  in    1902,   advised  as 
follows  : — 

If,  on  a  dwelling  becoming  invaded  by  small-pox,  the  actual  patients  are 
at  once  removed  to  hospital,  the  dwelling  and  all  articles  in  it  that  have 
been  exposed  to  infection,  including  the  clothes  worn  by  the  other  inmates, 
are  properly  disinfected,  and  the  other  inmates  of  the  house  are  immediately 
revaccinated  or  vaccinated  (as  the  case  may  be),  there  is  no  material 
advantage  to  be  gained  by  keeping  these  other  inmates  at  home.  They  are 
not  likely  to  infect  other  people  unless  they  themselves  develop  small-pox; 
and  all  that  is  required  is  to  keep  such  persons  under  medical  observation 
for  a  fortnight,  and  particularly  to  examine  them  carefully  day  by  day 
towards  the  end  of  the  second  week  from  their  exposure  to  infection,  in 
order  to  ascertain  whether  any  of  them  are  developing  small-pox.  If  none 
of  them  do  so  by  the  beginning  of  the  third  week  from  exposure,  the 
revaccination  (or  vaccination)  to  which  they  were  at  once  submitted  on 
the  occurrence  of  the  first  case  in  the  invaded  house  should  secure  them 
from  attack  by  the  disease. 

The  Board  consider  that  in  ordinary  circumstances  the  course  ot  action 
indicated  above  is  the  correct  one.  Occasions,  however,  may  arise  in  which 
additional  precautions  may  be  necessary;  as,  for  example,  when  laundries 
are  in  question,  or  where  the  business  or  habits  of  the  inmates  of  an  invaded 
house  are  such  as  to  make  it  difficult  for  proper  medical  observation  of  them 
to  be  maintained.  In  exceptional  cases  of  this  kind,  in  which  a  Borough 
Council  are  advised  by  their  Medical  Officer  of  Health  that  in  the  special 
circumstances  it  is  essential  that  the  inmates  should  remain  in  their  own 
houses,  the  Board  would  be  prepared  to  sanction  a  reasonable  expenditure 
in  securing  such  a  result. 

Many  outbreaks  of  small-pox  have  been  traced  to  tramps — 
a  class  of  people  who  are  practically  exempt  from  any  sort 
of  sanitary  supervision.  To  obviate  this  danger,  the  local 
authority  should  be  empowered  to  require  a  medical  examina- 
tion of  all  persons  entering  common  lodging-houses  and  casual 
wards,  and  to  enforce  the  temporary  detention  of  all  small-pox 
"  contacts  "  of  the  vagrant  class. 

The  point  has  been  recently  raised  that  as  small-pox  is  now 
comparatively  a  rare  disease  in  this  country,  and  that  as  modern 
methods  of  pubhc  health  administration  are  generally  effective 
in  preventing  any  wide-spread  diffusion  from  isolated  cases, 
it  is  no  longer  necessary  to  secure  compulsory  vaccination  in 
infancy.  It  is  also  said  that  the  presence  in  a  population  of 
large  numbers  of  persons  who  are  partially  protected  only  by 
a  previous  vaccination,  leads  to  the  occurrence  of  numerous 
cases  of  modified  small-pox,  which  are  difficult  to  diagnose,  with 
the  result  that  cases  of  true  small-pox  are  missed,  and  there  is 
a  danger  to  the  public  from  this  very  fact.  It  is  argued  that 
if  all  cases  of  small-pox  occurring  in  a  population  were  un- 


444  HYGIENE  AND  PUBLIC  HEALTH 

modified,  owing  to  the  unprotected  condition  of  the  people, 
small-pox  would  be  easy  to  diagnose,  and  but  few  cases  would 
ever  be  missed.  It  is  suggested  that  vaccination  need  only  be 
resorted  to  for  contacts,  who  had  been  exposed  to  infection, 
or  be  made  available  for  the  general  population,  when  the 
measures  of  control  had  failed,  and  an  epidemic  was  threatening. 
Those  who  still  favour  compulsory  vaccination  in  infancy 
point  out  that  it  is  not  only  the  cases  of  small-pox  modified  by 
previous  vaccination  that  cause  errors  in  diagnosis,  but  also  the 
mild  cases  of  the  unmodified  disease,  which  would  be  as  numerous 
as  heretofore;  and  that  there  is,  in  consequence,  no  guarantee 
that  errors  in  diagnosis  would  be  very  materially  reduced  if  the 
population  was  entirely  unprotected  by  vaccination.  More- 
over, if  compulsory  vaccination  was  abolished  now,  it  would  be 
many  years  before  those  who  have  been  at  some  time  vaccinated 
died  out ;  and  in  any  case  large  numbers  of  people  who  believe 
in  vaccination  will  still  have  their  children  vaccinated  soon  after 
birth.  On  general  grounds  there  appears  to  be  reason  to  believe 
that  small-pox  is  less  Ukely  to  become  epidemic  in  a  partially 
protected  community  than  in  an  entirely  unprotected  one;  and 
that  it  would  be  very  unwise  in  the  present  state  of  our  know- 
ledge to  discard  a  prophylactic  measure,  which  may  be  in  many 
respects  defective,  but  is  still  better  than  no  prophylaxis  at  all. 

Scarlet  Fever. 

This  is  a  specific  infectious  disease  like  small-pox,  its  propaga- 
tion being  dependent  upon  a  specific  contagium  derived  from  a 
previous  case  of  the  disease.  The  incubation  period  varies  from 
a  few  hours  to  eight  days,  and  is  usually  from  twenty-four  to 
seventy-two  hours.  Infection  is  given  off  in  the  throat  secre- 
tions and  from  the  skin  of  the  patient  during  the  whole  period  of 
illness,  but  the  acute  stage  of  the  fever,  when  the  sore  throat  and 
rash  are  most  highly  developed,  is  doubtless  the  most  infectious, 
and  not  the  desquamative  stage,  as  once  generally  supposed.  The 
contagion  clings  with  great  pertinacity  to  the  clothes,  bedding, 
and  furniture  of  the  sick-room,  but  is  not  capable  of  diffusion 
and  dissemination  through  the  air  without  loss  of  virulence, 
like  the  small-pox  contagium  appears  to  be.  Schools  play  an 
important  part  in  disseminating  infection,  and  many  milk-bonie 
outbreaks  of  this  disease  have  been  recorded. 

The  usual  duration  of  infectiveness  in  scarlet  fever  is  from  six 


COMMUNICABLE   DISEASES  445 

to  eight  weeks,  lasting  throughout  convalescence,  and  possibly 
prolonged  by  the  occurrence  of  nasal  or  oral  discharges,  etc. 
In  large  towns  scarlet  fever  epidemics  tend  to  recur  every  few 
years,  as  a  fresh  series  of  susceptible  children  accumulates  in  the 
community. 

Scarlet  fever  is  more  especially  a  disease  of  childhood,  the 
incidence  being  greatest  at  five  and  six  years  of  age.  The 
influence  of  age  and  sex  upon  the  incidence  and  fatality  of  the 
disease  may  be  thus  summarized : — 

The  mortality  from  scarlet  fever  is  greatest  in  the  fourth  year 
of  life,  and  after  this  diminishes  with  age,  at  first  slowly  and 
afterwards  rapidly,  owing  to  the  diminishing  risk  in  successive 
age  periods  of  an  attack,  should  it  occur,  proving  fatal.  The 
liability  to  attack  is  small  in  the  first  year  of  life,  increases  to 
a  maximum  in  the  fourth  or  fifth  year,  and  then  becomes  rapidly 
smaller  and  smaller  with  the  advance  of  years.  The  female  sex 
throughout  life  is  more  liable  to  scarlet  fever  than  the  male  sex; 
but  the  attacks  in  males,  though  fewer,  are  more  likely  to  ter- 
minate fatally. 

The  proportion  of  fatal  cases  to  attacks  of  scarlet  fever  cannot 
be  accurately  stated,  owing  to  the  large  number  of  unrecognized 
cases  of  very  mild  type,  often  without  skin  eruption,  and  with 
very  little  desquamation.  The  case  mortality  (proportion  of 
deaths  to  attacks)  is  not  greater  than  from  i  to  2  per  cent. 
The  very  mild  and  unrecognized  cases  are,  doubtless,  the  most 
frequent  sources  of  dissemination  of  infection,  and  the  fact  of 
their  being  true  scarlet  fever  cannot  be  doubted.  The  mortality 
of  well-marked  cases,  such  as  those  admitted  into  the  Metro- 
politan fever  hospitals,  is  now  about  2  per  cent.,  whilst  the 
mortality  of  notified  cases  in  London  is  16  per  cent.  (191 1). 

For  the  five  years  igoi-5,  the  death-rate  from  scarlet  fever  per 
1,000  living  at  all  ages  in  England  and  Wales  was  0-13.  In  igio 
it  was  only  0-07.  During  the  ten  years  1871-80,  the  average 
death-rate  in  England  and  Wales  from  scarlet  fever  was  07  per 
1,000  living  at  all  ages. 

The  lower  mortality  from  scarlet  fever  of  recent  years  is  due, 
not  to  a  lesser  prevalence  of  the  disease,  but  to  a  milder  type. 
The  proportion  of  deaths  to  attacks  is  now  only  about  a  half  of 
what  prevailed  thirty  years  ago. 

Scarlet  fever  is  a  disease  from  which  very  many  people  alto- 
gether escape.     The  importance  of  saving  young  children  from 


446  HYGIENE    AND    PUBLIC    HEALTH 

attacks  of  scarlet  fever  has  been  well  expressed  by  Dr.  White- 
legge:— 

"  In  shielding  a  child  against  infection  during  the  first  few 
years  of  life  there  is  a  double  gain;  every  year  of  escape  from 
scarlet  fever  renders  him  less  and  less  susceptible,  until  finally 
he  becomes  almost  insusceptible;  and,  secondly,  even  if  he  should 
ultimately  take  the  disease,  every  year  that  the  attack  is  deferred 
reduces  the  danger  to  life  which  it  brings.  In  other  words 
attacks  of  scarlet  fever  become  both  less  severe  and  less  frequent 
with  every  year  of  age  after  the  fifth.  Up  to  the  fifth  year  the 
liability  is  less  (than  in  the  fifth  year),  but  the  risk  of  life  in  case 
of  attack  is  very  great." 

The  same  reasoning  applies  with  almost  equal  force  to  measles, 
whooping  cough,  and  the  other  infectious  complaints  of  child- 
hood. 

Overcrowding  and  insanitary  conditions  in  houses  tend  to 
aggravate  the  severity  of  scarlet  fever  attacks,  and  to  aid  in  their 
dissemination,  but  can  have  no  influence  per  sc  in  originating  an 
outbreak. 

Scarlet  fever  is  most  prevalent  and  most  fatal  in  the  months 
of  October  and  November.  Two  curves  may  be  formed,  one 
expressing  the  deaths  as  percentages  of  the  average  mortality 
throughout  the  year  (fig.  79),  the  other  expressing  the  number 
of  cases  as  percentages  of  the  average  of  cases  throughout  the 
year.  These  curves  correspond  very  closely,  but  Dr.  Whitelegge 
has  noted  that  the  mortality  curve  rises  less  and  falls  less  above 
and  below  the  mean  than  the  case  curve,  which  would  imply  that 
when  most  prevalent  scarlet  fever  is  least  fatal,  and  vice  versa. 
There  is  a  strong  probability  in  favour  of  this  view,  as  the  number 
of  mild  cases  is  usually  greatest  when  scarlet  fever  is  most 
prevalent. 

It  sometimes  happens  that  a  patient  discharged  from  hospital, 
apparently  free  from  infection,  is  the  means  of  communicating 
the  disease  to  another  member  of  the  family  on  his  return  home. 
These  "  return  cases,"  which,  however,  in  most  large  communities 
form  less  than  3  per  cent,  of  the  total  cases  treated  in  hospital, 
have  been  explained  in  many  ways.  Doubtless  they  are  some- 
times examples  of  mere  coincidence;  at  others  they  may  result 
from:  (i)  the  non-disinfection  of  articles  of  clothing,  books,  or 
toys,  which  have  been  used  by  the  patient  prior  to  removal  to 
hospital,  and   produced   again   on   the   patient's  return   home; 


COMMUNICABLE   DISEASES  447 

(2)  carelessness  on  the  part  of  hospital  officials  in  prematurely 
discharging  patients  with  unhealthy  throats,  nose  and  ear  dis- 
charges, etc.,  or  in  not  sufficiently  bathing  the  patients  and 
shampoohig  the  head  prior  to  cUscharge;  (3)  the  reappearance  of 
desquamation  (?),  or  infectious  discharges  after  dismissal  of  the 
patient  from  hospital  in  an  apparently  healthy  condition ;  (4)  the 
conveyance  of  the  infection  in  the  lungs  of  recently  discharged 
patients  (?). 

The  entire  prevention  of  such  "  return  cases,"  even  by  the 
exercise  of  every  possible  care,  seems  impossible  in  practice; 
but  their  number  would  doubtless  be  reduced  if  parents  could 
and  would  observe  the  precaution  of  keeping  the  child  apart 
from  other  children  for  at  least  one  week  after  returning  home 
from  hospital.  The  provision  of  special  convalescent  wards,  of 
smaller  wards  involving  less  aggregation  of  the  patients,  and  the 
greater  development  of  bacteriological  assistance,  are  further 
measures  that  are  recommended. 

The  value  of  the  hospital  isolation  of  scarlet  fever  has  been 
called  in  question,  as  those  towns  where  the  largest  proportion  of 
cases  are  thus  isolated  cannot  be  shown,  statistically,  to  have 
suffered  less  from  scarlet  fever  than  others  where  little  or  no 
such  isolation  has  been  provided.  This  is  largely  due  to  the 
fact  that  the  value  of  the  hospital  isolation  of  this  disease  has 
been  discounted  by  the  frequent  failure  to  recognize  cases  of 
infection  in  a  sufficiently  early  stage — -more  especially  during  the 
recent  years  of  attenuated  virulence  of  the  disease.  But  hos- 
pitals are  only  one  of  the  factors  which  determine  the  prevalence 
of  infectious  diseases,  and  the  other  factors  concerned  may  con- 
ceivably favour  those  towns  where  hospital  isolation  has  been 
comparatively  Uttle  practised;  besides,  we  have  no  means  of 
knowing  what  would  have  happened  in  those  towns  where  a 
large  proportion  of  cases  are  isolated,  if  no  hospital  isolation 
provision  had  existed.  Moreover,  the  different  wave  lengths  of 
epidemics,  the  variable  intervals  between  local  epidemics,  and 
the  different  proportions  of  those  comprised  within  the  sus- 
ceptible age  periods  in  the  towns  compared,  may  make  the 
comparison  a  misleading  one. 

Certainly  scarlet  fever  is  now  a  very  mild  disease,  and  a  large 
amount  of  money  is  spent  upon  its  isolation  to  the  possible 
prejudice  of  other  far  more  fatal  diseases;  and  these  facts  warrant 
some  discrimination  in  the  selection  of  the  cases  which  should 


448  HYGIENE    AND    PUBLIC    HEALTH 

be  admitted  to  hospital — the  cases  selected  being  limited  to 
those  who  cannot  possibly  be  isolated  at  home  owing  to  special 
circumstances,  including  interference  with  the  wage-earning  or 
educational  needs  of  the  other  members  of  the  household.  It  is 
only  reasonable  to  maintain  that  hospital  isolation  of  the  disease 
must  have  done  something  to  reduce  the  number  of  those  who 
would  otherwise  have  been  attacked,  and  that  skilled  hospital 
treatment  must  have  been  beneficial  to  the  sufferers;  but  there 
is  little  to  be  said  for  the  indiscriminate  isolation  practised  in 
London  and  elsewhere.  In  conclusion  it  must  be  borne  in  mind 
that  the  experience  of  the  past  shows  that  the  infection  of  scarlet 
fever  has  exhibited  secular  periods  of  attenuation  and  renewed 
virulence;  and  the  disease  may  possibly  in  a  few  years  again 
assume  the  severer  type,  which  demands  an  extensive  provision 
of  hospital  isolation. 

Measles. 

A  specific  infectious  fever,  with  an  incubation  period  generally 
of  nine  to  twelve  days,  but  which  may  be  as  short  as  four  days 
and  as  long  as  fourteen.  The  contagion  is  given  off  from  the 
secretions  of  the  nose,  throat,  lungs,  and  possibly  from  the  skin 
of  the  patient  during  the  whole  period  of  illness.  The  catarrhal 
stage  preceding  eruption  is  especially  infectious,  and  at  this  stage 
it  is  impossible  to  diagnose  the  complaint  with  certainty.  It 
is  for  this  reason  that  epidemics  of  measles  are  so  difficult  to 
control.  The  infection  is  not  widely  diffusible  in  the  air,  but 
chngs  to  clothes  and  garments. 

Measles  is  a  disease  of  infancy  and  early  childhood,  and  is 
very  fatal  to  young  children,  frequently  owing  to  pulmonary 
complications  and  sequelae.  Adults  unprotected  by  a  previous 
attack  are  also  susceptible,  but  the  disease  is  so  universal  in 
this  country  that  few  children  escape  from  it.  The  mortality 
from  measles  is  greatest  under  three  years  of  age;  the  highest 
death-rate  is  reached  in  the  second  year  of  hfe;  after  five  years  of 
age  the  mortality  is  enormously  diminished.  Over  90  per  cent. 
of  the  total  deaths  are  among  children  under  five.  During  the 
five  years  igoi-5,  the  death-rate  at  all  ages  in  England  and  Wales 
from  measles  was  033  per  1,000  living  at  all  ages;  and  in  1910, 
it  was  0-23.  In  the  ten  years  1871-80,  the  average  death-rate 
in  England  from  measles  was  0-38  per  1,000  living  at  all  ages; 
and  in  the  decennium  1861-70  it  was  0-44.  Both  sexes  are  equally 
liable  to  attack,  and  the  case  mortality  is  about  the  same  for 


COMMUNICABLE  DISEASES  449 

bath.  In  this  disease  the  case  mortaUty  is  greatly  affected  by 
overcrowding  and  insanitary  conditions  generaUy.  In  the  over- 
crowded houses  of  the  poor,  amongst  badly  nurtured  children y 
the  proportion  of  deaths  to  attacks  may  be  as  much  as  20  or 
30  per  cent.,  and  is,  no  doubt,  intensified  by  the  neglect  of  the 
parents  to  provide  suitable  warmth  and  nourislniient  for  the 
sufferers  from  a  disease  which  they  think  of  little  moment.  In 
healthy  houses,  well-nourished  children  almost  invariably  make 
a  good  recovery.  The  cases  admitted  to  the  Metropolitan 
Asylums  Board  Hospitals  in  1911  showed  a  case  mortality  of 
13-9  per  cent. 

Measles  is  most  prevalent  and  most  fatal  in  the  winter  months 
of  November,  December,  and  January;  but  it  also  tends  to  become 
somewhat  intensified  in  the  late  spring  (May  and  June)  (fig.  79) . 

Measles  epidemics  tend  to  recur  in  large  towns  about  every  two 
or  three  years,  with  the  accumulation  of  a  batch  of  susceptible 
children ;  and  since  the  disease  is  pre-eminently  fatal  in  the  first, 
second,  and  third  years  of  life,  it  follows  that  if  it  can  be  so  far 
discouraged  by  preventive  measures  as  to  acquire  epidemicity 
only  every  fourth  year,  a  large  number  of  children  will  have 
passed  the  age  at  which  the  disease  is  most  fatal,  and  many  lives 
will  be  saved. 

Some  people  ad .  ocate  the  compulsory  notification  of  measles, 
and  the  arguments  that  have  been  adduced  in  favour  of  this 
measure  are  as  follows  : — 

It  is  claimed  that  compulsory  notification  furnishes  early 
information  of  the  first  cases,  and  that  notification  is  the  best 
means  of  obtaining  this  information.  This  information  would 
enable  the  following  measures  to  be  carried  out :  (i)  the  visiting 
of  parents  and  guardians,  and  advising  as  to  isolation  and  removal 
to  hospital  (where  hospital  provision  exists) ;  (2)  the  control  of 
school  attendances ;  and  (3)  the  prompt  detection  (to  be  followed 
by  closure)  of  schools  or  school  classes  which  are  acting  as  foci 
for  the  dissemination  of  infection. 

It  has  also  been  asserted  that  the  notification  of  measles,  and 
the  measures  resulting  therefrom,  would  cause  the  public  to  regard 
the  disease  with  more  seriousness,  and  that  it  would  encourage 
amongst  the  poor  a  more  general  medical  attendance  upon  the 
sufferers. 

Those  who  do  not  favour  the  compulsory  notification  of  the 

disease  maintain  that,  on  account  of  the  exceedingly  infectious 

29 


450  HYGIENE   AND   PUBLIC   HEALTH 

pre-eruptive  stage  of  measles,  the  notification  certificate  would 
arrive  too  late  to  be  of  much  value  in  the  adoption  of  the  measures 
necessary  to  protect  others  in  the  infected  household.  In  most 
cases  four  days  elapse  (during  which  the  infection  is  at  its  highest) 
before  the  characteristic  rash  makes  its  appearance,  and  another 
day  at  least  would  follow  before  the  notification  is  received  and 
acted  upon.  Prior  to  the  rash  the  disease  cannot  be  diagnosed, 
and  all  those  who  are  susceptible  have  probably  been  fully 
exposed  to  the  infection.  This  is  the  intrinsic  difficulty  which 
has  to  be  faced  in  measures  deahng  with  this  complaint.  Further, 
there  is  a  great  tendency  among  the  poor  to  regard  the  disease  as 
inevitable  and  trivial,  and  in  consequence  they  do  not  recognize 
the  desirability  of  isolation,  nor  do  they  consult  a  medical  man 
in  a  large  percentage  of  cases,  unless  grave  symptoms  supervene. 
In  country  districts  the  majority  of  the  cases  are  not  medically 
attended.  Obviously,  then,  those  cases  which,  occurring  in 
small  houses  often  crowded  with  other  children,  are  the  most 
potent  for  harm,  would  not  be  notified;  and  the  notification  of 
cases  among  the  better  classes,  who  have  already  called  in  a 
medical  man  and  received  the  benefit  of  his  advice,  would  form 
the  bulk  of  the  notifications  received. 

Efficient  home  isolation  of  infant  sufferers  from  measles  in 
the  dwellings  of  the  poorer  classes  is  generally  impracticable; 
and  without  the  means  of  offering  hospital  isolation,  the  com- 
pulsory notification  of  measles  would  be  premature.  But  even 
if  such  hospital  provision  were  made — and  it  would  have  to  be 
on  a  very  large  scale  to  deal  with  a  fair  proportion  of  the  cases 
occurring  in  an  epidemic — there  would  still  be  much  difficulty 
found  in  inducing  the  parents  to  consent  to  the  removal  from 
home  of  children  of  such  tender  years  as  those  who  form  the  bulk 
of  the  sufferers  from  measles. 

Certainl}/,  if  notification  is  to  prove  of  service,  every  possible 
use  must  be  made  of  the  information  it  provides.  Every  infected 
household  must  be  promptly  visited;  the  source  of  infection 
traced;  the  existence  of  unnotified  cases  discovered,  if  possible, 
from  the  clues  afforded  by  the  notified  cases;  schools,  libraries, 
etc.,  must  be  communicated  with;  premises  must  be  disinfected; 
and  suitable  isolation  at  home  insisted  upon  (where  possible). 
Now,  all  this  would  entail  a  large  staff,  which  could  scarcely  be 
appointed  temporarily  with  advantage;  and  if,  therefore,  notifica- 
tion proved  a  failure,  it  would  be  a  very  costly  one. 


COMMUNICABLE  DISEASES  451 

During  past  years  a  few  (under  i  per  cent.)  of  the  sanitary 
autliorities  in  England  and  Wales  have  included  measles  in  the 
list  of  notifiable  diseases;  and  in  the  majority  of  cases  the  Medical 
Officers  of  Health  either  acknowledge  that  they  have  reaped  no 
advantage,  or  they  express  their  doubts  as  to  the  utility  of  the 
measure. 

It  is  both  interesting  and  significant  to  note  that,  up  to  the 
commencement  of  the  year  1899,  the  Infectious  Diseases  Notifi- 
cation Act  had  been  extended  to  measles  in  no  cases,  to  rotheln 
in  seven,  to  whooping  cough  in  twenty-six,  and  to  chicken-pox 
in  eight  (on  account  of  the  frequency  with  which  it  is  confused 
with  modified  small-pox).  But  in  over  forty  of  these  cases  the 
sanitary  authorities  have  subsequently  revoked  the  addition  of 
measles,  in  one  that  of  rotheln,  in  seven  that  of  whooping  cough, 
and  in  four  that  of  chicken-pox,  while  in  one  case  the  Act  was 
extended  to  measles  only  for  a  limited  period,  which  has  now 
expired. 

It  may  be  useful  to  bring  measles  under  the  Notification  Act 
in  rural  districts  and  in  small  isolated  communities,  if  in  tliese 
cases  every  advantage  is  taken  of  the  information  thus  obtained 
to  detect  unnotified  cases,  and  the  means  of  hospital  isolation 
are  provided;  but  in  larger  communities,  especially  when  not 
adopted  in  neighbouring  districts,  the  measure  is  not  to  be 
recommended. 

What  has  to  be  faced  is  a  largely  preventable  mortality  due 
to  ignorance — a  mortality  which  is  very  high  among  the  poor, 
and  very  low  among  the  better  classes;  and  the  most  successful 
scheme  for  reducing  measles  mortality  appears  to  be  one  which 
will  take  advantage  of  all  the  means  which  elementary  schools 
offer  of  (a)  educating  the  future  parents  to  take  a  more  serious 
view  of  the  disease,  and  to  treat  children  affected  on  proper  lines, 
and  of  (b)  gaining  early  information,  and  checking  the  spread  of 
infection. 

The  greatest  checks  to  the  spread  of  the  disease  would  be  the 
exclusion  from  school  of  the  younger  children  from  infected 
houses,  the  sending  home  of  suspicious  scholars,  the  visitation 
of  absentees,  the  prompt  notification  to  the  sanitary  authority 
of  infected  households  by  school  attendance  ofiicers,  and  the 
occasional  prompt  closure  of  schools  (infants'  departments) 
during  epidemic  periods. 

Occasionally  measles  is  responsible  for  considerable  loss  of 


452  HYGIENE   AND    PUBLIC   HEALTH 

school  attendance.  To  reduce  this  to  a  minimum  it  is  now 
advocated  that  a  "  measles  history  "  of  the  school  children 
attending  each  class  should  be  kept ;  and  when  a  child  is  suspected 
to  be  suffering,  and  the  record  shows  that  he  has  not  had  the 
complaint,  and  is  therefore  susceptible,  he  should  be  sent  home. 
If,  when  the  disease  is  rife,  the  class  contains  a  large  proportion 
of  such  susceptibles,  it  should  be  promptly  closed. 

Dr.  Thomas  found  (i)  that  in  London,  except  in  the  better 
class  districts,  75  per  cent,  of  the  scholars  above  five  years  of  age 
are  protected  by  a  previous  attack,  and  therefore  at  present  the 
disease  can  spread  but  little  in  classes  of  scholars  above  that 
age;  (2)  that  a  class  of  over  30  per  cent,  of  susceptibles  is  one 
in  which  the  disease  tends  to  spread;  and  (3)  that,  if  children 
under  five  were  excluded,  school  closure  for  measles  would  be 
unnecessary  in  London.  When  school  closure  is  resorted  to, 
it  must  take  place  before  the  "  first  crop  "  of  cases  occurs,  if  any 
useful  purpose  is  to  be  effected. 

It  is  highly  desirable  that  measles  should  be  definitely  brought 
within  the  scope  of  the  expression  "  infectious  diseases,"  as  used 
in  the  Pubhc  Health  Acts  of  1875  and  1891  (London),  in  so  far 
as  relates  to  wilful  exposure  of  sufferers. 

Rotheln,  Rubella,  or  German  Measles. — This  is  a  specific  infec- 
tious fever,  propagated  by  a  specific  contagium ;  and  not  a  hj^brid 
between  measles  and  scarlet  fever,  from  neither  of  which  diseases 
is  it  protective.  It  has  a  usual  incubation  period  of  fourteen  to 
eighteen  days,  but  this  may  vary  from  one  to  three  weeks, 
and  the  patient  is  infectious  during  the  whole  course  of  illness 
(seven  to  fourteen  days).  It  is  not  a  disease  of  common  occur- 
rence, and  the  illness  produced  is  almost  invariably  very  mild. 
Children  and  young  adults  are  most  susceptible. 

Whooping  Cough. 

This  is  a  specific  infectious  disease,  the  infection  being  given 
off  in  the  secretions  from  the  lungs.  The  specific  organism  has 
not  yet  been  determined,  although  there  is  some  support  of  the 
claim  that  Bordet's  bacillus  is  specific.  It  is  probably  not 
carried  far  in  the  air,  but  clings  pertinaciously  to  articles  of 
clothing.  The  period  of  incubation  may  last  from  one  to  three 
weeks,  and  the  period  of  infectiveness  is  usually  not  less  than 
six  weeks  from  the  onset  of  cough,  and  may  be  longer. 

Infants  and  young  children   are  especially  susceptible,   and 


COMMUNICABLE    DISEASES  453 

comparatively  few  escape  attack.  The  younger  the  child,  the 
greater  is  the  likelihood  of  the  attack  proving  fatal;  40  per  cent, 
of  the  mortality  from  whooping  cough  occurs  in  the  first  year, 
30  per  cent,  in  the  second,  15  per  cent,  in  the  third,  and  6  per  cent, 
in  the  fourtli.  Girls  suffer  more  from  severe  attacks  which  end 
fatally  than  boys,  and  their  liability  to  contract  the  disease  is 
also  probably  greater.  In  the  first  two  years  of  life  the  pro- 
portion of  deaths  to  attacks  cannot  be  less  than  10  per  cent., 
and  is  probably  higher.  After  the  third  year  this  proportion 
is  not  more  than  2  per  cent.  The  case  mortality  of  cases  ad- 
mitted to  the  Metropolitan  Asylums  Board  Hospitals  in  191 1 
was  13-2  per  cent.  Adults  seldom  suffer,  as  they  are  so  generally 
protected  by  an  attack  in  childhood;  but  if  unprotected  they 
are  equally  liable  with  children. 

Whooping  cough  is  now  the  most  fatal  of  all  the  infectious 
complaints  of  childhood  under  the  age  of  five  years;  the  deaths 
being  due  in  most  cases  to  pulmonary  complications  (broncho- 
pneumonia). For  the  year  1910,  the  death-rate  was  2-i  per 
1,000  under  five  years  of  age  (measles  being  1-9).  Between  1871 
and  1880  the  death-rate  for  all  ages  averaged  0-5  per  1,000;  and 
in  1910  it  was  0-25  per  1,000. 

Whooping  cough  occurs  in  regularly  recurring  epidemics  every 
few  years,  but  it  has  an  exceptional  prevalence  and  fatality  in 
the  spring.  The  seasonal  curve  attains  its  maximum  late  in 
March  or  early  in  April,  and  from  that  point  rapidly  declines 
{see  fig.  79). 

Outbreaks  of  whooping  cough  and  measles  frequently  occur 
at  the  same  time,  and  the  preventive  measures  in  both  diseases 
are  similar. 

Varicella. 

Varicella,  or  chicken-pox,  is  often  mistaken  for  mild  or 
modified  attacks  of  small-pox;  but  the  two  diseases  are  quite 
distinct.  It  is  a  mild  disease,  but  rarely  fatal  when  uncom- 
plicated with  other  disease,  and  children  are  mainly  attacked. 
The  incubation  period  varies  from  thirteen  to  nineteen  days, 
and  is  commonly  about  fourteen  days.  The  infection  of  varicella 
is  very  considerable  from  the  first,  and  may  remain  active  for 
some  time  in  fomites.  The  patient  should  be  isolated  until  the 
last  scab  has  fallen  off. 


454  HYGIENE   AND    PUBLIC   HEALTH 

Mumps. 

Often  in  cold  and  wet  weather  an  epidemic  of  this  disease 
breaks  out,  the  infection  spreading  with  great  rapidity,  but 
giving  rise  to  Httle,  if  any,  mortahty.  Outbreaks  are  sometimes 
associated  with  an  epidemic  of  measles.  Nothing  is  known  of 
the  etiology  of  the  disease,  but  it  is  probably  microbic  in  origin, 
the  organism  entering  the  gland  from  the  mouth  by  way  of 
Stenson's  duct.  One  attack  generally  confers  immunity  from 
others.  The  disease  attacks  chiefly  the  early  age-periods  of  life, 
and  the  incubation  period  is  generally  three  weeks,  but  may 
vary  from  fourteen  to  twenty-five  days.  The  swellings  of  the 
parotid  and  submaxillary  glands,  which  are  the  most  prominent 
symptoms,  generally  remain  for  about  a  fortnight. 

Occasionally  epidemics  occur  among  young  adults;  and  then 
serious  complications  are  by  no  means  uncommon,  and  deaf- 
ness, etc.,  may  result. 

Typhus. 

A  specific  contagious  disease,  but  almost  invariably  found 
to  be  associated  with  conditions  of  filth,  privation  and  over- 
crowding in  large  towns  amongst  poor  working-class  populations. 
The  usual  period  of  incubation  is  about  one  to  two  weeks. 
The  infection  appears  to  exist  in  the  exhalations  from  the  lungs 
and  skin,  and  to  be  transmitted  through  the  air  from  the  sick 
to  the  healthy;  but  it  is  rapidly  destroyed  by  dilution  with 
fresh  air,  and  does  not  cling  to  articles  of  clothing,  so  that  in  a 
well-ventilated  house  typhus  rarely  spreads  from  the  original 
case.  The  disease  can  be  transmitted  experimentally  from 
man  to  man  and  from  man  to  monkeys,  and  a  frequent  agent 
of  transmission  appears  to  be  the  body-louse.  The  infective 
virus  is  an  ultra-microscopic,  filtrable,  organism ;  and  the  blood- 
serum  of  convalescents  can  confer  a  high  degree  of  immunity 
upon  others.  The  female  sex  and  the  age-period  of  fifteen  to 
thirty  years  appear  to  be  the  most  susceptible. 

The  disease  is  liable  to  be  mistaken  for  enteric  fever,  pneu- 
monia, meningitis,  and  even  scarlet  fever  and  measles.  Ill- 
defined  illness  often  precedes  attacks,  and  these  are  characterized 
by  their  sudden  onset  and  the  late  appearance  of  the  rash.  The 
symptoms  of  the  disease  are  often  mild  and  atypical  in  children. 

Being  so  closely  associated  with  overcrowding,  typhus  increases 


COMMUNICABLE    DISEASES  455 

in  intensity  during  cold  weather,  when  there  is  an  inducement 
for  many  people  to  huddle  together  to  keep  warm.  In  some 
of  our  large  towns,  epidemics  have  recurred  in  certain  poverty- 
stricken  quarters  with  considerable  regularity,  as  fresh  susceptible 
individuals  accumulate. 

The  mortality  from  typhus  has  undergone  an  enormous 
diminution  in  this  country  during  the  last  twenty  years.  Before 
1869,  typhus,  enteric  fever,  and  simple  continued  fever  were 
included  in  the  Registrar-General's  returns  under  the  generic 
heading  of  "  Fever  ";  but  since  that  date  mortality  returns  of 
these  three  diseases  have  been  presented  separately.  In  1869 
the  death-rate  from  typhus  in  England  was  0-193  per  1,000 
living  at  all  ages;  but  for  the  ten  years  ending  1910  the  average 
annual  rate  has  been  only  00008. 

Simple  Continued  Fever. 

This  is,  probably,  in  a  large  majority  of  cases,  a  convenient 
term  for  the  registration  of  deaths  from  undiagnosed  and  obscure 
cases  of  fever,  such  as  may  occur  in  typhus,  general  tuberculosis, 
septicaemia,  pneumonia,  and  intermittent  fever.  Dr.  Longstaff 
is  of  opinion  that  only  a  very  small  proportion  of  these  deaths, 
if  any,  are  due  to  enteric  fever.  Simple  continued  fever  as  a 
cause  of  death  exhibits  a  decrease  in  the  last  twenty  years  closely 
analogous  to  that  of  typhus  (in  1867  the  death-rate  was  0-24  per 
1,000;  in  the  ten  years  ending  1910  the  average  death-rate  was 
only  0-0015).  This  decrease  is,  no  doubt,  largely  due  to  greater 
precision  in  diagnosis,  but  may  to  a  certain  extent  be  due  to  the 
diminishing  prevalence  of  a  definite  disease. 

Diphtheria. 
The  etiology  of  this  disease  is  still  to  a  certain  extent  veiled  in 
obscurity.  Whilst  on  the  one  hand  it  cannot  be  doubted  that 
the  contagion  is  transmitted  from  the  sick  to  the  healthy,  on  the 
other  hand  diphtheria  outbreaks  in  rural  districts  at  times  appear 
to  originate  independently  of  the  infection  of  a  pre-existing  case. 
But  probably  the  diphtheria  contagion  has  the  power,  under 
certain  conditions,  of  lying  latent  for  long  periods  of  time,  with 
the  capacity  of  renewing  its  virulence  under  special  circumstances ; 
and,  as  in  the  case  of  enteric  fever,  mild  and  unrecognized  forms 
of  the  disease  and  "  chronic  carriers  "  may  account  for  much 
obscurity  of  origin. 


456  HYGIENE    AND    PUBLIC   HEALTH 

In  many  instances  of  such  occurrences  the  explanation  may 
be  that  the  organism  of  diphtheria, the  Klebs-I^oeffler  bacilhis, 
is  sometimes  present  in  a  non-virulent  form  in  the  mouths  of 
healthy  persons;  and  if  a  slight  sore  throat  or  tonsillitis  occurs 
in  such  a  person,  then  the  bacilli  may  become  virulent,  and 
give  rise  to  true  diphtheria. 

A  bacillus,  known  as  the  pseudo-diphtheria  bacillus  (Hoffmann), 
has  been  described  by  many  observers  in  the  throats  of  apparently 
healthy  children,  as  well  as  in  those  of  patients  convalescent  from 
diphtheria.  This  pseudo-diphtheria  bacillus  is  morphologically 
and  culturally  aUied  to  the  Klebs-Loeffler  bacillus,  but  is  usually 
non-pathogenic  to  animals.  The  relation  between  the  two 
organisms  has  not  yet  been  conclusively  shown.  Most  authorities 
agree  that  Hoffmann's  bacillus  does  not  necessitate  the  preven- 
tive measures  undertaken  for  coping  against  diphtheria. 

The  diphtheritic  contagion  is  given  off  from  the  body  in  the 
secretions  from  the  mouth,  nose,  and  throat;  and,  although 
probably  not  far  diffusible  in  the  air,  clings  with  great  pertinacity^ 
to  infected  articles  of  clothing  and  bedding. 

As  is  the  case  with  some  other  infectious  maladies,  there  appears 
to  be  in  certain  individuals  a  pecuhar  hereditary  or  family 
susceptibility  to  attacks  of  diphtheria. 

Season  has  a  marked  influence  on  the  manifestation,  and, 
above  all,  on  the  mortality  from  diphtheria.  Epidemic  preva- 
lences of  the  disease  commonly  commence  in  September,  reach 
their  highest  point  during  October  and  November,  and  then 
subside  slowly  during  the  following  two  months — the  smallest 
amount  of  mortality  being  witnessed  from  May  to  July.  There 
is  some  excess  of  diphtheria  mortality  in  females  as  compared 
with  males.  It  is  probably  due,  at  all  periods  of  life,  to  greater 
exposure  of  females  to  infection  in  nursing  (Thornc  Thorne). 
The  incubation  period  is  usually  under  four  days'  duration, 
rarely,  if  ever,  less  than  two  or  more  than  seven  days. 

Diphtheria  occurs  endemically  in  certain  localities,  localized 
epidemic  extensions  taking  place  from  time  to  time.  It  has  been 
a  matter  of  observation  that  certain  districts,  in  which  the 
surface  soil  is  cold  and  humid,  and  where  damp  houses  and 
privy  and  drainage  nuisances  abound,  or  where  the  aspect 
involves  much  exposure  to  cold  and  wet  winds,  suffer  from 
an  exceptional  incidence.  The  broad  geological  features  of  a 
district — the  permeability  or  otherwise  of  the  surface  strata — 


COMMUNICABLE   DISEASES  457 

have  not,  as  such,  any  observed  influence  on  the  development 
and  diffusion  of  the  disease;  but  such  topographical  relations 
as  facilitate  the  retention  of  moisture  and  organic  refuse  in  the 
surface  soil,  or  involve  bleakness  of  site  or  exposure  to  cold  and 
wet  winds,  appear  to  be  of  importance. 

According  to  Newsholme  diphtheria  tends  to  become  widely 
epidemic  in  years  of  deficient  rainfall,  the  epidemic  wave  becom- 
ing most  marked  when  three  or  more  years  of  deficient  rainfall 
follow  each  other. 

Until  lately  diphtheria  was  regarded  as  being  to  a  far  greater 
extent  a  rural  than  an  urban  disease,  but  during  the  last  thirty 
years  diphtheria  mortality  has  progressively  increased  very 
greatly  in  London  and  some  other  large  cities.  Thus,  in  1881  in 
London  the  death-rate  from  diphtheria  was  017  per  1,000,  the 
average  of  the  ten  years  1871-80  being  012  per  1,000.  The 
average  of  the  decennium  1881-90,  however,  was  0-26  per  1,000; 
and  of  the  decennium  1891-1900  0-50  per  1,000.  Since  1899 
there  has,  however,  in  London,  been  a  steady  decline  in  diphtheria 
mortality,  the  death-rate  for  1912  being  only  o-io  per  1,000. 
The  same  progressive  increase  and  subsequent  decrease  has  been 
witnessed  in  some  of  the  other  large  cities  and  towns. 

The  incidence  of  the  disease  is  most  marked  in  children  between 
the  ages  of  two  and  twelve  years,  and  subsequently  decreases 
with  every  year  of  advancing  age.  As  a  rule,  the  younger  the 
child,  the  greater  the  chance  of  an  attack  proving  fatal.  The 
average  mortality  of  cases  notified  in  London  (average  of  18904)- 
was  23-8  per  cent.,  and  is  now  87  per  cent,  (average  of  1905-11), 
antitoxin  having  been  in  regular  use  since  the  end  of  the  year  1894. 
The  case  mortality  in  the  Metropolitan  Asylums  Board  hospitals 
was,  in  the  pre-antitoxin  days,  30-3  per  cent,  (average  of  1888-94), 
and  is  now  under  9  per  cent.,  the  case  mortality  among  those 
treated  with  antitoxin  on  the  first  day  of  the  disease  being  only 
about  3  per  cent. 

School  attendance  is  now  acknowledged  to  be  a  very  potent 
factor  in  the  spread  of  diphtheria,  as  in  scarlet  fever  and  measles. 
Infection  is  spread  by  the  attendance  at  school  of  mild  or  un- 
recognized cases,  and  this  is  especially  likely  to  occur  in  the  public 
elementary  schools,  where  the  class-rooms  are  often  overcrowded 
and  badly  ventilated,  and  the  children  are  brought  into  very  close 
contact  at  the  most  susceptible  age-periods.  Sir  Shirley  Murphy 
has  shown  that  in  London  the  increased  incidence  of  diphtheria 


458  HYGIENE    AND    PUBLIC  HEALTH 

among  children  from  three  to  ten  years  of  age  (school  age)  firsr 
became  conspicuous  in  the  year  1871 — -the  year,  that  is,  in  which 
the  Elementary  Education  Act  first  became  operative ;  that  there 
is  a  marked  decline  in  incidence  during  the  holidays,  and  a  sub- 
sequent rise  with  the  reopening  of  the  schools  (due  allowance 
being  made  for  the  incubation  period  and  for  some  delay  in 
notification).  Although  during  the  summer  holidays  there  is 
also  a  decline  in  incidence  among  persons  over  ten  years  of  age, 
it  is  never  so  great  as  the  decHne  among  children  of  the  school  age 
(three  to  fourteen). 

Prevalences  of  recognized  diphtheria  are  very  commonly 
associated  in  their  beginnings,  during  their  continuance,  and 
after  their  apparent  cessation,  with  a  large  amount  of  ill-defined 
throat  illness.  Vincent's  angina  is  a  disease  allied  to  diphtheria, 
which  spreads  from  direct  or  indirect  contact.  While  the 
patient's  symptoms  in  some  cases  simulate  those  of  diphtheria, 
they  more  commonly  take  the  form  of  deep  ulcerations  on  the 
tonsils,  palate,  etc.  The  disease  is  most  frequent  amongst 
children  from  eight  to  ten  years  of  age.  Diphtheria  epidemics 
are  occasionally  inextricably  mixed  up  with  outbreaks  of  scarlet 
fever  and  measles.  There  is  no  reason  to  believe  that  diphtheria 
is  in  any  way  interchangeable  with  scarlet  fever  or  measles,  in 
the  sense  that  the  infection  of  the  one  disease  may  produce  the 
other;  but  it  would  seem  that  the  morbid  condition  of  the  throat 
left  after  scarlet  fever  or  measles  predisposes  the  sufferer  to  become 
receptive  of  the  diphtheria  contagion,  which  may  at  the  same 
time  be  present.  Faulty  sanitary  surroundings  (drainage  and 
filth  nuisances)  tend  to  the  production  of  diphtheria  in  the  same 
way,  namely,  by  engendering  a  morbid  condition  of  the  tonsils 
favourable  to  the  growth  of  the  diphtheria  contagion  if  implanted 
thereon. 

The  virus  of  diphtheria  attenuated  as  to  its  virulence  by 
exposure  to  atmospheric  conditions  is,  no  doubt,  at  times  widely 
distributed  among  populous  communities.  The  attenuated 
bacilli  very  readily  regain  their  virulence  when  they  become 
implanted  on  human  fauces  weakened  by  the  attacks  of  other 
organisms,  especially  streptococci,  and  the  organisms  associated 
with  measles,  scarlet  fever,  and  rotheln,  as  well  as  of  those  occa- 
sionally present  in  drain  and  sewer  emanations  (drain  throat). 

Patients  convalescing  from  scarlet  fever  are  not  infrequently 
attacked  with  diphtheria  ("  post-scarlatinal  diphtheria  "),   the 


COMMUNICABLE    DISEASES  459 

infection  of  which  is  probably  introduced  into  the  scarlet  fever 
wards  by  an  unrecognized  case  of  diphtheria.  The  prevention 
of  post-scarlatinal  diphtheria  is  a  matter  of  great  difficulty.  A 
bacteriological  examination  of  the  throats  of  all  cases  on  ad- 
mission would  prevent  the  introduction  into  the  fever  wards  of 
cases  of  diphtheria  nmning  concurrently  with  scarlet  fever,  but 
would  not  necessarily  lead  to  the  isolation  of  patients  in  the 
incubation  stage  of  diphtheria. 

An  affection  of  the  throat,  in  many  respects  similar  to  human 
diphtheria,  has  been  noticed  as  occurring  in  pigeons,  fowls,  and 
other  birds,  during  periods  of  epidemic  prevalence  of  this  disease. 
According  to  Klein,  a  very  similar  disease  can  be  produced  in 
cats  by  subcutaneous  inoculation  of  cultures  of  the  Bacillus 
diphtherias,  giving  rise  at  first  to  a  tumour  at  the  seat  of  inocula- 
tion, subsequently  followed  by  broncho-pneumonia  and  kidney 
degeneration.  But  the  bacillus  is  only  recoverable  from  the 
tumour,  and  is  not  found  in  the  blood  or  affected  organs,  pointing 
to  the  visceral  disease  being  a  result,  as  in  man,  of  the  action  of  a 
chemical  poison — an  albumose  (toxin) — produced  by  the  bacillus 
at  the  seat  of  inoculation  and  absorbed  from  thence  into  the 
system.  The  disease  called  diphtheria  in  pigeons,  calves,  and 
other  animals  is  due  to  a  different  organism,  and  appears  not  to  be 
communicable  to  man ;  but  Cobbett  has  recorded  a  case  of  natural 
diphtheria  in  a  pony,  from  which  a  child  contracted  the  disease ; 
and  the  diphtheria  bacillus  has  been  isolated  by  Dr.  Tew  from 
the  apparently  healthy  throat  of  a  cat. 

There  is  abundant  evidence  to  show  that  diphtheria  has  often 
been  conveyed  through  the  medium  of  milk,  and  this  infectivity 
of  the  milk  has  been  ascribed  on  some  occasions  to  some  morbid 
condition  of  the  cow  or  cows.  Klein  has  shown  that  cows  and 
calves,  when  subcutaneously  inoculated  with  cultures  of  the 
Bacillus  diphthericB,  develop  a  disease  similar  to  that  observed  in 
cats,  and  usually  proving  fatal  in  the  course  of  two  or  three  weeks, 
the  chief  post-mortem  signs  being  intense  broncho-pneumonia  and 
necrotic  patches  in  the  liver. 

There  is  Httle  or  no  evidence  pointing  to  the  spread  of  the 
disease  by  drinking  contaminated  water.  Klein  has  stated 
that  the  Bacillus  diphtheria  is  killed  when  kept  for  a  few 
days  in  pure  water,  on  account  of  its  not  finding  sufficient 
nutriment. 

The  specific  bacillus  may  persist  in  the  mouth  for  a  considerable 


460  HYGIENE    AND    PUBLIC   HEALTH 

time  after  the  false  membrane  has  disappeared.  Dr.  Hermann 
Biggs  (New  York  Health  Department)  has  subjected  405  cases 
of  true  diphtheria  to  repeated  bacteriological  examinations  during 
the  course  of  the  disease,  and  during  convalescence.  In  245 
cases  (60-5  per  cent.)  the  Klebs-Loeffler  bacillus  disappeared 
within  three  days  of  the  complete  separation  of  the  false  mem- 
brane; in  103  cases  (25-4  per  cent.)  the  bacilH  persisted  for  seven 
days;  in  34  cases  (8-4  per  cent.)  for  twelve  days;  in  16  cases 
(4  per  cent.)  for  fifteen  days;  in  4  cases  (i  per  cent.)  for  three 
weeks;  and  in  3  cases  (075  per  cent.)  for  five  weeks,  after  the  time 
when  the  exudation  had  completelydisappeared  from  the  upper 
air-passages.-"-  In  many  of  these  cases  the  patients  were  appar- 
ently well  many  days  before  the  infectious  agent  had  disappeared 
from  the  throat.  Such  results  as  the  above  are  suggestive  of  a 
method  of  dissemination  of  the  disease  by  the  mixing  of  con- 
valescents with  healthy  people,  whilst  their  throat  secretions 
still  contain  specific  bacilH.  It  is  never  safe  to  allow  recovered 
patients  to  mix  with  healthy  people  until  at  least  fourteen  days 
have  elapsed  since  the  disappearance  of  all  membrane.  During 
the  whole  of  this  time  the  mouth  and  throat  should  be  repeatedly 
washed  with  disinfectant  lotions;  and  as  the  bacilh  are  frequently 
present  in  the  nasal  discharges,  an  antiseptic  nasal  douche  should 
also  be  used,  especially  if  much  discharge  from  the  nasal  cavities 
was  present  during  the  acute  stage  of  the  disease. 

Outside  the  body  the  diphtheritic  virus  may  possibly  retain 
its  active  properties  for  long  periods  (many  months),  when 
protected  from  light  and  air  currents.  The  action  of  light  and 
air  and  alternating  moisture  and  dryness  destroy  the  virus 
with  considerable  rapidity.  The  bacilli  can  resist  a  dry  heat  of 
98°  C.  for  one  hour,  but  a  moist  temperature  of  58°  C,  acting 
for  ten  minutes,  is  sufficient  to  kill  them,  so  that  boiling  water  or 
disinfection  in  a  steam  chamber  is  always  efficacious  in  destro5dng 
their  vitality. 

1  Sternberg  in  the  1901  edition  of  his  book  quotes  the  following:  "  Park 
and  Beebe  (1894)  in  an  extended  research,  n-iade  for  the  purpose  of  deter- 
mining the  persistence  of  the  diphtheria  bacillus  in  the  throats  of  convales- 
cent.s  (2,566  cultures  made)  found  that,  in  304  out  of  605  consecutive  cases, 
the  bacillus  disappeared  within  three  daj's  after  the  disappearance  of  the 
exudate  (that  is,  in  50'25  per  cent.);  in  176  cases  (:;9'i  per  cent.)  it  per- 
sisted for  seven  days;  in  64  cases  (io-6  per  cent.)  for  twelve  days;  in  36 
cases  (5-9  per  cent.)  for  fifteen  days;  in  12  cases  (2  per  cent.)  for  three 
weeks;  in  4  cases  (o-66  per  cent.)  for  four  weeks;  and  in  2  cases  (0*33  per 
cent.)  for  nine  weeks." 


COMMUNICABLE    DISEASES  461 

Klein  has  shown  experimentally  that  the  virulence  of  B.  diph- 
thericB  can  be  increased  by  placing  it  under  symbiotic  condi- 
tions with  Streptococcus  pyogenes ;  that  is  to  say,  it  may  be 
inferred  from  his  experiments  that  a  mixed  infection  of  these 
organisms  is  liable  to  produce  an  especially  virulent  type  of 
diphtheria. 

It  is  probable  that  the  Klebs-Loeffler  bacillus  may  be  much 
more  widely  distributed  in  the  throat  secretions  of  children  than 
at  one  time  was  considered  possible.  In  large  towns,  when 
diphtheria  was  endemic,  it  would  appear  from  recent  statistics 
that  from  5  to  10  per  cent,  of  the  children  of  the  working  classes 
have  the  bacillus  in  their  throats;  and  in  the  majority  of  these 
cases  there  is  no  evidence  of  any  unhealthy  condition  of  the 
fauces.  These  "  carrier  cases  "  are  of  importance  when  an  out- 
break of  diphtheria  occurs  in  a  school.  The  examination  of  the 
throats  of  all  the  children  and  of  the  nasal  discharges  of  those 
with  "  running  noses,"  may  reveal  in  some  the  presence  of  the 
specific  bacillus.  The  isolation  of  such  children  should  prove 
effective  in  limiting  the  spread  of  the  disease. 

During  the  prevalence  of  the  disease  at  schools  a  prompt 
bacteriological  examination  of  suspects  often  prevents  a  needless 
loss  of  school  attendance.  In  the  London  County  Council's 
Schools  it  has  been  found  safe  to  ignore  the  presence  of  the 
pseudo- diphtheria  bacillus  among  scholars;  but,  when  this 
organism  is  found  during  the  prevalence  of  diphtheria  in  viru- 
lent form,  it  is  wise  to  isolate  those  scholars  who  are  harbour- 
ing it. 

The  presence  of  nasal  diphtheria  must  not  be  overlooked,  as 
the  nasal  passages  have  been  found  to  be  more  commonly 
affected  than  was  at  one  time  suspected. 

An  antitoxin  serum  has  been  introduced  through  the  obser- 
vations of  Behring,  Kitasato,  and  others,  which  not  only  has 
the  power  of  conferring  immunity  upon  animals,  but  also  of 
arresting  the  disease  after  it  has  commenced  in  the  human 
subject.  The  serum  is  obtained  as  follows: — The  virulent 
Klebs-Loeffler  bacillus  is  grown  in  broth  for  seven  to  twelve  days 
at  35°  C,  when  a  maximum  quantity  of  toxin  will  be  furnished 
in  the  liquid  by  the  metabolism  of  the  bacilh.  The  culture 
liquid  is  then  filtered  through  a  porcelain  filter,  to  arrest  all 
microbes,  and  the  clear  liquid  resulting  is  injected  subcutaneously 
into  a  horse.     Gradually,  by  repeated  injections  of  this  toxin 


462  HYGIENE    AND   PUBLIC    HEALTH 

over  a  period  of  two  or  three  months,  the  horse  is  brought 
into  a  condition  in  which  its  serum  possesses  very  high  antitoxic 
properties.  The  animal  is  then  bled,  and  the  serum  obtained 
from  the  drawn  blood  is  mixed  with  a  little  weak  antiseptic, 
usually  0-2  per  cent,  carbolic  acid,  filtered  through  a  porcelain 
filter,   and  after  standardization,   is  stored  ready  for  use   {see 

P-  425)- 

That  the  lessened  case  mortality  from  diphtheria  which  has 

resulted  from  the  use  of  antitoxin  is  not  attributable  to  any 
natural  attenuation  of  the  virus,  or  to  a  change  in  the  conditions 
of  environment,  is  proved  from  the  fact  that  in  parts  of  Germany 
and  elsewhere  on  the  Continent,  whilst  the  local  incidence  of  the 
disease  has  remained  unchanged  among  people  in  the  same  com- 
munity and  influenced  by  similar  sanitary  environments,  there 
is  a  reduction  in  the  case  mortality  only  among  those  who  have 
been  treated  with  antitoxin. 

In  order  to  facihtate  an  early  application  of  the  remedy, 
some  local  authorities  keep  a  stock  of  antitoxin  at  their  public 
offices,  and  supply  it  to  practitioners  at  cost  price,  or  gratuitously 
in  the  case  of  poor  patients.  The  provision  is  a  useful  one,  for 
experience  has  shown  the  high  importance  of  an  early  applica- 
tion of  a  large  initial  dose,  ranging  from  6,000  to  8,000  units, 
according  to  the  gravity  of  the  symptoms. 

Diphtheria  antitoxin  also  possesses  valuable  prophylactic 
properties,  and  may  be  used  with  advantage  in  doses  of  at 
least  1,000  units  for  the  protection  of  children  who  are  or  have 
been  exposed  to  the  risks  of  infection.  Regard,  however,  must 
be  had  to  the  possible  production  of  anaphylaxis  on  the  injection 
of  a  second  dose  [see  p.  425). 

Enteric  Fever. 

Typhoid  or  enteric  fever  is  a  specific  disease  dependent  for 
its  propagation  upon  a  specific  virus — the  Bacillus  typhosus.  It 
is  not  always  possible  to  establish  the  dependence  of  an  outbreak 
on  a  pre-existing  case;  but  it  is  not  necessary  for  this  reason  to 
assume  that  the  disease  can  originate  independently — from 
organic  filth  apart  from  the  infection  of  a  previous  case — seeing 
that  the  contagion  may  possibly  survive  in  polluted  soil  for  a 
certain  period.  Besides  this,  enteric  fever  is  sometimes  a  mild 
disease  and  unrecognized  even  by  the  patient  himself,  who  goes 
about  his  ordinary  avocations  unaware  that  he  may  be  spreading 


COMMUNICABLE    DISEASES  463 

contagion  broadcast;  and  the  proof  now  forthcoming  as  to  the 
existence  of  "  chronic  carriers  "  is  of  especial  importance  in  this 
connection. 

The  period  of  incubation  is  usually  a  long  one,  from  ten  to 
fourteen  days.  The  limits  of  its  maximum  duration  are  not 
accurately  known,  but  in  rare  cases  it  may  be  prolonged  to 
twenty-one  days,  or  even  to  twenty-three. 

Post  mortem  the  B.  typhosus  is  found  in  the  gall-bladder,  cither 
in  the  bile,  in  the  walls  of  the  gall-bladder,  or  in  both  situations. 
The  bacillus  can  be  isolated  from  the  blood  up  to  the  tenth  day  of 
the  disease,  that  is  to  say,  previous  to  the  formation  of  aggluti- 
nins in  the  blood  in  appreciable  quantity.  In  severe  cases  and 
in  relapses,  where  agglutinins  undergo  a  temporary  decrease,  the 
B.  typhosus  may  again  be  found  in  the  blood.  When  the  bacillus 
disappears  from  the  blood,  it  is  deposited  in  the  adenoid  struc- 
tures— the  spleen,  Peyer's  patches  in  the  intestines,  and  the 
mesenteric  glands.  Frequently  the  bacillus  can  be  isolated  from 
the  faeces  during  the  incubation  period,  and  in  the  early  days  of 
illness,  with  difficulty  during  the  height  of  an  attack,  but  in  a 
large  number  of  cases  during  convalescence.  The  bacillus  is  not 
usually  found  in  the  urine  until  the  end  of  the  second  week  of 
illness  (30  per  cent,  of  cases),  but  it  is  then  found  well  on  into 
convalescence. 

Infection  is  transmissible  {a)  by  those  who  are  actually  suffer- 
ing from  a  recognizable  attack,  typhoid  bacilli  being  especially 
numerous  in  the  stools  during  the  third  and  fourth  weeks  of  the 
illness;  {b)  by  those  who  are  suffering  from  an  "  ambulatory" 
type  of  the  disease — the  type  that  is  mild,  obscure,  or  unrecog- 
nizable clinically;  (c)  by  those  who  are  "  contacts  " — i.e.,  those 
who  have  been  infected,  and  who  for  a  time  pass  Bacillus  typhosus 
in  their  excreta,  but  are  apparently  not  in  any  way  affected  in 
health  thereby;  {d)  by  those  who  are  convalescent  from  the 
disease,  but  whose  urine  contains  the  specific  bacilli,  often  in 
pure  culture;  and  {e)  by  those  probably  very  exceptional  cases 
(about  3  per  cent,  of  the  total)  known  as  "  chronic  carrier  " 
cases,  in  which  an  attack  of  enteric  fever  (mostly  in  women, 
about  75  per  cent,  of  these  cases  being  females)  is  succeeded 
by  an  indefinite  period  of  latent  infectivity  lasting  sometimes 
for  many  years,  and  due  apparently  to  the  discharge  from  time 
to  time  of  virulent  typhoid  bacilli  in  the  faeces  for  certain  periods, 
such  periods  alternating  with  others  when  the  discharges  are 


464  HYGIENE   AND    PUBLIC   HEALTH 

free  from  infective  organisms.  Tiie  habitat  of  the  typhoid 
bacilli  in  the  body  in  many  of  these  cases  appears  to  be  the  gall- 
bladder; and  Dr.  Davies  of  Bristol  has  noted  that  in  the  cases 
investigated  by  him  the  months  of  May  and  June  were  those  in 
which  the  bowel  discharges  of  the  "  chronic  carrier  "  resumed 
infectivity.  Carrier  cases  who  are  engaged  in  the  constant 
handhng  of  food  (such  as  cooks  and  dairy  employes)  have  in 
several  recorded  instances  been  responsible  for  an  outbreak  of 
enteric  fever. 

Special  mention  deserves  to  be  made  of  the  now  famous 
Strassburg  case,  described  by  Kayser  in  1906.  It  was  observed 
that  almost  every  new  employe  in  a  bakery,  kept  by  a  woman 
who  had  suffered  from  typhoid  fever  ten  years  previously, 
became  seriously  ill,  with  intestinal  symptoms  resembhng  those 
of  typhoid  fever.  At  length  the  faeces  of  the  woman  were 
examined,  and  were  found  to  contain  the  specific  bacilli  in  large 
numbers. 

It  is  important  to  realize  that  in  enteric  fever  the  urine  in  the 
later  stages  of  the  illness  and  in  convalescence  may  be  more 
potent  for  mischief  than  the  faeces,  as  in  a  certain  proportion  of 
cases  of  this  disease,  which,  according  to  the  recorded  observa- 
tions, may  amount  to  some  20  or  30  per  cent,  of  the  total,  the 
urine  contains  enormous  numbers  of  Bacilli  typhosi. 

Inasmuch  as  the  soihng  of  body-  and  bed-hnen  and  of  water- 
closet  seats  and  chamber  utensils  is  much  more  readily  effected 
by  the  urine  than  by  the  faeces,  it  is  easy  to  understand  how  the 
hands  of  healthy  persons  may  become  infected  by  the  handling 
of  such  objects;  and,  in  consequence,  how  easy  would  be  the 
transmission  of  infection  in  this  manner,  whilst  the  source  of  the 
mischief  would  in  many  instances  be  quite  unrecognized. 

B.  typhosus  may  remain  alive  for  long  periods  in  pure  cultures, 
or  in  urine  or  faeces,  which  contain  no  other  organisms.  The 
presence,  however,  of  B.  coli,  streptococci,  and  other  organisms  is 
markedly  antagonistic  to  the  life  of  B.  typhosus.  The  larger  the 
proportional  numbers  of  such  organisms,  the  more  quickly  does 
B.  typhosus  disappear.  Inasmuch  as  the  multiphcation  of 
B.  coli,  etc.,  depends  largely  on  temperature  (37-5°  C.  being  the 
optimum  for  B.  coli),  the  higher  the  air  temperature,  the  sooner 
B.  typhosus  disappears.  Thus,  in  England  it  has  been  ascer- 
tained that  the  fasces  and  urine  of  typhoid  carriers  may  contain 
B.  typhosus  up  to  twenty-two  days  from  passing  out  of  the  body. 


COMMUNICABLE   DISEASES  465 

whilst  in  India  about  five  days  appears  to  be  the  Hmit.  The 
fingers  of  a  urinary  carrier  were  found  one  hour  after  passing 
urine  to  be  infective,  but  the  fingers  of  a  faecal  carrier  gave  nega- 
tive results.  Ordinary  washing  with  soap  and  water  and  drying 
the  hands  with  a  clean  towel  removes  all  trace  of  B.  typhosus 
from  the  infected  hands. 

B.  typhosus  grows  freely  in  sterilized  milk,  and  may  persist  in 
it  for  an  indefinite  period,  but  in  unboiled  milk  the  B.  coli,  which 
are  always  present,  outgrow  it,  and  B.  typhosus  disappears  within 
three  days.  B.  typhosus  will  multiply  for  twenty-four  hours  in 
soup,  but  dies  out  in  two  or  three  days  if  the  soup  has  not  been 
sterilized. 

Female  chronic  carriers  are  about  five  times  as  numerous  as 
male,  and  females  also  suffer  from  gall-stones  about  five  times 
as  much  as  men  in  the  later  years  of  life.  B.  typhosus  has  the 
power  to  precipitate  cholesterin  from  the  bile,  and  so  produce 
gall-stones,  and  the  bacilli  have  been  found  in  the  interior  of 
gall-stones.  It  seems  probable  that  chronic  carriers  are  due  to 
focal  deposits  of  B.  typhosus  in  the  walls  of  the  gall-bladder,  or 
in  the  pelvis  and  tubules  of  the  kidneys.  These  focal  deposits 
are  probably  determined  by  pre-existing  lesions  at  these  sites, 
which  are  more  common  in  middle  life  than  in  youth,  and  more 
common  (gall-bladder)  in  women  than  in  men,  thus  accounting 
for  the  fact  that  the  female  sex  and  middle  life  exhibit  a  pre- 
ponderance of  chronic  carriers. 

Intermittent  periods  (without  any  discharge  of  B.  typhosus) 
are  much  less  frequently  found  in  the  case  of  urinary  carriers 
than  in  the  case  of  fsecal  carriers.  Chronic  fgecal  carriers  may 
excrete  large  numbers  of  B.  typhosus,  and  yet  the  blood  may  give 
a  practically  negative  Widal  reaction.  Urinary  carriers,  as  a 
rule,  give  positive  reactions  to  the  Widal  test,  and  always  in  higher 
dilutions  than  faecal  carriers. 

Sour  milk  treatment  (lactic  acid  bacilli,  or  B.  Bulgancus)i 
urotropin  and  salol,  for  the  disinfection  of  the  urine  and  the  faeces, 
and  the  application  of  the  Rontgen  rays,  have  all  been  tried  to 
cure  the  chronic  carrier  condition,  but  without  any  considerable 
measure  of  success.  Autogenous  anti-typhoid  vaccines  are  of 
some  value  in  certain  cases  which  have  not  passed  into  the  very 
chronic  stage;  but  in  the  chronic  cases,  with  definite  infective 
foci  shut  off  from  the  general  circulation  by  reason  of  inflam- 
matory processes,  the  result  of  local  irritation  (gall-stones,  gravel, 

30 


466  HYGIENE    AND    PUBLIC   HEALTH 

and  small  abscesses  in  pelvis  of  kidney),  no  measures  at  present 
known  seem  to  be  of  much  utility. 

A  disease  so  closely  simulating  enteric  fever  as  to  be  clinically 
indistinguishable  from  it  is  ascribed  to  a  micro-organism,  or 
rather  to  a  class  of  micro-organisms,  which  have  been  named 
Bacilli  paratyphosi.  The  latter  can  be  distinguished  culturally 
from  the  true  B.  typhosus,  and  have,  in  fact,  cultural  character- 
istics which  seem  to  place  them  generically  between  the  true 
B.  typhosus  and  the  B.  coU  communis,  the  whole  group  of  colon 
organisms  presenting  certain  common  features  which  seem  to 
indicate  a  family  relationship.  The  disease  due  to  paratyphoid 
organisms  is  only,  perhaps,  occasionally  seen  in  Europe  and 
temperate  countries,  and  appears  to  be  even  less  frequent  in 
India,  but  in  South  Africa  it  is  relatively  more  often  met  with. 
Thus,  in  the  Report  of  the  Army  Medical  Department  for  1907  it 
it  stated  that  in  India,  out  of  a  very  large  number  of  examina- 
tions of  blood,  faeces,  and  urine  from  typhoid  cases  made  at  the 
Central  Research  Institute,  in  only  six  were  paratyphoid  bacilli 
found.  Of  these,  four  were  B.  paratyphosus  "  A  "  (Brion-Kayer), 
and  two  were  B.  paratyphosus  "  B  "  (Schotmiiller).  This  pro- 
portion differs  from  what  has  been  found  in  Europe,  where  the 
paratyphoid  organisn  is  far  more  common;  but  it  tends  to 
indicate  that  the  great  majority  of  typhoid  infections  in  British 
troops  in  India  are  due  to  the  B.  typhosus. 

In  South  Africa,  on  the  other  hand,  amongst  the  British  troops 
stationed  there  in  1907,  it  would  appear  that  about  20  per  cent, 
of  the  typhoid  cases  might  be  due  to  organisms  of  the  typhoid 
colon  group  (paratyphoid,  colon  bacillus,  and  unclassified  forms) 
other  than  the  true  B.  typhosus.  It  is  possibly  due  to  the  presence 
of  a  relatively  large  number  of  these  atypical  and  mild  cases  that 
the  proportion  of  deaths  to  attacks  of  enteric  fever  in  South 
Africa  is  comparatively  low. 

According  to  Forster  and  Kayser,  the  serum  of  those  who 
merely  harbour  the  B.  typhosus  as  a  saprophyte  in  the  intestine, 
without  having  actually  suffered  from  typhoid  ("  acute  carriers  "), 
has  generally  no  agglutinative  power.  To  add  to  our  difficulties 
in  the  campaign  against  this  disease,  we  are  unable,  in  the 
present  state  of  our  knowledge,  to  free  from  bacilli  those  carriers 
who  have  been  detected;  and  measures  suggested  to  minimize 
the  risks  of  infection — e.g.,  thorough  cleaning  and  disinfection 
of  hands  after  defsecation  and  urination,  and  continuous  disin- 


COMMUNICABLE   DISEASES  467 

fection  of  dejecta — are  not  likely  to  be  carried  out  by  most 
"  carriers,"  who  are  under  no  sort  of  control. 

The  bacilli  have  been  shown  by  Conradi  to  be  present  in  the 
blood  during  the  incubation  period,  and  even  before  the  bacilH 
can  be  found  the  presence  of  anti-bodies  may  be  demonstrated 
by  the  precipitin  test,  as  was  shown  by  Fornet.  With  the  aid 
of  the  Drigalski-Conradi  medium  and  the  agglutination  test, 
strong  evidence  of  the  presence  of  B.  typhosus  in  the  blood  may 
be  obtained  in  the  course  of  twenty-four  hours,  and  within  forty- 
eight  hours  this  evidence  may  be  confirmed  sufficiently  to  warrant 
the  undertaking  of  special  preventive  measures.  It  is  obvious 
that  methods  of  this  kind  must  be  more  generally  adopted  if  we 
are  to  obtain  full  information  with  regard  to  the  incubating  and 
mild  or  abortive  cases  which  contribute  such  a  large  proportion 
to  extensive  epidemics. 

Many  people  who  are  exposed  to  the  infection  of  both  enteric 
fever  and  cholera  escape,  owing  to  the  virus  being  destroyed  on 
swallowing  by  the  aid  of  the  gastric  juice.  But  those  who  are 
out  of  health,  or  who  are  suffering  from  diarrhoea,  may  offer  much 
less  resistance  to  the  invasion  of  the  contagion. 

Klein  has  shown  by  experiments  on  animals  that  the  virulence 
of  B.  typhosus,  and  to  a  less  extent  of  the  Vibrio  cholcrce,  may 
be  enhanced  by  association  (symbiosis)  with  certain  strains  of 
B.  coli,  with  the  Bacillus  of  Gaertner,  and  with  B.  enteritidis 
sporogenes  and  B.  carnis,  all  these  organisms  being  capable  of 
setting  up  gastro-enteritis,  when  they  happen  to  be  ingested  with 
the  specific  typhoid  or  cholera  organisms. 

Of  those  who  drank  the  infected  water  in  the  outbreaks  at 
Maidstone  and  Worthing  about  6  per  cent,  were  attacked  with 
the  disease.  But  this  figure  is  obtained  from  the  notification 
returns,  and  doubtless  many  cases  of  mild  infection  are  never 
notified;  so  that  the  incidence  of  infection  in  these  outbreaks 
probably  exceeded  10  per  cent. 

Apparent  insusceptibility  may  sometimes  be  explained  by 
the  possibility  that  the  disease  may  have  been  contracted  in 
childhood,  when  it  is  often  mild  and  unrecognizable,  for,  as  a 
rule,  one  attack  confers  immunity  for  the  remainder  of  life. 
No  age  and  neither  sex  is  free  from  risk  of  attack,  but  those 
from  fifteen  to  twenty-five  years  of  age  appear  to  be  specially 
prone  to  suffer.  Between  the  age  of  three  and  twenty  years  the 
mortality  of  females  from  enteric  fever  is  greater  than  that  of 


468  HYGIENE    AND    PUBLIC   HEALTH 

males.  The  higher  death-rate  at  these  ages  is  due,  not  to 
greater  habihty  on  their  part  to  contract  the  disease,  but  to  a 
higher  case  mortahty,  i.e.,  a  larger  proportion  of  attacks  proving 
fatal. 

During  the  period  1871-80  the  mortality  from  enteric  fever 
in  England  and  Wales  was  at  the  rate  of  033  per  1,000  living  at 
all  ages;  but  the  death-rate  from  this  disease  has  undergone  for 
a  long  period,  and  is  still  undergoing,  a  steady  and  sensible 
diminution  year  by  year.  In  1869  (the  first  year  in  which 
enteric  fever  returns,  as  separate  from  "  fever,"  are  obtainable) 
the  death-rate  was  0-39  per  1,000,  whilst  in  1910  the  death-rate 
was  only  0053  per  1,000,  a  sevenfold  reduction.  This  result 
may  be  attributed  to  the  improvements  in  water  supply,  sewerage 
and  domestic  sanitary  arrangements,  throughout  the  country 
generally,  that  have  been  so  marked  a  feature  in  the  social  pro- 
gress of  the  last  forty  years. 

The  proportion  of  deaths  to  attacks  in  enteric  fever  cannot 
be  accurately  stated,  owing  to  the  number  of  mild  cases  that 
escape  recognition.  In  typical  cases  the  mortality  varies  from 
15  to  20  per  cent,  of  the  attacks.  The  average  mortality  of 
cases  notified  in  London  is  14-1  per  cent.  (1911).  In  early  hfe 
the  type  of  the  disease  is  less  severe  than  in  adolescence  and 
adult  age. 

Enteric  fever  is  most  prevalent,  and  causes  the  largest  number 
of  deaths,  in  the  late  autumn.  The  seasonal  mortalit}^  curve 
{see  fig.  79)  is  seen  to  rise  in  August,  and  attain  its  maximum 
late  in  October  or  early  in  November,  from  which  point,  with 
the  exception  of  a  slight  rise  in  February,  it  gradually  faUs. 

It  is  now  established  that  the  infection  of  enteric  fever  may 
be  conveyed  in  shell-fish,  more  especially  in  oysters,  mussels, 
and  cockles,  which  are  collected  from  tidal  waters  where  the 
water  is  liable  to  considerable  pollution  from  sewage;  and  it 
has  been  shown  that  the  specific  bacilU  of  enteric  fever  and  of 
cholera  are  capable  of  existing  in  oysters  and  cockles  for  some 
days,  and  in  sea-water  for  several  weeks.  Klein  has  shown  that 
when  infected  oysters  are  kept  in  clean,  frequently  changed, 
sea- water,  they  rapidly  clear  themselves  of  the  bacilli.  Legisla- 
tive measures  are  therefore  required  in  the  interest  of  public 
health  to  prohibit  the  laying  down  of  oysters  in  dangerous 
localities;  and  to  that  end  all  oyster  layings,  fattening  beds, 
and  storage  ponds  should  be  made  registrable  after  approval  by 


COMMUNICABLE   DISEASES  469 

the  sanitary  authority,  and  also  subject  to  frequent  inspection. 
Section  4  of  the  Infectious  Diseases  (Prevention)  Act,  1890, 
which  enables  authorities  to  prohibit  the  supply  of  milk  which 
is  causing,  or  is  likely  to  cause,  disease,  might  also,  with  modifi- 
cations, be  made  to  apply  to  oysters  and  other  shell-fish.  The 
public  should,  moreover,  be  guarded  against  the  importation  of 
infected  oysters  from  abroad. 

The  presence  of  typical  B.  coli  communis  in  considerable 
numbers  in  the  body  of  the  shell-fish  is  usually  regarded  as 
sufficient  evidence  of  faecal  contamination,  as  in  shell-fish 
derived  from  waters  free  from  pollution  these  organisms  are  not 
found. 

It  is  noteworthy  that  in  enteric  fever  and  in  cholera,  especially 
when  due  to  polluted  water,  an  outbreak  is  often  preceded  for 
several  weeks  by  cases  of  "  diarrhoea,"  which  may  be  instances 
of  the  mild  or  "  ambulatory  "  type  of  the  disease.  For  instance, 
in  the  Spanish-American  war  of  1898  it  was  found  that,  in  the 
volunteer  camps,  15-3  per  cent,  of  the  soldiers  who  had  had 
no  previous  diarrhoea  developed  enteric  fever,  whereas  only 
6-8  per  cent,  of  those  who  had  so  suffered  developed  the 
disease. 

Where  flies  abound,  it  is  probable  that  enteric  fever  is  very 
frequently  transmitted  through  their  agency,  the  flies  directly 
conveying  the  contagion  on  their  hairy  legs  from  infected  excreta 
to  some  article  of  food.  Considerable  evidence  of  fly-borne 
enteric  has  accumulated  from  the  experiences  of  recent  military 
campaigns,  and  infected  dust  is  also  believed  to  be  an  agent  in  the 
transmission  of  the  disease. 

Maggots  bred  in  the  fasces  of  enteric  cases  do  not  produce 
infected  flies,  as  was  at  one  time  suggested.  The  B.  typhosus  has 
not  been  definitely  isolated  from  the  intestines  of  flies  so  bred. 
It  is  even  doubtful  if  the  B.  typhosus  is  ever  excreted  in  the  faeces 
of  flies  which  have  fed  on  enteric  stools,  the  B.  coli  in  the  flies' 
intestines  being  strongly  antagonistic  to  the  typhoid  organism. 
It  is  possible,  however,  that  the  vomit  from  the  crops  of  flies  which 
have  ingested  B.  typhosus  may  contain  the  organism.  This 
vomit,  or  regurgitation  from  the  crop,  is  a  common  act  when  a 
fly  is  feeding,  and  is  useful  in  softening  hard  material  which  the 
fly  is  endeavouring  to  absorb.  It  is  possible,  therefore,  that 
flies  convey  infection  by  organisms  carried  on  their  feet,  and  by 
regurgitations  from  their  crops  on  to  the  materials  on  which  they 


470  HYGIENE   AND   PUBLIC  HEALTH 

are  feeding.  At  any  rate,  laboratory  experiments  point  to  such 
methods  of  infection;  but,  so  far,  it  does  not  appear  that  any 
flies  have  been  captured  in  a  state  of  nature  which  have  been 
found  definitely  infected  with  undoubted  B.  typhosus. 

It  is  the  experience  of  numerous  localities  that  enteric  fever  may 
be  endemic  notwithstanding  a  water  supply  of  undoubted  purity. 
In  these  localities — generally  poor  and  crowded — there  are  sani- 
tary circumstances  which  generally  conduce  to  soil  pollution,  such 
as  defective  house  and  yard  drainage  and  sewerage,  unpaved  or 
badly  paved  yards  around  houses,  allowing  refuse  to  pollute  the 
soil,  and,  above  all,  defective  privy  middens  containing  con- 
siderable accumulations  of  excreta,  much  of  the  liquid  part  of 
which  finds  its  way  into  the  soil.  Many  observers  have  ascer- 
tained that  the  incidence  of  the  disease  is  always  heavier  on 
houses  with  dry  closets  than  on  those  with  water-closets;  and, 
among  the  former,  those  with  middens  are  more  frequently 
infected  than  those  with  pails,  the  difference  being  more  marked 
the  poorer  the  class  of  houses  (Boobyer).  Dr.  Newsholme  has 
pointed  out  that  Nottingham  and  Leicester  possessed  two 
features  in  common,  some  years  ago  :  a  conservancy  system  of 
excrement  disposal,  and  a  high  death-rate  from  enteric  fever. 
Whereas  Nottingham  has  made  but  slow  progress  in  the  adoption 
of  the  water-carriage  system,  in  Leicester  the  progress  has  been 
rapid ;  and  as  regards  enteric  fever  the  death-rate  in  Nottingham 
is  still  high,  while  that  in  Leicester  has  undergone  a  very  marked 
diminution.  Flies  and  dust  may  have  some  share  in  the  propa- 
gation of  infection  from  privies  and  middens  to  neighbouring 
dwellings ;  whilst  uncleanly  habits,  with  their  tendency  to  produce 
contact-infection,  are  favoured  by  the  retention  of  excretal 
matters  in  the  vicinity  of  houses. 

That  the  disease  is  frequently  communicated  by  personal 
intercourse  is  repeatedly  demonstrated  by  its  spread  to  those 
in  attendance  on  a  patient  in  dwelling-houses,  and  even  in  hos- 
pitals. 

Goodall  has  shown  from  the  experience  of  twelve  of  the  large 
Metropolitan  Fever  Hospitals  during  eight  years,  that  for  every 
1,000  cases  of  enteric  fever  admitted  as  many  as  sixteen  of  the 
staff  contracted  the  disease. 

Dr.  Childs,  from  a  study  of  the  chief  outbreaks  in  this  country, 
concludes  that,  where  the  public  water  supply  is  infected,  the  ex- 
plosive outburst  of  the  epidemic  is  not  indicated  by  notifications 


COMMUNICABLE    DISEASES  4^1 

until  two  or  three  weeks  after  the  actual  infection  comes  into 
operation;  that  the  abnormal  number  of  cases  of  antecedent 
diarrhoea  is  a  suggestive  premonitory  sign  of  an  outbreak  of 
enteric  fever,  and  should  be  bacteriologically  examined;  and 
that  a  large  proportion  of  those  who  are  infected  are  never 
notified. 

The  numerous  outbreaks  (Caterham,  Middlesbro,  Tees  Valley, 
Worthing  and  Maidstone)  in  which  the  disease  has  been  shown 
to  be  conveyed  through  the  medium  of  drinking  water,  point  to 
the  necessity  of  exercising  a  constant  supervision  and  sanitary 
control  over  all  sources  of  drinking  water,  both  by  the  establish- 
ment of  protected  areas  upon  the  sites  from  which  water  is  col- 
lected for  drinking  purposes,  and  also  by  systematically  ascertain- 
ing the  degree  of  purity  of  the  water  by  means  of  repeated 
chemical  and  biological  examinations. 

Pettenkofer  has  shown  that  in  Munich  there  was  a  remarkable 
correspondence  between  the  rise  of  the  subsoil  water  and  the 
dechne  in  the  prevalence  of  enteric  fever,  and  vice  versa.  He 
does  not  profess  to  explain  this  relationship,  but  demonstrates 
that  the  movements  of  the  ground  water  were  an  invariable  index 
to  the  extent  of  enteric  fever  incidence  in  Munich. 

The  serum  diagnosis  of  enteric  fever  (Widal)  is  an  important 
means  of  aiding  the  clinical  diagnosis  of  the  disease;  and  since 
it  is  in  the  public  interest  that  the  diagnosis  should  be  prompt 
and  certain  in  the  case  of  a  disease  which  so  often  has  a  masked 
and  insidious  onset,  many  sanitary  authorities  now  provide 
medical  practitioners  with  a  so-called  "  diagnosis  outfit,"  con- 
taining a  small  capillary  tube  for  collecting  and  sealing  up 
some  of  the  blood  of  a  suspected  patient.  The  blood  is  returned 
to  the  local  offices,  where  arrangements  are  made  for  testing  it 
at  the  public  expense.  The  diagnosis  outfit  also  comprises  a 
sterilized  swab  in  a  tube  for  collecting  suspected  exudation  or 
membrane  from  the  throats  of  patients  thought  to  be  suffering 
from  diphtheria.  Similar  provisions  have  also  been  made  in 
some  districts  for  enabling  medical  practitioners  to  avail  them- 
selves of  the  bacteriological  diagnosis  of  tuberculous  sputum. 
Such  diagnoses  add  definiteness  to  administrative  procedure, 
qud  isolation,  disinfection,  and  the  admission  of  patients  to 
hospital  wards. 

The  evidence  so  far  recorded  of  Widal's  test  establishes  the 
fact  that  the  reaction  of  the  blood  on  the  Bacilli  typhosus,  causing 


45?^  HYGIENE  AND  PUBLIC  HEALTH 

a  characteristic  clumping  of  the  latter,  and  a  total  arrest  of 
motion  within  a  definite  time  limit,  may  be  delayed,  or  occasion- 
ally may  not  be  obtained,  in  cases  of  genuine  typhoid  infection ; 
and  also  that  it  may  in  some  instances  occur  in  non-typhoid  cases, 
though  not  in  an  intense  degree,  nor  if  high  dilution  of  the  serum 
be  used.  The  average  of  successful  diagnoses  approximates, 
however,  to  90  per  cent. 

In  carrying  out  this  method  of  diagnosis,  all  that  is  necessary  is 
to  draw  a  small  quantity  of  blood  from  the  finger  or  ear  of  the 
patient  into  a  capillary  tube.  The  serum  reaction  is  performed 
by  diluting  the  serum  25,  50,  or  100  times  with  a  typhoid  broth  or 
emulsion,  and  then  making  "  hanging-drop  "  preparations  of  the 
different  dilutions,  which  are  examined  under  the  microscope  for 
signs  of  clumping  and  loss  of  motility  in  the  bacilli.  A  time  limit 
of  half  to  two  hours,  according  as  the  dilution  is  a  low  or  high 
one,  is  given  by  most  bacteriologists. 

The  value  of  anti-typhoid  inoculations  is  now  obtaining  general 
recognition.  The  material  generally  used  for  anti-typhoid  inocu- 
lation is  a  suspension  of  the  dead  bacilli  obtained  from  a  culture 
killed  by  heat. 

Forty-eight-hour-old  bouillon  cultures  of  a  laboratory  strain 
of  B.  typhostis  are  used,  and  are  killed  by  heating  for  an  hour  at 
53°  C.  Lysol  is  added  as  an  antiseptic  in  the  proportion  of 
04  per  cent,  of  the  whole  volume  of  the  vaccine  (Leishman). 
Usually  two  inoculations  are  given,  with  an  interval  of  ten  days, 
the  dose  of  the  first  inoculation  being  500  millions  of  bacilli,  and 
of  the  second,  1,000  millions.  The  results  of  anti-typhoid  inocu- 
lation in  the  British  Army  have  been  extremely  good,  the  number 
of  cases  of  enteric  fever  occurring  among  non-inoculated  soldiers 
serving  abroad  being  more  than  five  times  as  great  as  amongst 
the  inoculated.  The  severity  of  attack  is  markedly  less  in  the 
inoculated  men,  and  there  are  a  smaller  proportion  of  complica- 
tions and  relapses.  It  is  a  question  now  whether,  when  troops 
are  going  to  places  like  India,  where  paratyphoid  fevers  are  not 
uncommon,  it  would  not  be  advisable  to  make  the  vaccines  poly- 
valent for  these  diseases  as  well  as  for  enteric  fever. 

The  use  of  living  B.  typhosi  has  been  recommended  for  anti- 
typhoid inoculations  instead  of  cultures  killed  by  heat,  with  the 
idea  of  establishing  a  greater  and  a  more  prolonged  immunity 
than  is  now  possible  (a  period  of  less  than  two  years).  It  has 
also  been   ascertained   that   anthropoid  apes  can  be  rendered 


COMMUNICABLE   DISEASES  473 

immune  to  enteric  fever  by  living  cultures  of  B.  typhosus,  but  not 
by  dead.  If  living  cultures  are  injected,  in  order  to  prevent 
severe  general  reactions,  only  non- virulent  organisms  which  have 
been  subcultured  for  months  or  years  in  a  laboratory  should  be 
used,  and  the  culture  should  be  heated  to  49°  C.  for  one  hour 
before  use  (Castellani) .  If  virulent  strains  of  B.  typhosus  are  used, 
they  should  first  be  sensitized  (rendered  non-virulent)  by  mixing 
them  with  horse-typhoid  immune  serum.  So  far,  there  are  no 
available  statistics  as  to  the  comparative  results  obtained  by 
immunizing  with  dead  or  living  bacilli  respectively. 

Diarrhcea. 

Diarrhoea  is,  of  course,  merely  a  symptom  of  very  many  dis- 
eases. But  in  the  sense  here  understood  it  means  those  acute 
specific  attacks  of  illness  of  which  the  diarrhoea  is  the  most 
prominent  symptom,  which  occur  so  generally  in  persons  of  all 
ages,  but  more  especially  in  infants  and  young  children,  towards 
the  middle  or  close  of  the  summer.  The  death-rate  from  diar- 
rhoeal  complaints  remains  remarkably  constant  through  the 
winter  and  spring,  but  with  the  onset  of  hot  summer  weather 
in  many  large  towns  an  extensive  outbreak  occurs,  the  chief 
incidence  of  which  falls  upon  those  at  the  two  extremes  of  life, 
or  who  are  enfeebled  in  health.  This  epidemic  diarrhoea  is  in 
many  cases  of  a  choleraic  nature,  accompanied  by  cramps, 
spasms,  and  signs  of  collapse,  and  appears  to  be  due  to  con- 
sumption of  tainted  food,  or  of  impure  water,  or  to  the  breathing 
of  fouled  air.  The  putrefactive  changes  which  occur  in  food 
and  fouled  water  or  soil  are  all  more  rapid  and  intense  under 
the  influence  of  a  high  temperature;  and  it  is  quite  reasonable 
to  believe  that  many  of  these  diarrhoeal  attacks  are  due  to  the 
action  of  the  bacterial  agents  of  putrefaction,  or  of  their  products, 
when  taken  into  the  system. 

In  some  of  these  cases  of  acute  diarrhoea,  the  B.  enteritidispi 
Gaertner  has  been  found,  whilst  other  cases  of  epidemic  diarrhoea 
are  associated  with  the  B.  enteritidis  sporogenes — -a  sporing 
anaerobic  organism  first  isolated  by  Klein  from  milk  sold  in 
small  retail  shops,  and  since  found  in  sewage,  in  water  polluted 
by  sewage,  in  the  excreta  of  patients  suffering  from  diarrhoea, 
in  horse  dung,  and  in  various  articles  of  food.  Morgan,  working 
at  the  Lister  Institute  for  Preventive  Medicine  on  stools  of 
patients  suffering  from  summer  diarrhoea  in  the  London  Hos- 


474  HYGIENE    AND    PUBLIC    HEALTH 

pitals,  found  a  bacillus  of  the  non-fermenting  lactose  group  to 
be  the  predominant  organism.  This  is  now  known  as  Morgan's 
bacillus.  But  it  appears  probable  that  summer  diarrhoea  is 
due  to  several  associated  organisms  of  the  coli  type. 

Many  different  terms  are  employed  to  designate  the  disease 
officially  known  as  "  epidemic  diarrhoea,"  and  this  fact  leads  to 
great  difficulties  in  classifying  death  returns.  The  terms  em- 
ployed include  : — diarrhoea,  epidemic  diarrhoea,  dysentery  and 
dysenteric  diarrhoea,  intestinal  (or  enteric)  catarrh,  gastro- 
intestinal (or  gastro-enteric)  catarrh,  gastro-enteritis,  muco- 
enteritis,  and  gastric  catarrh.  This  confusion  of  terms  leads  to 
much  discrepancy  in  the  classification  of  death  returns;  and 
early  in  1900  the  Royal  College  of  Physicians  authorized  the  use 
of  the  term  "  epidemic  enteritis  "  or,  if  preferred  by  the  prac- 
titioner, "  zymotic  enteritis,"  as  a  synonym  for  epidemic  diar- 
rhoea, and  recommended  the  entire  disuse  of  the  other  terms 
mentioned  above. 

Dysentery  arises  in  a  very  similar  way  to  diarrhoea.  The 
effect  of  a  chill,  on  which  so  much  stress  has  been  laid,  is  probably 
to  increase  the  susceptibility  of  the  system  to  the  poison.  It 
may  be  that  chilling  sets  up  a  slight  enteritis,  whereby  the 
normal  resisting  power  of  the  lymphoid  tissue  in  the  bowel  wall 
is  lowered,  so  that  the  organisms  present  in  the  bowel  are 
enabled  to  get  a  foothold  and  multiply  in  the  intestinal  walls. 
Attacks  of  dysenteric  diarrhoea,  with  discharges  of  blood  and 
mucus  per  rectum,  are  occasionally  associated  with  outbreaks  of 
diarrhoea  in  this  country,  and  are  not  uncommon  amongst  the 
inmates  of  lunatic  asylums.  It  is  then  known  as"  colitis,"  and 
is  probably  communicable  from  the  sick  to  the  healthy  (Mott 
and  Durham). 

Although  it  is  unquestionable  that  dysentery  and  acute  diar- 
rhoea in  the  vast  majority  of  cases  appear  to  arise  de  novo  (indepen- 
dently of  the  contagion  of  a  previous  case),  yet  it  is  certain  that 
the  diarrhoeal  evacuations  help  to  spread  the  disease  in  certain 
instances.  It  has  been  shown  that  the  infection  may  be  carried 
in  water,  and  boiling  the  drinking  water  has  stopped  the  out- 
break. 

Some  years  ago,  Dr.  Hope  of  Liverpool  conducted  an  inquiry 
in  order  to  determine  the  relative  mortality  from  diarrhoea 
among  infants  of  artisan  parents,  classified  as  follows  :  First,  the 
entirely  breast-fed;  secondly,  those  fed  partly  on  breast  milk 


COMMUNICABLE    DISEASES  475 

and  partly  on  artificial  food;  and,  thirdly,  the  entirely  artificially 
fed.  He  found  that  for  every  death  from  diarrhoea  which 
occurred  among  breast-fed  infants  under  three  months  old, 
fifteen  occurred  among  those  of  the  mixed  class,  and  that  for 
every  death  from  the  same  cause  among  the  breast-fed  and 
mixed  class  combined,  twenty-two  occurred  among  the  entirely 
artificially  fed. 

From  the  seasonal  curve  for  diarrhoea  it  appears  that  the 
mortality  begins  to  increase  about  the  middle  of  June,  rises 
rapidly  to  its  maximum  at  the  end  of  July  or  early  in  August, 
and  falls  somewhat  less  rapidly  throughout  August,  September, 
and  October.  The  following  is  a  very  brief  epitome  of  Dr. 
Ballard's  observations  : — 

The  summer  rise  of  diarrhoeal  mortality  in  the  large  towns 
does  not  commence  until  the  mean  temperature  recorded  by 
the  earth  thermometer,  placed  four  feet  below  the  surface,  has 
attained  somewhere  about  56°  F. — no  matter  what  may  have 
been  the  temperature  previously  attained  by  the  atmosphere, 
or  recorded  by  the  i-foot  earth  thermometer.  The  maximum 
diarrhoea  mortahty  of  the  year  is  usually  observed  in  the  week 
when  the  4-foot  earth  thermometer  attains  its  mean  weekly 
maximum.  The  diarrhoea  mortality  declines  with  the  4-foot 
earth  thermometer,  and  this  decline  takes  place  very  much  more 
slowly  than  that  of  the  atmospheric  temperature  or  of  the  i-foot 
earth  thermometer,  so  that  the  mortality  from  epidemic  diarrhoea 
may  continue  long  after  the  air  temperature  has  fallen,  even 
into  the  fourth  quarter  of  the  year. 

The  earth  temperature  at  a  depth  of  4  feet  is  valuable  as  a 
measure  of  the  cumulative  effect  of  the  sun's  heat,  the  variations 
in  earth  thermometers  following  those  of  a  thermometer  above 
ground  at  an  interval  of  about  three  or  four  days.  On  an 
average,  twenty-four  hours  are  required  for  the  sun's  heat  to 
penetrate  to  a  depth  of  i  foot,  the  actual  time  varying  somewhat 
with  different  soils. 

The  soils  most  favourable  to  a  high  diarrhoea  mortality  are 
those  of  sand,  gravel,-  or  marl  (in  which  the  constituent  particles 
are  small  but  freely  permeable  by  air  and  water),  and  which 
contain  organic  matters  of  animal  origin  from  "  made  ground," 
from  manured  surfaces,  or  from  soakage  of  excretal  refuse  from 
privies,  cesspools,  and  sewers.  The  soil  must  be  moist,  but  the 
moisture  must  not  be  sufficient  to  preclude  the  free  admission 


476  HYGIENE    AND   PUBLIC   HEALTH 

of  air  between  the  interstices;  the  moisture  of  the  soil  may 
arise  from  surface  water  sinking  into  the  earth  around  houses, 
as  well  as  from  capillary  attraction  of  a  high  subsoil  water  from 
below. 

Oth^r  factors  conducive  to  a  high  diarrhoea  mortality  are 
domestic  overcrowding,  darkness  and  dirtiness  of  premises,  and 
the  keeping  of  milk  and  other  foods  in  underground  cellars  ex- 
posed to  telluric  emanations,  or  in  pantries  hable  to  the  entry 
of  drain  or  sewer  air. 

It  is  also  very  probable  that  milk  kept  in  open  jugs,  and  other 
articles  of  food,  become  infected  with  the  Bacillus  enteritidis 
sporogenes  and  other  organisms,  through  the  agency  of  flies  and 
of  dust  containing  particles  of  horse  excreta  from  the  streets. 
Among  the  more  important  preventive  measures  must  there- 
fore be  placed  domestic  cleanliness,  the  prompt  removal  from 
dwellings  of  animal  and  vegetable  refuse  (the  breeding  place  of 
flies),  the  protection  of  food  from  flies,  the  exposure  of  "  fly- 
papers "  in  the  best  lighted  parts  of  rooms,  and  the  more  frequent 
cleansing  and  watering  of  streets  and  yards  in  dry  weather,  so 
as  to  reduce  dust. 

As  previously  stated,  the  disease  is  mainly  one  of  early  child- 
hood (0-5  years),  over  80  per  cent,  of  the  mortality  occurring 
under  two  years  of  age;  but  its  incidence  is  by  far  the  greatest 
on  hand-fed  infants,  hence  female  factory  labour,  by  depriving 
infants  of  their  natural  food,  is  a  contributing  cause.  The 
attacks  are  usually  extremely  sudden  in  their  onset;  and  that 
diarrhoea  is  merely  one  symptom  or  feature  of  the  illness  is  shown 
by  the  fact  that  many  of  the  organs  of  those  who  have  succumbed 
are  found  to  be  highly  degenerated,  more  especially  the  kidneys, 
the  Hver  (fatty  degeneration),  and  the  spleen.  The  lungs,  too, 
are  often  the  seat  of  pneumonic  inflammation. 

Dr.  Newsholme's  researches  point  to  the  following  circum- 
stances as  determining  the  incidence  of  diarrhoea  :  (i)  Towns  with 
water-carriage  sewage  have,  as  a  rule,  less  diarrhoea  than  those 
practising  other  methods  of  removal.  (2)  Towns  with  the  most 
perfect  scavenging  arrangements  have  least.  (3)  Towns  having 
the  lowest  diarrhoeal  mortalities  are  situated  on  impervious  soils, 
though  the  converse  scarcely  holds  good;  and  steep  gradients 
favour  a  low  diarrhoeal  rate.  (4)  Given  two  towns,  alike  in 
sanitary  and  social  circumstances,  the  rate  is  proportionate  to 
the  height  of  the  temperature  and  the  deficiency  of  rainfall,  more 


COMMUNICABLE  DISEASES  477 

particularly  during  the  third  quarter.  (5)  There  is  a  general 
inverse  relationship  between  rainfall  and  diarrhoea,  and  a  direct 
relationship  between  temperature  and  diarrhoea.  (6)  The  soil 
is  a  great  factor  in  the  causation  of  diarrhoea,  but  its  influence 
may  be  largely  discounted  by  impervious  paving  in  streets  and 
yards  and  impervious  flooring  to  houses.  (7)  The  incidence  of 
diarrhoea  follows  more  closely  the  want  of  rainfall  than  the  mean 
temperature  of  the  air;  and  the  efficient  washing  of  streets, 
swilling  of  yards,  and  flushing  of  sewers  reduces  it.  (8)  The 
disease  increases  largely  in  prevalence  when  the  4- foot  earth 
thermometer  reaches  56°  F.,  or  when  the  mean  weekly  tempera- 
ture of  the  air  rises  to  about  63°  F. 

Preventive  measures  are  mainly  designed  to  prevent  the 
pollution  of  the  air  and  soil  in  and  around  houses,  to  encourage 
the  practice  of  habits  of  domestic  cleanliness,  and  the  protection 
of  food  from  all  sources  of  pollution.  More  especially  during 
the  summer  months  should  all  milk  be  boiled  shortly  before  use, 
and  the  feeding  bottles  for  infants  should  be  kept  scrupulously 
clean.  All  foods  should  be  stored  in  a  light  airy  place  and  care- 
fully protected  from  dust  and  flies;  fruit  and  vegetables  should 
be  thoroughly  cleaned  before  consumption ;  and  no  tainted  food 
or  unripe  or  overripe  fruit  should  be  eaten.. 

During  the  decennium  1891— 1900,  the  death-rate  in  England 
and  Wales  from  diarrhoeal  disease  was  073  per  1,000  living  at  all 
ages.  Under  five  years  of  age,  the  death-rate  was  4-3  per  1,000 ; 
and  although  this  high  rate  is  largely  contributed  to  by  the 
improper  feeding  of  infants,  there  can  be  no  doubt  that  insanitary 
conditions,  of  the  kinds  named  above,  play  a  large  part  in  its 
production.  For  the  ten  years  1871—80,  the  death-rate  in 
England  and  Wales  from  diarrhoeal  diseases  was  093  per  1,000 
living  at  all  ages,  and  for  the  ten  years  1881—90,  068  per  1,000. 
For  the  four  years  1907—10,  the  rate  averaged  0-35  per  1,000. 

House-Flies. — ^The  commonest  species  of  house-fly,  and  the 
most  predominant  in  the  interior  of  houses,  is  Musca  domestica. 
Next  comes  the  lesser  house-fly,  Homalomyia  caiiicularis,  and 
then  the  blue-bottle  flies,  CalUphora  vomitoria. 

Musca  lays  its  eggs  by  preference  in  horse  manure,  but  will 
also  lay  in  cow-dung,  human  and  other  excrement,  and  ashbin 
refuse.  The  usual  period  from  the  laying  of  the  egg  to  the  pro- 
duction of  the  fly  is  from  eight  to  twenty  days.  Absence  of 
gn.^CJent  moisture,  warmth,  and  food    for   the  larvae  leads  to 


478  HYGIENE   AND    PUBLIC    HEALTH 

delayed  development  or  to  the  production  of  small  and  imperfecl 
flies.  Flies  become  ^sexually  mature  in  from  two  to  three  weeks 
after  hatching  out.  A  female  fly  will  lay  from  four  to  six  batches 
of  eggs,  each  batch  containing  from  120  to  150  eggs.  The  eggs 
are  deposited  in  holes,  crevices,  or  shaded  places  in  collections 
of  dung,  human  or  animal  excreta,  or  refuse  heaps. 

In  about  three  days  from  the  eggs  being  laid  larvae  can,  if 
necessity  arises,  leave  their  food-supply  in  excreta,  and  take 
refuge  in  the  ground,  there  to  undergo  pupation.  The  larvae 
pass  through  three  stages  of  varying  durations,  under  favourable 
conditions  the  three  stages  being  completed  in  less  than  fourteen 
days.  The  development  of  the  imago  will  take  four  or  five  days 
longer.  The  larvag  require  warmth  and  moisture,  whilst  the 
pupae  require  warmth  and  dryness.  These  conditions  are  best 
afforded  in  collections  of  horse  manure.  Although  all  species  of 
house-fly  are  exceedingly  prolific,  the  numbers  in  any  season 
are  largely  affected  by  such  adverse  conditions  as  low  air  tempera- 
tures, heavy  rainfall,  and  absence  of  suitable  material  for  the 
development  of  the  larvae. 

A  fly  will  live  six  weeks,  or  even  longer,  in  a  favourable  season. 
Flies  travel  with  the  wind,  and  under  favourable  circumstances 
may  traverse  a  distance  of  half  a  mile  within  an  hour. 

Flies  will,  under  suitable  conditions,  breed  in  winter,  and  there 
can  be  little  doubt  that  the  seasons  are  connected  by  living  flies, 
and  not  by  pupae.  The  spring  increase  usually  commences  in 
April  or  May  in  covered  collections  of  fermenting  horse  manure. 
The  great  upward  rise  in  the  curve  of  fly  prevalence  is  usually  seen 
to  commence  in  the  first  week  of  July,  a  maximum  being  reached 
some  time  in  August  or  September,  according  to  the  air  tempera- 
tures prevailing  in  any  particular  year.  With  the  commence- 
ment of  October,  a  sharp  decline  in  fly  prevalence  usually  sets 
in.  This  annual  decline  is  partly  due  to  the  onset  of  cold  weather, 
which  causes  the  flies  to  become  lethargic  and  to  remain  indoors, 
so  that  fewer  eggs  are  laid  in  dung  and  refuse,  and  partly  to  the 
destruction  effected  amongst  the  larvae  by  a  beetle — the  Empiisa 
musccB — which  increases  largely  in  numbers  in  August  and  Sep- 
tember, and  kills  innumerable  larvae. 

Although  in  some  years  in  urban  populations  there  is  often  a 
considerable  amount  of  correspondence  between  the  curves  of 
fly  prevalence  and  of  diarrhoea  prevalence  or  mortality,  still 
.this  correspondence  is  by  no  means  invariable;  and  it  has  been 


COMMUNICABLE    DISEASES 


479 


Egg. 


MUSCA  DOMESTICA   (after  Hewitt). 


'^>^^    „ 


Fig.  Si. 


Larva 

ATCHED 

FROM  Egg. 


Larva. 


Pupa. 


Fig.  82. — Diagrammatic  Section  of  Fly. 

/>,  pump  ;  /,  labella  ;  g-,  gullet ;  s.i/,  salivary  duct ;  s,  stomach  ;  c,  crop  ; 
2,  intestine  ;  ; ,  rectum. 


Fig.  83. — Leg  and  Foot  of  Fly. 


Fig.  84. — Fly  extruding  Bubble  from  Crop. 


480  HYGIENE    AND    PUBLIC    HEALTH 

noted  on  more  than  one  occasion  that  the  diarrhceal  curve 
begins  to  decline  some  time  before  the  fly  curve  begins  to  drop, 
whilst  the  uprises  of  the  two  curves  in  successive  years  often 
present  dissimilar  features  or  discrepancies,  which  would  hardly 
be  observed  if  flies  stood  to  diarrhoea  in  the  direct  relation  of 
cause  and  effect. 

Tuberculosis. 

Tuberculosis  is  a  disease  to  which  all  warm-blooded  animals 
appear  to  be  susceptible.  The  degree  of  susceptibihty  varies 
amongst  different  races  of  men,  and  amongst  individuals  of  the 
same  race.  The  offspring  of  phthisical  parents  appear  to  be  born 
with  a  certain  degree  of  susceptibility  of  tissue  to  attack  by 
tubercle.  It  is  for  this  reason  that  the  disease  was  believed  to  be 
hereditarily  transmissible.  If,  however,  the  disease  is  congenital 
at  all — i.e.,  directly  transmissible  from  parent  to  child — it  can 
only  be  so  to  a  very  trifling  extent.  Bang  has  shown  that  when 
the  calves  of  tuberculous  cows  are  separated  from  their  mothers 
and  placed  under  hygienic  conditions,  they  do  not  develop 
tubercle  in  any  greater  degree  than  the  calves  from  healthy 
parents.  He  found  that  tubercular  lesions  at  birth  are  extremely 
rare,  and  when  present  are  due  to  infection  through  the  placental 
circulation.  Investigations  by  Delepine,  Boltz,  etc.,  show  no 
observed  tuberculosis  in  the  first,  second,  and  third  weeks  of  life ; 
and  Koch  has  found  that  guinea-pigs  remain  healthy  if  reared 
apart  from  tuberculous  parents. 

The  universality  of  the  infection  and  the  extent  of  human 
resistance  are  demonstrated  by  the  circumstance  that  post- 
mortem examinations  of  persons  of  over  forty  years  of  age  very 
generally  disclose  some  old  localized  tuberculous  lesion  in  the 
lungs,  although  such  persons  have  never  suffered  from  the  disease 
in  a  recognizable  form. 

In  the  opinion  of  Metchnikoff,  in  the  civihzed  populations  of 
modern  times,  large  numbers  of  children  in  early  hfe  are  invaded 
by  the  tubercle  bacillus  in  small  dosage  or  in  attenuated  form, 
and  thereby  acquire  an  immunity  in  greater  or  less  degree  to 
subsequent  invasion  by  virulent  organisms  in  effective  doses. 

According  to  Behring's  view,  the  majority  of  human  tuber- 
culosis is  acquired  during  infancy,  and  remains  latent  in  the 
glands  until  circumstances  render  the  body  a  suitable  soil  for 
the  multiplication  of  the  germ. 

The  Registrar-General  includes  in  the  term  "  tuberculosis," 


COMMUNICABLE   DISEASES  48I 

"  phthisis,"  "  tabes  mesenterica,"  "  tubercular  meningitis,"  and 
"  other  forms  of  tubercular  disease  and  scrofula." 

If  the  vital  statistics  of  tuberculosis  in  this  country  during  the 
past  half-century  are  studied,  it  is  found  that — • 

1.  There  has  been  a  marked  and  progressive  reduction  in  the 
death-rate,  and  that  the  reduction  is  most  marked  during  the 
10-35  years  age-period. 

2.  There  has  been  a  still  greater  reduction  (of  nearly  50  per 
cent.)  in  the  death-rate  from  pulmonary  tuberculosis  or  phthisis, 
this  reduction  having  been  most  marked  at  the  several  age- 
periods  ranging  from  infancy  up  to  thirty-five  years,  and  greatest 
among  females. 

3.  Children  under  five  years  of  age  have  a  higher  mortality 
from  tuberculosis  than  exists  at  any  subsequent  five-year  age- 
period,  and  this  circumstance  is  due  to  the  greater  prevalence 
of  forms  other  than  phthisis.  This  fact  seems  to  point  to  the 
disease  being  maintained  among  infants  through  the  agency  of 
infected  milk,  but  some  of  the  increase  may  be  due  to  a  more 
extended  use  of  the  term  "  tabes  mesenterica  "  in  the  registra- 
tion of  infantile  deaths. 

The  principal  predisposing  causes  of  the  disease  are:  Foul  air 
{vide  pp.  175,  176) ;  dusty  occupations  (the  male  death-rate  from 
tuberculosis  of  the  lungs  is  nearly  half  as  much  again  as  the 
female);  dampness  of  site  and  of  premises;  dirtiness  and  dark- 
ness of  dwelling;  poverty  with  its  attendant  insufficiency  of  food 
and  liabiUty  to  exposure;  and  alcoholism.  Tissue  injuries  and 
malformations  of  the  chest  are  less  prominent  predisposing  causes. 
The  part  which  "  overcrowding  "  and  foul  air  play  in  promoting 
the  prevalence  of  phthisis  is  well  shown  at  Salford  (Dr.  Barry 
and  Mr.  Gordon  Smith's  inquiries — data  suppHed  by  Dr.  Tatham). 
Thus,  in  districts  where  all  the  houses  were  built  on  the  vicious 
system  known  as  "  back  to  back,"  the  phthisis  death-rate  was 
52  per  1,000  living;  where  56  per  cent,  of  the  houses  were  so 
built,  the  rate  was  36;  where  23  per  cent,  only  were  so  con- 
structed, it  was  further  reduced  to  3-3;  and,  lastly,  where  there 
were  no  "  back  to  back  "  houses — that  is  to  say,  where  all  the 
houses  were  provided  with  some  means  of  hght  and  air  both  in 
front  and  to  the  rear— the  rate  was  only  2-8  per  1,000.  These 
results  are  all  the  more  remarkable  because,  with  the  exception 
of  the  absence  of  means  for  through  ventilation,  the  back  to  back 
houses  on  the  whole  were,  in  Dr.  Tatham's  opinion,  in  better 

31 


482  HVGmN£  AND   PUBLIC   HEALTH 

Sanitary  condition  than  the  other  houses.  Similar  results  have 
been  obtained  by  other  observers  and  by  Dr.  Darra  Mair,  of  the 
Local  Government  Board  (see  Report  of  Medical  Officer  oj  the 
Local  Government  Board,  1908-9,  p.  xix). 

Buchanan  has  shown  that  the  effect  of  drying  the  soil,  in  the 
case  of  towns  where  the  level  of  the  subsoil  water  was  previously 
high,  was  to  greatly  diminish  (by  \  to  ^)  the  death-rate  from 
phthisis.  The  connection  between  phthisis  and  moisture  in  the 
soil,  which  had  been  previously  pointed  out  by  Bowditch  of 
Massachusetts,  was  thus  confirmed  by  Buchanan. 

The  materies  morbi,  the  bacillus  of  tubercle,  is  contained  in  the 
expectoration  of  phthisical  persons.  When  this  is  allowed  to 
dry  and  mingle  with  the  dust  of  rooms  and  streets,  the  bacillus 
may  be  inhaled  by  others,  and  so  infect  them.  Dujardin- 
Beaumetz  gives  a  striking  history  of  eleven  out  of  twenty-three 
clerks  in  an  office  being  attacked  during  the  course  of  twelve 
years,  as  the  result  of  the  introduction  of  the  disease  by  the 
first  sufferer.  The  floor  of  the  office  was  rough,  no  spittoons 
were  provided,  and  the  air  was  dust-laden  from  recent  sweeping 
when  the  men  arrived  in  the  morning.  The  floor  was  planed 
and  beeswaxed,  expectoration  was  prohibited  except  into  the 
spittoons  which  were  supplied,  and  the  cleansing  done  overnight, 
as  far  as  possible,  with  damp  cloths,  with  the  result  that  no 
further  cases  occurred. 

The  infection  may  also  be  swallowed,  or  directly  inoculated 
from  discharges.  As  already  stated,  milch  cows  are  particularly 
susceptible  to  tuberculosis,  and  in  advanced  cases  of  the  disease 
their  milk  may  contain  the  bacillus  (see  p.  372).  The  flesh  of 
bovines,  when  eaten  in  a  partially  cooked  condition,  may  also  be 
capable  of  conveying  the  disease. 

Dr.  Koch  has  maintained  that  human  tuberculosis  differs  from 
bovine  tuberculosis,  and  cannot  be  transmitted  to  cattle;  and 
he  further  holds  that  bovine  tuberculosis  is  scarcely,  if  at  all, 
transmissible  to  man.  The  former  conclusion  is  based  on  experi- 
ments, in  which  he  failed  to  infect  nineteen  young  cattle  (and 
subsequently  asses,  sheep,  and  goats)  with  human  tubercle  bacilli, 
but  he  invariably  succeeded  when  he  used  tubercle  bacilli  of 
bovine  source.  The  second  conclusion  is  based  upon  the  con- 
tention that  if  meat  and  milk  introduce  the  infection  into  man, 
there  must  be  in  the  latter  primary  tubercular  lesions  in  the 
intestines,  and  these  are  believed  to  be  rare. 


COMMUNICABLE    DISEASES  483 

Dr.  Koch's  views  have  not  met  with  much  support  from  other 
authorities,  but  owing  to  his  great  position  as  a  bacteriologist, 
the  Enghsh  Government  considered  it  desirable  to  refer  the 
whole  question  to  a  Royal  Commission,  which  has  already  issued 
three  reports. 

The  conclusions  arrived  at  by  the  Royal  Commission  appointed 
to  inquire  into  the  relations  of  human  and  bovine  tuberculosis  arc 
given  in  the  Second  Interim  Report  (1907)  as  follows: — "  There 
can  be  no  doubt  but  that  in  a  certain  number  of  cases  the  tuber- 
culosis occurring  in  the  human  subject,  especially  in  children,  is 
the  direct  result  of  the  introduction  into  the  human  body  of  the 
bacillus  of  bovine  tuberculosis;  and  there  also  can  be  no  doubt 
that  in  the  majority  at  least  of  these  cases  the  bacillus  is  intro- 
duced through  cow's  milk.  Cow's  milk  containing  bovine 
tubercle  bacilli  is  clearly  a  cause  of  tuberculosis  and  of  fatal 
tuberculosis  in  man." 

Out  of  sixty  cases  of  human  tuberculosis  investigated  by  the 
Royal  Commission,  in  14  or  23  per  cent,  the  tuberculous  material 
obtained  from  the  cases,  when  injected  subcutaneously  into  calves 
in  the  form  of  emulsions,  either  prepared  directly  from  the 
original  material,  or  indirectly,  from  the  tuberculous  organs  of 
guinea-pigs  infected  with  that  material,  was  found  capable  of 
producing  a  generalized  progressive  tuberculosis  in  the  experi- 
mental animals.  The  Commission  found  that  this  generalized 
progressive  tuberculosis  was  due  to  the  virus  containing  the 
bacilli  of  bovine  tuberculosis,  and  that  the  vira  containing  the 
bacilli  of  human  tuberculosis,  in  which  a  bovine  source  could  be 
excluded,  were  far  less  virulent  to  bovine  animals,  and  could  not 
set  up  in  them  a  generalized  progressive  tuberculosis. 

Out  of  the  sixty  cases  of  human  tuberculosis  investigated  by 
the  Royal  Commission,  twenty-eight  possessed  cHnical  histories 
indicating  that  in  them  the  bacillus  was  introduced  into  the  body 
through  the  alimentary  canal.  Of  these  twenty-eight  cases, 
thirteen,  or  46  per  cent.,  were  shown  to  contain  the  virulent  form 
of  organism,  which  alone  produces  in  bovine  animals  a  generalized 
progressive  tuberculosis,  and  which  was  therefore  identical  with 
the  bacillus  of  bovine  tuberculosis. 

The  above  facts  seem  to  indicate  that  a  very  considerable  pro- 
portion of  the  human  tuberculosis  contracted  by  ingestion  and 
primary  invasion  of  the  abdominal  organs,  is  due  to  tubercle 
bacilli  of  bovine  source. 


484  HYGIENE   AND   PUBLIC  HEALTH 

Under  the  term  "pseudo-tuberculosis"  a  whole  series  of 
lesions,  similar  to  those  induced  by  the  Bacillus  tuberculosis, 
is  included.  This  condition,  which  is  rare  in  man,  is  mostly 
caused  by  some  aspergillus  or  streptothrix,  and  more  rarely  by 
nematodes;  but  in  either  case  grey  nodules  and  caseating 
tubercles  present  appearances  very  liable  to  be  mistaken  for 
tuberculosis,  both  in  quadrupeds  and  birds.  A  Bacillus  pseudo- 
tuberculosis was  isolated  by  Pfeiffer  from  some  of  these  cases, 
and  more  recently  Klein  has  found  the  same  bacillus  in  water, 
milk,  sewage  and  sewage  effluents.  It  is  pathogenic  for  animals, 
producing  lesions  like  the  Bacillus  tuberc^dosis,  but  no  giant  cells 
are  found  in  them.  Animals  are  killed  by  it  sooner  than  by  the 
tubercle  bacillus.  The  disease  known  as  actinomycosis  is  some- 
times mistaken  for  tuberculosis,  and  vice  versa. 

The  preventive  measures  which  may  be  taken  to  reduce 
tuberculosis  may  be  summarized  as— 

I.  The  compulsory  notification  of  phthisis,  as  now  required 
under  the  Public  Health  (Tuberculosis)  Regulations,  1912 
(see  p.  488). 

The  notified  case  should  be  visited  by  the  Medical  Officer  of 
Health,  or  someone  acting  on  his  behalf.  A  careful  note  should 
be  made  of  the  home  conditions,  and  the  patient  should  be  in- 
structed in  proper  methods  of  collecting  and  disposing  of  the 
sputum.  The  patient  should  be  urged  to  sleep  in  a  room  by 
himself,  or  at  any  rate  in  a  separate  bed,  and  to  maintain  a  good 
state  of  ventilation,  by  keeping  the  window  of  his  day-room  and 
sleeping-room  always  open.  Advice  should  be  given  as  to  diet, 
clothing,  protection  from  chills  and  exposure,  and,  if  the  patient 
remains  at  work,  how  to  obviate  any  risk  of  infecting  fellow- 
workmen.  At  the  same  time,  other  members  of  the  patient's 
family  and  "  contacts  "  in  the  same  house  should  be  seen,  and, 
if  necessary,  their  state  of  health  should  be  inquired  into.  "  Sus- 
pects "  should  be  sent  to  the  local  tuberculosis  dispensary  to 
undergo  a  thorough  medical  examination. 

The  patient,  if  an  insured  person  under  the  National  Insurance 
Act,  should  be  advised  as  to  how  to  obtain  sanatorium  benefit 
from  the  Insurance  Committee;  and  where  sanatorium  benefit 
has  been  made  available  for  non-insured  persons,  the  patient, 
if  non-insured,  and  not  already  receiving  medical  attention, 
should  be  urged  to  seek  advice  and  treatment  at  the  local  tuber- 
culosis dispensary. 


COMMUNICABLE    DISEASES  485 

2.  The  removal  of  those  conditions  of  domicile  and  of  occupa- 
tion which  are  known  to  promote  the  incidence  of  the  disease, 
including  the  regulation  of  certain  dusty  trades. 

3.  The  diffusion  of  knowledge  (by  medical  men,  leaflets,  etc.), 
regarding  the  nature  and  modes  of  spread  of  the  disease,  and  the 
precautions  which  should  be  taken  in  order  to  prevent  its  ex- 
tension. 

A  continuous  supply  of  fresli  air,  admilted  through  the  window,  can  be 
tolerated  night  and  da}'  if  either  of  the  following  arrangements  is  made: 

(a)  Raise  the  lower  sash  of  the  window  for  6  inches,  and  then  closely 
fit,  into  the  open  space  below,  a  wooden  board.  Air  then  enters  where 
the  upper  and  lower  sashes  overlap,  without  causing  a  draught. 

ih)  Open  the  window  at  the  top  for  6  inches  and  fix  a  mvislin  curtain, 
or  nail  a  piece  of  muslin,  so  that  it  covers  the  open  part.  By  this  device 
draughts  are  very  much  reduced. 

(c)  A  screen  reaching  to  a  little  above  the  head  of  the  sufferer  can  be 
placed  alongside  the  upper  part  cf  the  bed,  on  the  window  side.  No 
draught  will  then  be  felt  by  the  sufferer. 

4.  The  testing  of  sputum  and  other  suspected  discharges,  and 
of  milk,  meat,  etc.,  supposed  to  be  tuberculous,  by  the  sanitary 
authority  free  of  charge. 

5.  Local  authorities  to  undertake,  without  charge,  the  dis- 
infection of  houses  recently  occupied  by  phthisical  persons. 

6.  The  establishment  of  sanatoria  and  isolation  accommoda- 
tion for  the  cure  of  phthisical  patients,  and  the  isolation  of  those 
who  are  a  distinct  source  of  danger  to  fellow  lodgers  or  workers. 
Newsholme  has  pointed  out  that  the  death-rate  from  phthisis 
has  declined  to  the  greatest  extent  in  those  countries  in  which 
the  ratio  of  institutional  to  domestic  relief  has  been  highest; 
and  that  the  admissions  to  workhouse  infirmaries,  hospitals, 
and  lunatic  asylums  have  greatl}^  increased  in  this  coimtry  during 
the  past  thirty-five  years. 

7.  The  enforcement  of  measures  against  spitting  in  public 
conveyances  and  in  places  of  public  resort. 

8.  The  efficient  sanitary  supervision  of  dairy  farms,  dairies, 
and  milkshops.  The  periodical  veterinary  inspection  and 
testing  (by  tuberculin)  of  milch  cows,  and  the  removal  of  tuber- 
culous animals  from  the  herd.  The  prohibition  of  the  sale  of 
milk  of  cows  affected  with  tuberculosis. 

9.  The  proper  inspection  of  meat  in  public  abattoirs,  and  the 
adoption  of  due  precautions  for  the  control  of  imported  meat  and 
milk. 


ij86  HYGIENE    AND   PUBLIC   HEALTH 


Sanatoria  for  Consumptives. 

Although  there  has  been  a  tendency  to  exaggerate  the  good  results  to 
be  derived  from  the  sanatorium  treatment  of  consumption,  the  value  of 
the  treatment  is  very  considerable  and  has  been  abundantly  testified  to, 
more  particularly  in  Germany,  where  more  than  a  hundred  sanatoria 
exist.  But  it  is  necessary  to  make  a  careful  selection  of  the  cases  to  be 
admitted,  if  the  best  results  are  to  be  obtained  from  the  expenditure 
entailed.  Cases  of  recent  origin  with  limited  lesions  and  little  or  no  fever 
may  be  expected  to  derive  considerable  benefit  from  the  sanatorium  treat- 
ment, but  a  carefully  selected  chronic  case  may  be  found  to  benefit  also, 
sometimes  more  so  than  some  of  the  early  and  acute  cases.  Another 
necessary  condition  of  success  is  the  retention  of  the  patient  for  a  suffi- 
ciently long  period  (six  months,  on  the  average)  before  he  is  discharged, 
and  even  then  regard  must  be  had  to  the  fact  that  he  is  very  liable  at  any 
time  to  a  relapse.  With  the  view  of  reducing  this  risk  it  is  often  necessary 
that  the  individual  should  not  return  to  his  old  occupation  and  environ- 
ment; and,  therefore,  it  seems  desirable  in  connection  with  such  institu- 
tions that  there  should  be  an  After-Care  Committee,  whose  duty  should  be 
to  keep  in  touch  with  the  discharged  individual,  to  advise  him,  and  (where 
necessary  and  possible)  assist  him  in  obtaining  suitable  outdoor  occupation. 
Failure  to  comply  with  the  above  provisions  may  result  in  the  sanatorium 
treatment  proving  a  costly  failure. 

The  general  features  of  the  sanatorium  treatment  are  as  follows:  As 
much  as  possible  of  the  life  of  the  patient  is  spent  in  the  open  air  ;  at 
certain  stages  absolute  rest  is  required,  at  others  graduated  exercise; 
careful  and  generous  feeding  is  an  important  part  of  the  treatment;  mas- 
sage, baths,  and  cold  sponging  are  also  necessary  for  certain  cases;  and  the 
educational  and  disciplinary  effects  should  be  such  as  to  continue  of  lasting 
value  to  the  patients.  It  is  necessary  that  the  patients  should  be  under 
almost  constant  medical  supervision;  they  should  be  carefully  classified, 
and  most  of  them  should  be  visited  three  times  daily,  the  temperature 
taken  and  directions  given  with  reference  to  food,  exercise,  etc.,  in  accor 
dance  with  their  condition.  Therefore  there  should  be  one  medical  man 
to  not  more  than  forty  patients.  It  is  furthermore  desirable  in  connec- 
tion with  such  institutions  that  there  should  be  provision  in  the  grounds 
for  some  kind  of  labour,  especially  when  the  sanatorium  is  a  poor-class 
one.  The  employment  of  suitable  patients  in  a  little  gardening,  poultry 
farming,  bee-keeping,  or  other  light  labour,  not  only  does  something  to 
prevent  them  from  becoming  lazy,  but  serves  to  train  them  in  outdoor 
pursuits,  and  this  training  they  can  sometimes  turn  to  account  after 
leaving  the  sanatorium.  At  the  Frimley  Sanatorium  of  the  Brompton 
Hospital  for  Consumption,  the  Resident  Medical  Officer,  Dr.  Patterson, 
has  introduced  a  system  of  graduated  labour,  by  which  patients  can  be 
led  on,  stage  by  stage,  to  undertake  the  most  laborious  forms  of  manual 
work  such  as  is  ordinarily  performed  by  navvies.  This  graduated  system 
of  labour  has  been  found  to  have  an  important  influence  on  treatment  and 
cure  of  the  disease,  the  effect  of  the  graduated  exercise  being  to  cause  auto- 
inoculation — that  is  to  say,  the  tubercular  toxins,  as  the  result  of  exercise, 
are  introduced  into  the  systemic  circulation,  and  tend  to  raise  the  resisting 
power  of  the  individual,  in  the  same  way  as  do  inoculations  of  dead  bacilli 
and  their  products  in  "  vaccine  treatment." 

The  site  of  a  sanatorium  is  a  matter  of  prime  importance.  The  ideal 
site  is  the  southern  slope  of  a  hill,  sheltered  from  the  north  and  east  winds 


COMMUNICABLE    DISEASES  487 

by  rising  ground  or  trees.  There  should  be  a  wide  clearing  of  any  trees  on 
the  south  side,  and  to  a  less  degree  on  the  other  aspects.  The  aim  is  to 
obtain  a  site  with  pure  air,  abundant  sunshine,  clean  and  dry  soil,  a  low 
but  equable  temperature,  and  protected  from  winds.  The  site  should  b;- 
of  easy  access,  not  too  far  from  a  railway  station,  and  well  away  from  a 
high  road  and  the  dust  which  may  arise  from  it.  For  an  institution  of 
ICO  beds  it  is  desirable  to  have  100  acres  of  land,  in  order  that  there  may 
be  sufficient  ground  to  provide  protected  walks  for  the  patients,  for  keeping 
cows,  for  growing  vegetables,  and  for  providing  work  for  convalescents. 
Dotted  about  the  grounds  there  should  be  a  large  number  of  seats.  Prob- 
ably mo  beds  are  sufficient  for  any  one  institution;  and  not  more  than 
six  beds  should  be  placed  in  one  ward.  In  the  more  expensive  sanatoria 
a  large  proportion  of  the  bedrooms  are  single  bedrooms,  which  is  of  course 
an  ideal  arrangement.  The  ideal  sanatorium  consists  of  a  number  of 
isolated  chalets  surrounding  the  central  administrative  block,  each  chalet 
to  accommodate  one  patient.  The  chalet  need  be  only  of  the  size  of  a 
small  room,  with  an  added  verandah.  It  should  be  raised  from  the  ground 
and  provided  with  windows  in  all  four  directions.  A  very  good  arrange- 
ment is  to  have  two-thirds  of  the  accommodation  provided  in  chalets, 
and  the  remainder  in  one  main  building.  The  main  building  should  have 
balconies  with  verandahs  and  French  windows,  so  that  the  beds  may  be 
wheeled  out  on  to  balconies,  and  bedrooms  of  at  least  1,500  cubic  feet 
capacity,  with  floors  made  of  teak  or  oak  on  cement  concrete.  The  linoleum 
frequently  used  in  Germany  and  elsewhere  to  cover  the  floors  is  not  satis- 
factory. Washable  distemper  walls  with  a  smooth  surface  are  desirable; 
the  lighting  should  be  by  electricity,  and  the  warming  by  hot  water  pipes. 
Electric  fans  for  ventilation  are  sometimes  desirable  in  winter. 

In  a  Memorandum  of  the  Local  Government  Board  (191 3)  it  is  recom- 
mended that  in  the  construction  of  inexpensive  buildings  for  sanatorium 
purposes  the  following  materials  may  be  employed:  Timber-framing, 
weather-boarded  and  creosoted,  or  covered  with  corrugated  iron  or  other 
suitable  material,  such  as  asbestos  sheeting,  and  lined  internally  with 
lath  and  plaster,  asbestic  sheeting,  etc.  These  may  be  erected  on  a  con- 
crete platform,  which  may  also  form  the  flooring  of  the  wards  and  ver- 
andahs, the  floors  to  be  finished  in  cement  and  covered  with  linoleum. 

In  connection  with  a  sanatorium  provision  must  be  made  for  disin 
fecting  and  incinerating  infected  material,  and  a  dispensary,  pathological 
laboratory,  consulting-room,  mortuary  and  post-mortem  room,  laundry 
and  drying-rocm,  baths,  operating  theatre,  library,  committee-room, 
recreation  room,  private  dairy,  ambulance,  and  electrical  engine-house 
have  all  to  be  provided.  It  will  be  seen,  therefore,  that  a  sanatorium  is 
of  necessity  an  expensive  provision;  but  all  arrangements  for  the  treatment 
can  be  made  on  quite  a  satisfactory  basis  at  a  cost  of  from  ;^ioo  to  ^200  a 
bed,  and  there  is  no  occasion  to  spend  the  very  large  amounts  which  have 
often  been  spent  on  costly  structures  in  this  country. 

The  Anti-Tuberculosis  Dispensary  is  an  important  provision  in 
the  campaign  against  tuberculosis.  Such  a  dispensary  should  be 
in  effective  touch  with  the  homes  of  the  sufferers,  and  should 
be  linked  up  with  the  Municipal  Pubhc  Health  Department,  a 
sanatorium,  a  hospital  for  advanced  cases,  and  an  after-care 
association.  It  should  be  central,  and  constitute  itself  a  bureau 
of  information  upon  the  disease,  and  a  link  with  all  institu- 


488  HYGIENE    AND    PUBLIC   HEALTH 

tions  and  local  provisions  for  dealing  with  infected  persons.  It 
must  provide  nurses  and  health  workers  to  visit  the  homes  and 
to  instruct  the  occupants,  and  supply  the  means  for  the  bac- 
teriological examination  of  sputum ;  it  should  dispense  necessary 
medicines,  sputum  bottles,  disinfectants,  and,  where  the  patient's 
condition  seems  to  warrant  it,  even  foodstuffs  and  articles  of 
clothing.  It  should  therefore  enlist  the  support  of  local  charitable 
organizations. 

The  Public  Health  {Tuberculosis)  Regulations,  191 2. 

These  are  Regulations  made  by  the  Local  Government  Board  imder 
the  powers  conferred  by  Section  130  of  the  Public  Health  Act,  1875.  as 
amended  by  the  Public  Health  Act,  1 896. 

Every  Local  Authority  is  required  to  provide  forms  for  notification  as 
set  out  in  Schedule  A  of  the  Regulations,  and  to  supply  them  to  the 
medical  practitioners  within  its  district.  Every  medical  practitioner 
shall,  within  forty-eight  hours  after  first  becoming  aware  that  a  person 
whom  he  is  attending  is  suffering  from  tuberculosis,  notify  (Form  A) 
the  Medical  Officer  of  Health  for  the  district  within  which  the  place  of 
residence  of  the  person  is  situate  at  the  date  of  notification.  A  medical 
practitioner  is  not  required  to  notify,  if  he  has  reasonable  grounds  for 
believing  that  the  case  has  been  already  notified  under  the  existing  or 
previous  Regulations.  Where  the  person  is  an  in-patient  at  an  institu- 
tion, the  notification  must  be  sent  to  the  Medical  Officer  of  Health  of  tlfe 
district  in  which  the  usual  place  of  residence  of  the  patient  is  situate. 
Every  school  medical  inspector  must  notify  (Form  B)  at  the  end  of  each 
week  all  cases  of  tuberculosis  of  which  he  has  just  become  aware,  in  the 
course  of  inspections  made  by  him  during  the  week,  of  children  attending 
public  elementary  schools.  The  notifications  are  to  be  sent  to  the  Medical 
Officer  of  Health  of  the  district  within  which  the  places  of  residence  of 
the  children  are  situate.  The  medical  officer  of  a  Poor-Law  institution 
or  of  a  sanatorium,  in  addition  to  being  required  to  notify  new  cases 
(Form  A),  must  also  notify  weekly  (Form  C)  all  cases  of  tuberculosis 
admitted  during  the  week,  which  have  been  previously  notified,  to  the 
Medical  Officer  of  Health  of  the  district  within  which  the  places  of  residence 
of  the  persons  notified  are  situate;  and  under  Form  D  he  must  notify  all 
cases  of  tuberculosis  discharged  during  the  week,  other  than  cases  trans- 
ferred to  a  Poor-Law  institution  or  a  sanatorium,  to  the  Medical  Officer  of 
Health  for  the  district  within  which  the  places  of  destination  of  the  persons 
notified  are  situate. 

The  diagnosis  of  tuberculosis  must  not  be  based  solelj'  on  the  results 
of  tuberculin  tests. 

The  fees  for  notification  are  chargeable  quarterly  to  the  Local  Authority 
for  the  district  within  which  the  place  of  residence  or  place  of  destination 
of  the  person  notified  is  situate.  The  fees  for  Form  A  are  2s.  6d.  to  a 
private  practitioner,  and  is.  to  the  medical  officer  of  a  hospital,  of  a 
Poor-Law  institution,  or  a  District  Medical  Officer.  For  forms  C  and  D 
the  medical  officer  of  a  Poor-Law  institution  is  entitled  to  is.  for  the  first 
name  on  each  list,  and  to  3d.  for  each  additional  name.  School  medical 
officers  and  medical  officers  of  sanatoria  receive  no  remuneration  for 
notifying. 

All  notifications  and  documents  as  to  notified  persons  are  to  be  regarded 


COMMUNICABLE    DISEASES  4^9 

as  confidential.  The  Medical  Officer  of  Health  is  required  to  forw^ard 
on  notifications  of  persons  not  residing  in  his  own  district,  to  keep  a  register 
of  all  cases  in  his  district,  and  to  forward  a  weekly  list  to  the  Medical  Officer 
of  Health  of  the  county.  The  Medical  Officer  of  Health,  or  an  officer 
acting  under  his  instructions,  shall  make  such  inquiries  and  take  such 
steps  as  are  necessary  or  desirable  for  investigating  the  source  of  infection, 
for  preventing  the  spread  of  infection,  and  for  removing  conditions  favour- 
able to  infection.  A  Local  Authority,  on  the  advice  of  their  Medical  Officer 
of  Health,  may  supply  all  such  medical  or  other  assistance,  and  all  such 
facilities  and  articles  as  may  reasonably  be  required  for  the  detection 
of  tuberculosis,  for  preventing  the  spread  of  infection,  and  for  removing 
conditions  favourable  to  infection;  and  for  that  purpose  may  appoint 
such  officers,  do  such  acts,  and  make  such  arrangements,  as  may  be 
necessary.  The  Local  Authority  may  also  provide  and  publish  or  dis 
tribute  suitable  summaries  of  information  and  instruction  respecting 
tuberculosis  and  the  precautions  to  be  taken  against  the  spread  of  tuber- 
cular infection. 

Nothing  is  to  be  done  under  the  Regulations  which  renders  the  notified 
person,  or  anyone  in  charge  of  such  person,  or  any  other  person,  liable  to 
a  penalty,  or  subjects  the  notified  person  to  any  restriction,  prohibition, 
or  disability  affecting  himself  or  his  employment,  occupation  or  means  of 
livelihood,  on  the  ground  of  his  suffering  from  tuberculosis. 

The  penalty  for  a  contravention  of  the  Regulations  is  a  fine  not  exceeding 
;^ioo,  and,  in  the  case  of  a  continuing  offence,  a  further  penalty  not  ex- 
ceeding ^50  for  every  day  during  which  the  offence  continues  [Public 
Health  Act,  1896,  Section  i  (3)]. 

The  National  Insurance  Act,  1911. 

Under  this  Act  "  insured  persons  "  who  are  suffering  from  tuberculosis, 
in  addition  to  the  other  benefits  provided  for  in  the  Act  (medical,  sickness, 
and  disablement),  are  entitled  to  receive  sanatorium  benefit,  which  is 
defined  as  being  "  treatment  in  sanatoria  or  other  institutions  or  other- 
wise." By  Section  16,  for  the  purpose  of  administering  sanatorium  benefit. 
Insurance  Committees  shall  make  arrangements,  to  the  satisfaction  of  the 
Insurance  Commissioners,  for  providing  treatment  for  insured  persons 
suffering  from  tuberculosis  in  sanatoria  and  other  institutions  (hospitals, 
convalescent  homes,  homes  of  rest,  etc.)  with  persons  or  Local  Authorities 
(other  than  Poor-Law)  having  the  management  of  such  sanatoria  or 
institutions,  which  are  to  be  approved  by  the  Local  Government  Board. 
Treatment  may  also  be  given  otherwise  than  in  sanatoria  or  institutions 
by  means  of  dispensaries  or  by  medical  practitioners  in  a  manner  approved 
by  the  Local  Government  Board.  For  defraying  the  expenses  of  sana- 
torium benefit  the  annual  sum  of  is.  3d.  for  each  insured  person  resident 
in  the  county  or  county  borough  is  set  aside  out  of  the  funds  accruing 
under  the  Act,  and  the  sum  of  id.  in  respect  of  each  such  person  out  of 
money  provided  by  Parliament.  But  the  latter  amount  may  be  retained  in 
whole  or  in  part  by  the  Insurance  Commissioners  for  the  purposes  of  research. 

Out  of  the  IS.  3d.  available  annually  the  sum  of  6d.  has  been  allotted 
for  the  purpose  of  payment  to  medical  practitioners  on  the  "  panel," 
who  attend  and  treat  insured  persons  suffering  from  tuberculosis  in  their 
own  homes,  so  that  the  sum  of  gA.  remains  for  the  purposes  of  sanatorium 
and  other  institutional  treatment  (hospitals,  dispensaries,  hemes  of  rest, 
etc.).  An  insured  person  is  not  entitled  to  sanatorium  benefit  unless 
recommended  for  such  by  the  Insurance  Committee. 


490  HYGIENE    AND    PUBLIC   HEALTH 

The  Insurance  Committee  for  any  county  or  count}'  borough  may 
extend  sanatormm  benefit  to  the  dependents  of  insured  persons,  or  to 
any  class  of  such  dependents.  By  Section  17  (2),  if  in  any  year  the  amount 
available  for  defraying  the  expenses  of  sanatorium  benefit  is  insufficient 
to  meet  the  estimated  expenditure,  the  Insurance  Committee  mav  trans 
mit  to  the  Treasury  and  the  County  Council  or  County  Borough  Council 
a  statement  of  accounts,  and  the  latter  bodies  may  sanction  the  expen- 
diture, and  will  then  be  liable  to  make  good  (Treasury  one-half.  County 
Council  or  County  Borough  Council  one-half)  the  expenditure  on  sana- 
torium benefits  in  excess  of  what  is  available  from  the  funds  of  the  Insur- 
ance Committee.  The  above  section  applies  to  the  treatment  of  insured 
persons  and  their  dependents;  but  the  Government  has  decided  that 
money  shall  be  available  from  the  Treasury  Grant  for  the  treatment  in 
addition  of  non-insured  persons,  as  if  they  had  been  included  in  Section  17. 
By  Section  22,  the  Council  of  any  borough  or  urban  or  rural  district 
may  agree  with  the  County  Council  to  repay  to  the  latter  body  the  whole 
or  any  part  of  the  money  payable  by  the  Council  in  accordance  with  the 
provisions  of  Section  17,  so  far  as  tliat  money  has  been  or  will  be  expended 
on  medical  or  sanatorium  benefits  for  the  inhabitants  of  the  borough  or 
urban  or  rural  district. 

Section  64  (i)  of  the  National  Insurance  Act  taken  with  Section  16 
(i)  (f>)  of  the  Finance  Act,  191 1,  makes  available  frcnr  the  National 
Treasury  a  sum  of  ;^i, 500,000  for  the  purpose  of  the  provision  of  and 
making  grants  in  aid  to  sanatoria  and  other  institutions  in  the  United 
Kingdom. 

A  Departmental  Committee  was  appointed  by  the  Government  in  191 2 
to  consider  and  report  upon  the  problem  of  tuberculosis  in  the  United 
Kingdom  in  its  preventive,  curative,  and  other  aspects,  so  as  to  guide 
the  Government  and  local  bodies  in  making  or  aiding  provision  for  the 
treatment  of  tuberculosis  in  sanatoria  or  other  institutions  or  otherwise. 
The  Committee  recommended  the  establishment  of  tuberculosis  dis- 
pensaries, the  intention  being  that  each  dispensary  should  be  the  local 
centre  of  expert  diagnosis  and  treatment  acting  in  co-operation  with  the 
private  practitioners  of  the  district.  The  dispensary  would  also  serve 
as  a  clearing-house  through  which  all  persons  suffering  from  tuberculosis 
should  be  passed ;  and  it  should  have  important  functions  as  a  centre 
for  the  examination  of  "  contacts,"  the  "  after-care  "  of  patients  dis- 
charged from  institutions,  and  for  the  dissemination  of  information  with 
regard  to  tuberculosis. 

The  Committee  were  of  opinion  that  one  dispensary  would  be  required 
for  every  150,000  to  200,000  of  the  population  in  urban  districts,  but  that 
in  rural  districts  only  a  smaller  number  of  jiersons  could  be  served.  They 
recommended  that  capital  grants  from  the  Treasury  should  be  made  up 
to  four-fifths  of  the  amount  required  for  the  provision  and  equipment 
of  dispensaries,  provided  that  this  sum  should,  generally,  not  exceed  £1 
per  750  population,  or  an  average  of  /240  per  dispensary.  With  regard 
to  sanatoria,  the  Committee  considered  that  most  probably  one  sanatorium 
bed  per  5,000  population  would  be  required  for  the  United  Kingdom,  and 
the  same  proportion  for  the  purposes  of  observation,  training,  and  isolation, 
and  that  in  the  interests  of  economy,  an  individual  sanatorium  should 
not  contain  less  than  100  beds.  They  recommended  that  capital  grants 
from  the  Treasury  up  to  three-fifths  of  the  cost  per  bed  (estimated  at  not 
exceeding  £150)  should  be  made  for  the  provision  of  additional  sanatorium 
and  hospital  beds  for  adults,  provided  that  the  total  sum  should  not 
exceed  £go  per  bed. 


COMMUNICABLE    DISEASES  491 

The  recommendations  of  the  Committee  with  regard  to  the  grants  of 
money  from  tlie  Treasury  have  been  adopted  by  the  Government. 

The  two  Reports  of  the  Committee  enter  very  fully  into  the  various 
questions  connected  with  the  functions  of  tuberculosis  dispensaries,  the 
accommodation  to  be  provided,  the  staffing  (including  the  appointment 
of  tuberculosis  officers),  the  cost,  etc.  The  provision  and  administration 
of  sanatoria,  hospitals,  and  other  institutions  for  dealing  with  all  varieties 
of  tubercular  disease  are  considered  and  described,  together  with  the 
methods  of  prevention  suitalMe  for  dealing  with  the  disease  as  arising  from 
food,  infection  by  tuberculous  persons,  etc.  For  the  purpose  of  securing 
the  proper  organization  of  comprehensive,  efficient,  and  economical  schemes, 
it  is  recommended  by  the  Committee  that  the  administrative  area  should 
generally  be  that  of  a  county  or  county  borough,  or,  in  some  cases,  a  group 
of  counties  and  county  boroughs. 

Epiacmic  [n/Inen::a. 

Influenza  in  its  epidemic  form  is  an  infectious  disease,  and 
sl-iould  be  classed  with  specific  fevers.  Nothing  very  definite 
is  known  of  the  etiology  of  influenza,  but  it  does  not  appear  to 
show  a  perference  for  any  particular  localities,  nor  to  follow  always 
the  same  channels  of  communication,  and  it  has  prevailed  in- 
dependently of  season,  climate,  and  weather.  The  disease  does 
not  seem  to  associate  itself  especially  with  insanitary  surround- 
ings, and  the  incidence  upon  the  poor  is  generally  fighter  than 
upon  the  better  class  of  the  population. 

Although  now  regarded  as  infectious,  and  propagated  mainly 
by  human  intercourse,  it  was  at  first  supposed  that  influenza 
was  spread  chiefly  by  an  air-borne  miasm,  and  not  by  personal 
infection  or  fomites  in  the  ordinary  way.  The  facts  relied  upon 
were  the  rapidity  of  spread  of  the  epidemic,  and  the  supposed 
simultaneity  of  outbreak  upon  large  numbers  of  people.  But 
it  is  now  recognized  that  the  rapidity  of  spread  is  not  greater 
than  that  of  human  intercourse  with  modern  faci'ities  of  travel, 
and  that  scattered  cases  usually  precede  the  general  onset  of 
the  epidemic  upon  a  community.  The  epidemic,  moreover, 
has  often  been  observed  to  travel  in  directions  opposed  to  the 
prevailing  winds,  and  to  be  independent  of  any  particular  kind  of 
weather.  There  can  be  no  doubt  that  those  engaged  in  out- 
door occupations  are  often  first  attacked,  but  such  people — 
especially  postmen  and  policemen — may  be  exposed  to  con- 
tagion before  the  rest  of  the  population.  Equine  influenza 
occasionally  precedes  the  human  disease  in  its  epidemic  form, 
but  it  is  doubtful  if  the  maladies  as  seen  in  animals  and  men 
are  really  identical,  i  e.,  dependent  upon  a  common  cause. 

The  chief  arguments  in  favour  of  personal  communicability 


492  HYGIENE    AND    PUBLIC   HEALTH 

are: — (i)  The  very  frequent  occurrence  of  cases  in  succession 
in  the  same  household.  (2)  In  many  instances  the  first  case  in 
a  household  or  neighbourhood  can  be  traced  to  exposure  to 
infection  from  a  previous  case,  or  to  a  visit  to  an  infected  locality. 

(3)  The  special  incidence  of  the  disease  upon  persons  liable  to 
come  into  contact  with  infection — e.g.,  medical  men  and  nurses. 

(4)  Persons  living  under  circumstances  in  which  the  possibility 
of  infection  can  be  excluded  (prisoners  in  gaols,  sailors  at  sea, 
lighthouse  keepers)  have  escaped  influenza  altogether.  (5)  That, 
as  a  general  rule,  in  each  country  it  has  appeared  first  in  the 
capital  or  ports  of  entry,  and  the  towns  have  been  infected  earlier 
than  country  places.  (6)  That  neighbouring  communities  have 
in  certain  instances  been  affected  at  considerably  different  dates. 

The  sudden,  almost  simultaneous,  attacks  of  large  numbers 
of  people,  following  upon  the  appearance  of  a  few  scattered  cases, 
is  accounted  for  by  the  very  general  susceptibility  to  the  disease, 
and  its  short  incubation  period. 

There  is  considerable  evidence  in  favour  of  the  bacillus  of 
Pfeiffer,  Kitasato,  and  Canon  being  the  specific  organism  of 
influenza,  it  being  found  in  almost  pure  cultures  in  the  bronchial 
secretions  of  influenza  cases,  but  not  in  other  allied  diseases. 

As  regards  age  and  sex  incidence,  those  in  the  middle  periods 
of  life  (twenty  to  sixty  years)  are  most  attacked;  people  over 
sixty  come  next,  and  children  least.  Males  at  all  ages  are 
more  liable  to  attack  and  to  severe  illness  than  females.  All 
depressing  influences,  chills,  and  fatigue  are  said  to  favour  the 
development  of  the  disease;  but  vigorous  health  is  no  pre- 
ventative, and  no  guarantee  that  the  malady  will  assume  a  mild 
type.  The  incubation  period  is  usually  between  two  and  four 
days,  but  may  be  only  one  day,  or  may  extend  to  five.  The 
average  duration  of  an  attack  is  ten  days.  The  duration  of 
infectiveness  is  not  certainly  known,  but  may  continue  into 
the  stage  of  convalescence.  One  attack  is  not  protective,  and 
relapses  are  frequent. 

Three  types  of  the  disease  are  known,  in  which  the  respirator}' 
organs,  the  alimentary  system,  and  the  nervous  system  are, 
respectively,  most  affected.  In  different  epidemics  one  or  other 
of  these  types  may  prevail  more  extensively  than  the  others. 

During  an  epidemic  the  direct  mortality  from  influenza  as  a 
primary  cause  of  death  may  not  be  more  than  05  per  1,000; 
but  if  to  this  death-rate  we  add  the  mortality  indirectly  due  to 


COMMUNICABLE   DISEASES  493 

influenza  (the  excess  of  deaths  from  pneumonia,  bronchitis,  and 
heart  diseases  over  the  average  of  non-influenza  years),  the  death- 
rate  from  this  disease  and  its  after  consequences  is  not  far  short 
of  2  per  1,000,  or  nearly  equal  to  the  total  zymotic  death-rate 
now  recorded  in  many  large  towns.  During  the  past  five  years 
epidemics  have  prevailed  in  various  parts  of  the  country,  but 
the  resulting  mortality  has  been  much  less  than  in  the  first  five 
years  of  the  appearance  of  the  disease,  subsequent  to  1890. 

About  50  per  cent,  of  the  deaths  from  influenza  are  of  persons 
aged  sixty  and  upwards. 

As  regards  prevention,  theoretically,  notification  of  cases, 
isolation  of  the  sick,  disinfection  of  premises,  and  disinfection 
of  the  excretions,  especially  of  the  sputum  and  of  soiled  linen, 
should  be,  as  for  other  infectious  diseases,  the  proper  means  of 
checking  or  stamping  out  an  epidemic.  But  such  measures 
are  really  impracticable  for  general  adoption,  owing  (i)  to  the 
difficulty  of  making  an  exact  diagnosis  in  the  early  stages  of  an 
epidemic,  or  of  mild  cases  at  any  time;  (2)  to  the  wide  and  rapid 
diffusion  of  the  infection,  and  to  the  fact  that  the  wage-earning 
periods  of  life  are  most  affected  (the  movements  of  adults  being 
far  more  difficult  to  control  than  those  of  children) ;  and  (3)  to 
the  impossibility  under  the  circumstances  of  treating  influenza 
as  a  dangerous  infectious  disease,  and  inflicting  a  penalty  upon 
those  found  exposing  themselves  in  public  places.  An  effort, 
however,  should  always  be  made  to  promptly  isolate  the  first 
case  occurring  in  a  house  or  institution  and  to  carefully  disinfect 
the  sputum;  and  while  the  disease  is  prevalent  it  is  well  to  avoid 
exposure  to  cold  and  fatigue,  to  clothe  the  body  warmly,  to 
avoid  indulgence  in  excess  of  alcohol,  and  not  to  visit  places 
to  which  large  numbers  of  the  public  resort. 

In  the  early  autumn  of  1904  an  epidemic,  which  presented 
some  unusual  features  and  embraced  162  cases,  occurred  in 
Hertfordshire,  the  main  features  of  which  were  subsequently 
described  by  Dr.  R.  A.  Dunn,  whose  attention  was  first  drawn 
to  several  cases  of  apparent  influenza  in  members  of  a  single 
family,  where  one  member  developed  symptoms  of  scarlet  fever 
and  another  those  of  cerebro-spinal  irritation.  Some  of  the 
cases  in  this  Hertford  epidemic  were  bacteriologically  investigated 
by  Dr.  Gordon,  who  found  that  the  common  causal  factor 
appeared  to  be  the  micrococcus  catarrhalis.  The  outbreak 
differed  bacteriologically,  and  in  some  respects  epidemiologically 


494  HYGIENE   AND    PUBLIC   HEALTH 

and  clinically,  from  scarlet  fever,  cerebro-spinal  meningitis, 
influenza  or  rotheln,  and  its  hybrid  qualities  are  interesting  and 
significant. 

Contagious  Ophthalmia. 

There  are  two  kinds  of  contagious  eye  disease:  the  grey 
granulation  (trachoma)  and  purulent  conjunctivitis;  the  former 
appearing  to  predispose  the  sufferer  to  take  the  latter.  These 
diseases  are  not  uncommon  in  industrial  schools  and  barracks 
which  are  badly  ventilated,  and  where  the  inmates  are  not 
supplied  with  separate  basins  and  towels  for  ablution.  They 
are  chiefly  transmitted  from  the  sick  by  inoculation  of  the  eyes 
of  the  healthy  with  the  secretions  and  discharges  left  on  bed 
linen  and  towels;  but  it  is  also  probable  that  the  contagion  is 
carried  through  the  air  in  dried  epithelial  or  pus  cells. 

The  ophthalmia  caused  by  gonorrhoeal  infection  of  the  eyes, 
and  the  opthalmia  neonatorum,  inoculated  from  purulent  vaginal 
discharge,  are  especially  virulent  and  destructive  forms  of  eye 
disease.  Ophthalmia  neonatorum  is  productive  of  about  one- 
tenth  of  all  cases  of  blindness,  and  of  at  least  one-third  of  the 
blindness  in  inmates  of  British  bhnd  schools.  One  of  the  rules 
issued  by  the  Central  Midwives  Board  is  to  the  effect  that, 
"  As  soon  as  the  child's  head  is  born,  and,  if  possible,  before  the 
eyes  are  opened,  its  eyelids  should  be  carefully  cleansed,"  with 
clean,  lukewarm  water.  Moreover,  whenever  there  is  inflam- 
mation of  the  eyes,  however  sHght,  medical  help  must  be  sought. 
This  disease  has  been  made  compulsorily  notifiable  in  a  few 
districts.  In  all  forms  of  purulent  ophthalmia  a  pyogenic 
micro-organism — the  Staphylococcus  pyogenes  aureus  or  albus — 
is  usually  the  active  cause  of  the  disease. 

Cerebro-Spitial  Fever,  or  Epidemic  Cerebrospinal  Meningitis. 

The  specific  character  of  this  disease  is  now  generally  recog- 
nized, but  probably  some  cases  so  diagnosed  are  really  suffering 
from  tubercular  meningitis  or  meningitis  due  to  pneumococcus 
infection.^       Cerebro-spinal    meningitis    is    not    an    infrequent 

^  Sir  Thomas  Barlow  and  Dr.  I.ees  have  drawn  attention  to  a  form 
of  meningitis  in  children,  which  is  now  known  as  posterior  (non-tuber- 
culous) basic  meningitis — due  to  a  diplococcus  closely  allied  to  the  diplo- 
coccus  of  Weichselbaum,  found  in  epidemic  cerebro-spinal  meningitis. 
It  is  usually  held  now,  that  posterior  basic  meningitis  is  a  sporadic  form  of 
cerebro-spinal  meningitis.  It  appears  to  be  endemic  in  many  large  cities 
and  towns  in  this  country,  on  the  Continent,  and  in  America. 


COMMUNICABLE   DISEASES  495 

complication  of  many  febrile  diseases,  but  this  form  is  never 
epidemic  or  communicable;  nor  is  it  attended  by  the  purpura 
or  herpetic  eruptions  occasionally  characteristic  of  cerebro-spinal 
fever.  The  latter  is  also  distinguished  by  the  absence  of  any 
associated  disease.  Anomalous  forms  of  cerebro-spinal  fever 
have  been  mistaken  for  sunstroke  and  enteric  fever. 

The  disease  is  relatively  rare  in  this  country,  being  more 
prevalent  in  the  United  States  and  certain  localities  on  the 
continent  of  Europe,  and  is  probably  on  the  increase.  It  occurs 
more  in  winter  and  spring  than  in  the  warmer  months  of  the  year. 
An  organism  having  a  diplococcus  form  and  often  called  the 
meningococcus  {Diplococcus  meningitidis  intracellular  is  of  Weich- 
S3lbaum)  is  found  in  the  cerebro-spinal  fluid  in  the  polymorpho- 
nuclear cells  which  are  abundantly  present,  causing  the  fluid  to 
be  turbid.  Animals,  especially  horses  and  pigs,  are  probably 
also  liable  to  the  disease.  The  diplococcus  is  said  to  be  con- 
stantly present  in  the  nasal  discharge  of  the  sufferers,  and  not 
infrequently  in  the  nasal  secretions  of  those  in  attendance  upon 
the  sick;  and  the  disease  is  undoubtedly  spread  by  means  of 
"  contacts,"  and  mild,  unrecognized  or  abortive  cases.  The 
nasal  discharge  is  sometimes  so  profuse  as  to  cause  the  disease 
to  be  mistaken  for  influenza,  and  it  is  probably  the  main  channel 
of  infection,  but  the  infectivity  of  many  cases  appears  to  be 
exceedingly  slight.  Since,  however,  direct  personal  infection 
probably  plays  a  part  in  the  spread  of  the  disease,  it  is  well  to 
endeavour  to  isolate  the  sick,  and  to  apply  suitable  measures 
of  disinfection.  Overcrowding  and  bad  air  appear  to  predispose 
to  attack,  but  insanitary  environment  is  not  a  dominating  factor 
in  etiology.  The  disease  affects  children  and  young  people, 
sometimes  sporadically  and  often  in  epidemic  waves;  and  the 
case  mortality  is  generally  very  high — -often  50  and  sometimes 
reaching  80  per  cent.  The  diagnosis  can  be  confirmed  bacterio- 
logically  by  a  lumbar  puncture  (which  is  almost  painless)  below 
the  end  of  the  spinal  cord;  and  an  examination  for  the  diplo- 
coccus can  be  made  in  the  cerebro-spinal  fluid  so  obtained. 
Lumbar  puncture,  with  the  removal  of  about  30  c.c.  of  fluid,  is 
also  a  palliative  for  the  relief  of  symptoms,  whilst  antimeningo- 
coccus  serum  (obtained  from  horses  immunized  for  many  months 
with  strains  of  cocci  from  human  sources)  is  useful  as  a  curative 
measure. 


496  HYGIENE   AND  PUBLIC   HEALTH 

Acute  Poliomyelitis. 

This  disease  is  due  to  an  ultra-microscopic  organism,  which  is 
filtrable  through  porcelain.  It  probably  enters  the  body  through 
the  naso-pharyngeal  mucous  membrane,  and  causes  acute  local- 
ized inflammation  in  the  anterior  cornua  of  the  grey  matter  of  the 
spinal  cord,  resulting  in  degeneration  of  the  large  motor  cells  of 
the  cornua,  thus  giving  rise  to  partial  or  complete  paralysis  of 
various  groups  of  muscles  (arms  and  legs).  The  disease  occurs 
sporadically  and  in  epidemic  form,  the  latter  being  commonest 
in  summer  and  autumn.  A  majority  of  the  cases  occur  in  children 
under  six  years  of  age.  The  fatality  varies  in  different  epidemics 
from  6  to  30  per  cent. 

The  incubation  period  is  somewhat  uncertain,  but  is  often 
between  one  and  four  days.  The  disease  has  been  produced 
experimentally  in  monkeys  by  inoculating  them  with  an  emulsion 
from  the  nasal  mucous  membrane  or  the  submaxillary  lymphatic 
glands  of  a  human  case,  and  by  inhalation  of  the  virus,  or  by 
painting  it  on  the  nasal  mucous  membrane.  It  seems  probable, 
therefore,  that  the  disease  is  transmitted  in  man  from  person  to 
person  by  direct  contact,  in  the  same  way  as  diphtheria.  Trans- 
mission undoubtedly  occurs  through  healthy  "  carriers  "  and 
abortive  cases  without  characteristic  paralyses  or  severe  illness; 
such  abortive  cases  formed  15  per  cent,  of  the  total  cases  in  the 
Swedish  epidemic.  These  carriers  and  abortive  cases  probably 
are  more  instrumental  in  spreading  infection  than  the  serious 
acute  cases  with  recognizable  paralysis. 

Multiple  cases  occur  in  houses,  but  many  apparently  sus- 
ceptible children  escape  infection.  Epidemics  more  often  occur 
in  small  towns  and  in  rural  communities  than  in  the  larger  cities, 
and  there  seems  to  be  no  relationship  between  the  disease  and 
the  more  common  insanitary  conditions  of  dwelhng-houses.  It 
has  been  thought  that  the  presence  of  much  dust  in  the  air, 
raised  from  roadways  by  motor  traffic,  may  have  some  effect  in 
propagating  the  disease,  and  flies  may  possibly  play  some  part  in 
transmission.  In  the  United  States  the  biting  stable-fly — ■ 
Stomoxys  calcitrans — is  regarded  as  a  possible  agent  in  the  spread 
of  infection. 

There  appears  to  be  considerable  variabihty  both  in  the  in- 
fectivity  and  the  virulence  of  the  causative  agent,  as  not  only 
do  many  apparently  susceptible  persons  who    are    exposed  to 


COMMUNICABLE    DISEASES  497 

infection,  escape,  but  when  illness  does  result,  it  exhibits  such 
varying  types  of  severity.  Thus,  cases  occur  (i)  resulting  in 
extensive  and  lasting  paralysis  of  groups  of  muscles;  (2)  in  per- 
manent slight  paralysis;  (3)  in  transient  paralysis  ending  in  com- 
plete recovery;  (4)  cases  without  definite  paralysis,  but  only 
muscular  weakness  of  short  duration. 

In  poliomyelitis  the  cerebro-spinal  fluid  is  clear,  but  lympho- 
cytes are  present,  and  no  micro-organism  is  discoverable. 

As  regards  preventive  measures,  poliomyelitis  should  be  made 
a  compulsorily  notifiable  disease.  Cases  of  the  disease  should  be 
isolated  as  far  as  possible,  and  amongst  the  workingclasses  are 
best  removed  to  hospital.  Discharges  and  soiled  articles  from 
patients  should  be  disinfected.  To  prevent  the  spread  of  the 
disease  by  healthy  contacts  or  by  suspects,  the  throats  and  nasal 
passages  of  such  persons  should  be  sprayed  with  i  per  cent,  solu- 
tion of  peroxide  of  hydrogen,  or  i  in  500  permanganate  of 
potassium  solution.  Children  from  infected  homes  should  be 
excluded  from  school. 

Epidemic  Pneumonic  Fever. 

That  pneumonia  may  occur  in  epidemics,  or  even  pandemics, 
has  been  recognized  for  many  years.  The  mortality  of  several 
outbreaks  in  this  country  has  attained  the  proportion  of  5  per 
1,000  living  of  the  community.  So  far  as  has  been  ascertained, 
neither  meteorological  nor  insanitary  conditions  appear  to 
exercise  any  marked  influence  on  the  epidemic  prevalence  of 
pneumonia. 

Puerperal  Fever. 

Puerperal  fever  is  generally  caused  by  the  introduction  of 
infection  into  the  genital  tract  from  without  the  body,  and 
usually  by  the  neglect  of  aseptic  precautions  as  regards  the  hands 
and  obstetric  instruments,  during  and  immediately  after  child- 
birth. The  term  "puerperal  fever "  has  been  defined  by  the  Royal 
College  of  Physicians  of  London  as  including"  septicaemia,  pyaemia, 
septic  peritonitis,  septic  metritis,  and  other  acute  septic  inflamma- 
tions in  the  pelvis,  occurring  as  the  direct  result  of  childbirth." 

Various  micro-organisms  have  been  found  associated  with  the 
disease,  e.g..  Streptococcus  pyogenes,  Staphylococcus  aureus,  the 
Gonococc'US ,  and  Bacillus  coli  communis. 

Insanitary^conditions,  more  especially  the  fouling  of  air  by 
overcrowding"and  drainage  defects,  probably  play  some  part  in 

32 


498  HYGIENE   AND   PUBLIC   HEALTH 

determining  the  occurrence  of  the  disease ;  and  there  is  some 
evidence  that  the  infections  of  erysipelas  and  of  scarlet  fever 
have  some  relationship  to  that  of  puerperal  fever. 

To  prevent  the  spread  of  "  puerperal  fever,"  the  midwife  or 
lying-in  attendant  should  cease  attendance  on  other  lying-in 
women  until  thorough  disinfection  has  been  accomplished.  This 
should  include  a  hot  bath  for  the  person,  with  the  use  of  soap 
and  disinfectants,  thorough  cleansing  with  soap  and  disinfectants 
of  the  hair,  hands  and  finger-nails;  steam  disinfection  of  all 
personal  clothing;  and  sterilizing  in  boiling  water  of  all  mid- 
wifery instruments,  catheters,  and  douches.  The  obstetric  bag 
should  be  sprayed  inside  and  out  with  a  disinfectant  spray,  and 
a  clean  lining  and  pockets  substituted  for  the  old  ones. 

Cancer. 

The  causes  determining  the  prevalence  of  this  disease  are 
still  wrapped  in  obscurity,  and  the  view  that  cancer  is  due  to  a 
parasite,  which  possesses  some  degree  of  infectiveness,  is  losing 
ground.  Certain  investigations  seemed  to  indicate  that  cancer, 
like  enteric  fever,  has  an  endemic  prevalence,  and  that  it  affects 
in  a  higher  degree  populations  living  in  low-ljdng  river  valleys 
with  clay  soils  than  those  on  high,  dry,  and  non-retentive  soils. 
Such  endemic  areas  might  be  close  to  others  on  which  the  disease 
rarely  occurred;  and  isolated  "  cancer  houses,"  or  groups  of  such 
houses,  in  which  successive  families  have  suffered  from  cancer, 
though  in  no  way  related  to  each  other,  were  held  by  many  to 
exist  in  certain  districts;  but  the  evidence  both  as  to  endemic 
areas  and  cancer  houses  is  by  no  means  strong. 

All  races  of  mankind  are  liable  to  cancer,  and  likewise  all  verte- 
brate animals — with  the  possible  exception  of  reptiles — whether 
they  be  living  in  a  state  of  nature  or  in  captivity.  The  histo- 
logical lesions  characteristic  of  the  disease  throughout  the  verte- 
brates are  identical  with  those  found  in  man.  Cancer  in  the 
lower  animals  has  the  same  higher  incidence  in  old  age,  and 
therefore  the  same  relation  to  the  duration  of  life  as  in  man. 
Cancer  has  been  successfully  inoculated  from  mouse  to  mouse, 
the  new  tumour  being  of  exactly  the  same  nature  as  the  original 
one.  A  mouse  cancer  will  only  grow  in  other  mice  of  the  same 
race;  that  is  to  say,  a  wild  mouse  cannot  be  inoculated  with 
tame  mouse  cancer,  and  vice  versa.  Propagation  succeeds  as 
well,  and  perhaps  better,  in  young  mice  as  in  old  ones.     The 


COMMUNICABLE  DISEASES 


499 


cancer  cells  transmitted  experimentally  from  one  mouse  to 
another  continue  to  grow  and  divide  in  the  inoculated  mouse. 
The  tissues  of  the  new  host  do  not  acquire  any  cancerous  pro- 
perties; they  merely  react  to  the  presence  of  the  cancer  cells,  and 
supply  them  with  nourishment.  The  process  is  fundamentally 
different  from  all  known  processes  of  infection.     (Bashford.) 

The  death-rate  from  cancer  varies  considerably  in  different 
parts  of  England  and  Wales,  ranging  in  the  year  1905  from  483 
and  763  among  males  and  females  respectively,  in  Durham; 
526  and  717  respectively,  in  Glamorganshire,  to  1,400  and  1,504 
among  males  and  females  respectively,  in  Huntingdonshire,  and 
1,190  and  1,611  respectively  in  Cardiganshire. 

During  the  past  fifty  years  there  has  been  an  increased  mor- 
taUty  registered  from  the  disease  in  England  and  Wales,  as  the 
following  table  serves  to  show: — 


Deaths 

PER   1,000,000  Living 

.\T 

ALL 

Ages. 

1851-60. 

1    1861-70. 

1871-80. 

i83i 

-90. 

1891-1900. 

igoi-icios. 

Mal&s    .     . 
Femaleir     . 

'95 
434 

242 

510 

312 
617 

430 
739 

598 
903 

723 
997 

This  increase  is  probably  not  altogether  real,  but  is  to  some 
extent  due  to  better  diagnosis  and  certification  of  causes  of 
death.  "  The  cancerous  affections  of  males  are  in  much  larger 
proportion  internal  or  inaccessible  than  are  those  of  females, 
and  consequently  are  more  difficult  of  recognition;  so  that  any 
improvement  in  medical  diagnosis  would  add  more  to  the  male 
than  to  the  female  figures  "  (Ogle).  It  is  a  significant  fact, 
therefore,  that  among  males  aged  thirty-five  to  forty- five  the 
rate  of  increase  has  been  89  per  cent.,  while  among  females  of 
the  same  age  it  has  not  exceeded  37  per  cent.  Moreover,  in 
Frankfort-on-Main,  the  deaths  are  classified  into  those  from 
cancer  of  inaccessible  and  of  accessible  regions,  and  the  increase 
of  cancer  is  confined  to  the  former.  The  greater  number  of 
survivals  of  late  years  to  the  higher  ages  will  also  account  for 
a  slight  increase  in  the  incidence  of  a  disease  of  a  degenerative 
type  such  as  cancer.  But  despite  these  facts  some  of  the  increase 
appears  to  be  real,  and  in  this  increase  there  is  a  marked  pre- 
dominance of  cancer  of  the  digestive  organs. 

As  compared  with  twenty  years  ago,  cancer  of  the  stomach. 


500  HYGIENE    AND    PUBLIC    HEALTH 

intestines,  rectum,  and  liver  has  shown  a  notable  increase  in  both 
sexes,  whilst  cancer  of  the  tongue,  oesophagus,  and  bladder  has 
shown  a  marked  increase  in  males  only.  For  females  there  has 
been  a  considerable  increase  in  cancer  of  the  breast,  but  there  has 
actually  been  a  decrease  in  cancer  of  the  uterus  and  ovary.  The 
fact  that  the  increased  mortahty  of  both  sexes  from  cancer  is 
especially  marked  at  ages  subsequent  to  forty-live  years  of  age 
in  females,  and  thirty-five  years  in  males,  and  that  the  increased 
mortality  rises  in  both  sexes  with  an  advance  in  age,  is  suggestive 
of  the  larger  proportion  of  old  people  in  the  community  at  the 
present  time,  owing  to  the  lowered  general  death-rate,  and  the 
consequent  saving  of  life  in  the  earlier  age-periods.  But  some 
of  the  increase  of  mortality  in  the  later  periods  of  life  may  be 
due  to  improved  operative  procedures  in  surgery,  lives  being 
prolonged  by  operation,  but  eventually  dying  of  a  recurrence  of 
the  growth,  which  it  was  not  in  the  power  of  the  surgeon  wholly 
to  eliminate. 

Percentage  Increase  in  Cancer  Mortality  at  Several  Age-Periods 
AMONGST  Males  and  Females  between  i  886-1 890  and  1906- 1909. 


Cancct  Mortalities  in  1886-1890  taken  as  100. 

35-45- 

45-55-                 55-65- 

,                 '       75  and 
5  '-''            upwards. 

Males      .... 
Females  .     . 

141 
100 

154       i       167 
115              129 

181                   196 
150                ^7i 

Statistics  fail  to  show  any  true  hereditary  tendency;  and  as 
to  the  cause  of  the  disease  our  present  knowledge  admits  of  little 
more  than  the  statement  that  local  irritation  and  the  abuse  of 
alcohol  appear  to  predispose  to  it. 

Rheumatic  Fever. 

It  is  now  recognized  that  this  disease  is  a  specific  disease,  and 
quite  distinct  as  to  its  origin  from  ordinary  rheumatism.  The 
facts  supporting  this  view  arc: — (i)  Excessive,  or  even  epidemic,, 
prevalence  tends  to  manifest  itself  at  irregular  intervals  of  from 
three  to  six  years.  Longstaff  has  shown  the  very  striking  analogy 
that  exists  between  the  mortality  curves  in  this  country  of 
rheumatic  fever,  erysipelas,  and  puerperal  fever  both  when 
plotted  out  as  annual  death-rates  for  a  period  of  years,  and  also, 
when  drawn  to  represent  the  average  weekly  deaths  of  a  series  qf. 


COMMUNICABLE   DISEASES  501 

twenty  years.  The  annual  curves  and  the  seasonal  curves  of  all 
three  diseases  rise  and  fall  together  in  a  very  remarkable  manner, 
suggesting  if  not  an  actual  community  of  origin,  at  any  rate 
a  co-relation  of  distinctive  character.  (2)  Dr.  Newsholme's 
researches  have  shown  that  there  is  a  very  definite  relationship 
between  deficient  rainfall,  low  ground  water,  and  high  soil 
temperature  on  the  one  hand,  and  the  prevalence  of  rheumatic 
fever  on  the  other.  In  Norway  the  disease  is  compulsorily 
notifiable  by  medical  attendants,  and  exceptional  opportunities 
are  thus  afforded  in  that  country  of  studying  the  epidemiology 
of  the  disease.  Elsewhere,  the  evidence  collected  is  generally 
derived  from  hospital  returns.  (3)  The  type  of  the  pyrexia,  and 
the  articular  and  cardiac  disturbances,  are  best  explained  on  the 
microbic  doctrine.  (4)  The  marked  effect  of  the  administration 
of  salicylates  has  long  been  claimed  as  proof  in  support  of  the 
specific  nature  of  the  disease.  Several  bacteriologists  in  this 
country  and  abroad  have  described  a  diplococcus  in  acute  rheu- 
matism, which  they  have  isolated  from  the  endocardium,  peri- 
cardium, fibrous  nodules,  tonsils,  and  urine  in  cases  of  the  disease. 
When  inoculated  into  animals  (rabbits),  the  latter  die  with 
arthritic  and  cardiac  lesions  from  which  the  diplococcus  has 
again  been  isolated. 

Syphilis. 

There  can  be  little  doubt  that  the  causative  organism  of  this 
disease  is  the  Spirochceta  pallida,  an  extremely  minute  and 
delicate,  spirally  twisted,  thread-like  organism,  which  is  actively 
motile,  the  character  of  the  movements  being  a  rapid  rotation 
on  its  long  axis  as  well  as  a  progressive  movement  (Leishman). 
The  organism  is  present  in  the  substance  of  and  in  the  discharges 
from  the  primary  sore  or  chancre,  and  can  best  be  seen  under 
a  high  power  of  the  microscope  with  dark  ground  illumination, 
when  the  spirochsete  will  be  observed  as  an  actively  moving, 
illuminated  object  against  the  dark  background.  By  this  means 
it  is  possible  to  make  a  diagnosis  of  sj^philis  on  the  first  appear- 
ance of  a  venereal  sore,  although  the  failure  to  find  Spirochceta 
pallida  does  not  necessarily  imply  that  the  venereal  sore  is  not 
specific.  The  spirochsetes  may  also  be  found  in  the  indurated 
glands,  in  the  various  secondary  eruptions  of  syphilis,  and  also 
in  the  blood  of  syphilitic  patients  in  certain  stages  of  the  disease. 
They  are,  however,  only  very  rarely  found  in  the  tertiary  lesions 
of   syphilis.     In   congenital   syphilis,    on    the   other   hand,    the 


502  HYGIENE    AND    PUBLIC    HEALTH 

spirochaetes  may  often  be  found  in  large  numbers  and  widely 
distributed  in  the  tissues. 

There  is  good  reason  to  believe  that  there  is  a  considerable 
amount  of  syphilis  in  the  community,  and  that  certain  common 
and  fatal  diseases,  which  were  not  formerly  regarded  as  having 
any  connection  with  syphilis,  are  in  reality  the  late  after-effects 
of  syphilitic  infection.  Amongst  these  may  be  mentioned  general 
paralysis,  tabes  dorsalis,  aortic  sclerosis,  sometimes  resulting  in 
aortic  aneurysm,  and  possibly  congenital  idiocy  or  imbecility 
as  a  result  of  congenital  syphilis.  The  first  three  of  these  diseases 
are  now  often  designated  "  para-syphilitic  "  affections. 

The  serum  diagnosis  of  syphilis,  which  has  been  rendered  pos- 
sible by  the  researches  especially  of  Wassermann,  Neisser,  and 
Bruck,  is  now  capable  of  referring  these  so-called  "  para-syphi- 
litic "  affections  to  their  true  origin,  and  also  enables  a  diagnosis 
to  be  made  in  cases  of  tertiary  syphiUs  of  uncertain  nature. 
(For  an  explanation  of  the  Wassermann  reaction,  see  p.  422.) 

In  this  country  an  attempt  was  made  by  the  Contagious 
Diseases  Act  of  1864  to  limit  the  spread  of  venereal  diseases  in 
certain  military  and  naval  garrison  towns.  Any  woman  charged 
with  being  a  prostitute  and  diseased,  and  plying  her  trade  within 
certain  limits,  could  be  summoned  before  a  magistrate,  who  had 
power  to  order  her  to  be  taken  to  a  certified  hospital  for  medical 
examination.  If  found  to  be  suffering  from  a  contagious  venereal 
disease,  the  magistrate  could  order  her  detention  for  treatment 
for  a  period  not  exceeding  three  months.  A  later  Act  of  1866 
enabled  a  justice  to  order  any  woman  charged  with  being  a 
prostitute  to  submit  herself  to  a  periodical  medical  examination 
for  any  period  not  exceeding  one  year.  These  Acts  continued 
in  force  until  May,  1883,  when  an  order  was  issued  abolishing 
the  compulsory  examination  of  women;  and  they  were  finally 
repealed  in  1886. 

It  is  very  doubtful  if  these  Acts  had  any  real  effect  in  con- 
trolling the  spread  of  venereal  disease  in  English  garrison  towns. 
Only  a  certain  proportion  of  the  diseased  prostitutes  were  ever 
brought  under  control  in  the  manner  indicated  by  the  Acts; 
whilst  those  who  escaped  police  supervision,  and  the  men  who 
consorted  with  them,  were  free  to  spread  infection  with  im- 
punity. Notwithstanding  the  absence  of  any  CD.  Acts,  the 
prevalence  of  venereal  diseases  in  the  British  army  in  the 
United  Kingdom  has  been  steadily  diminishing  of  recent  \^ears. 


COMMUNICABLE   DISEASES  503 

This  fortunate  result  is  attributable  to  greater  temperance 
amongst  the  soldiers,  a  higher  standard  of  education  and  intelli- 
gence, more  opportunities  for  healthful  recreation  both  of  mind 
and  body,  and  the  greater  interest  displayed  by  regimental 
officers  of  all  grades  in  the  health  and  well-being  of  the  men,  and 
in  keeping  them  fit  for  the  duties  of  their  calling. 

Although  in  the  British  army,  both  at  home  and  abroad,  much 
has  been  done  by  education,  precept,  and  rational  amusements 
for  the  men's  leisure  time  to  reduce  the  incidence  of  venereal 
disease  in  the  troops,  a  very  great  deal  has  also  been  effected  by 
improved  medical  treatment,  and  especially  by  the  "  continuous  " 
treatment  with  intramuscular  injections  of  mercury  until  a  cure 
has  been  effected,  to  reduce  the  sickness  and  invaliding  from 
syphilis  that  formerly  contributed  so  largely  to  the  wasting  of 
the  ranks.  This  method  of  treatment  may  in  its  turn  be  re- 
placed by  the  new  anti-syphilitic  remedy  devised  by  Ehrlich, 
who,  in  the  substance  known  as  dioxi-diamido-arseno-benzol 
("  606  "),  appears  to  have  evolved  a  substance  which  is,  on 
injection,  absolutely  destructive  to  the  specific  organism;  whilst 
in  the  small  doses  of  about  0-5  to  07  gramme  required  for  this 
purpose  it  is  believed  to  be  without  actively  injurious  effect 
on  healthy  living  tissues.  The  treatment,  however,  is  still  in 
an  early  experimental  stage,  and  time  must  elapse  before  the 
permanency  of  cures  can  be  attested. 

Tropical  Diseases. 

Asiatic  Cholera. 

Cholera  is  endemic  in  the  delta  of  the  Ganges,  and  probably 
also  in  other  parts  of  India  and  the  Orient.  Epidemic  extensions 
take  place  from  time  to  time,  the  disease  being  imported  from 
these  "  homes  of  cholera  "  into  far  distant  countries,  by  sea  or 
overland,  by  means  of  persons  suffering  from  it,  and  possibly  by 
means  of  infected  articles. 

The  three  main  routes  which  cholera  has  taken  from  the  endemic 
area  in  India  to  Western  Europe  are  as  follows  :  (i)  Through 
the  north-western  provinces  of  India  to  Afghanistan,  and  thence 
by  caravan  routes  to  Khiva  and  Russia;  (2)  from  Southern 
India  up  the  Gulf  of  Persia,  and  thence  to  Syria  and  Egypt,  and 
across  Persia  to  the  Caspian  Sea;  (3)  mainly  by  pilgrim  traffic 
to  the  Red  Sea  ports  and  Egypt,  and  thus  to  the  Mediterranean. 


504  HYGIENE    AND    PUBLIC    HEALTH 

The  usual  mode  of  propagation  of  cholera  is  through  drinking 
water.  The  specific  poison  is  contained  in  the  copious  bowel 
discharges  of  the  sick,  and  may  find  its  way  through  the  soil 
on  which  the  dejecta  are  thrown,  into  streams,  wells,  or  tanks. 
It  is  also  possible  that  the  contagion  is  at  times  transmitted 
through  the  air  by  the  dried  choleraic  discharges  being  borne 
into  the  air  by  currents  of  wind;  although  the  fact  that  the 
cholera  germs  are  rapidly  killed  by  drying  is  opposed  to  this 
view.  If  flies  feed  on  infected  material,  the  organisms  may  be 
found  in  them  twenty-four  hours  afterwards.  Haffkine  also  has 
shown  that  in  an  infected  district  flies  can  contaminate  milk 
with  cholera  spirilla,  if  the  milk  be  kept  in  open  vessels;  so  that 
it  seems  probable  that  cases  of  apparent  transmission  of  the 
disease  through  the  air  may  in  reality  be  due  to  the  agency  of  flies. 

Temperature  and  moisture  are  controlling  factors  of  great 
importance.  When  the  disease  is  imported  into  a  temperate 
climate,  the  intensity  of  the  epidemic  is  invariably  felt  in  the 
late  summer  and  autumn,  and  dies  away  with  the  approach  of 
cold  weather,  possibly  to  again  acquire  epidemic  intensity  in  the 
following  summer.  It  is  evident,  therefore,  that  the  specific 
virus  can  only  attain  its  full  virulence  where  the  temperature  of 
the  air,  and  therefore  of  the  soil,  is  sufficient.  The  combination 
of  moisture  and  heat  of  soil,  characteristic  of  the  Ganges  delta, 
appears  to  offer  the  most  suitable  environment  for  the  cholera 
virus. 

In  India,  Cunningham  has  shown  that  the  comma  bacilli, 
which  are  found  in  the  evacuations  of  cholera  patients,  and 
which  are  regarded  as  the  specific  cause  of  the  disease,  when 
introduced  into  polluted  water  or  soil,  tend  rapidly  to  disappear, 
as  they  are  attacked  and  destroyed  by  the  saprophytic  bacteria 
always  present  in  such  circumstances;  but  in  some  cases  they 
have  been  found  alive  even  after  two  or  three  months  in  cholera 
dejecta  kept  at  room  temperature. 

The  incubation  period  of  cholera  is  usually  very  short — one 
or  two  days;  but  it  may  occasionally  be  prolonged  for  ten  days 
or  more.  The  evacuations  are  most  infective  during  the  height 
of  the  disease.  In  epidemic  periods  the  proportion  of  deaths  to 
attacks  is  greatest  during  the  period  of  maximum  intensity  of 
the  epidemic.  When  the  epidemic  is  first  commencing,  and 
after  it  has  begun  to  subside,  the  recoveries  may  considerably 
exceed  the  numbers  of  deaths. 


COMMUNICABLE    DISEASES  505 

The  preventive  measures  which  have  hitherto  acted  most 
successfully  in  keeping  the  disease  out  of  these  islands  have 
reference  to  our  "  first  line  of  defence,"  i.e.,  the  coast.  By  far 
the  most  important  are  contained  in  the  provisions  of  the  Cholera 
Order  of  the  Local  Government  Board,  but  other  valuable 
measures  have  been:  (i)  The  Order  prohibiting  the  importation 
of  rags  from  all  infected  ports;  (2)  the  Order  prohibiting  the 
landing  of  "  filthy  and  unwholesome  aliens,"  unless  they  first 
satisfy  the  medical  officer  of  health  of  their  freedom  from 
cholera,  and  give  their  names  and  destinations ;  (3)  the  provision 
of  the  means  of  isolating  the  infectious  sick  at  our  ports;  (4)  the 
placing  of  these  ports  in  a  good  sanitary  condition  by  dealing 
with  insanitary  dwellings  and  areas,  so  as  to  remove,  as  far  as 
possible,  all  dangerous  breeding  grounds  for  the  germs;  and 
(5)  the  adoption  of  every  possible  precaution  to  safeguard  the 
purity  of  public  water  supplies. 

The  issue  of  printed  notices  by  the  local  authority,  in  which 
instruction  is  given  as  to  the  means  to  be  adopted  by  the  indi- 
vidual to  guard  against  infection,  is  a  useful  measure.  In  such 
handbills  it  should  be  stated  that  raw  vegetables  and  fruit 
should  be  avoided;  that  extreme  cleanliness  in  the  household 
should  be  adopted,  since  cholera  is  essentially  a  filth  disease; 
that  all  milk  and  water  should  be  boiled  shortly  before  use ;  and 
that  on  the  occurrence  of  diarrhoea  in  any  individual,  medical 
advice  should  be  at  once  sought. 

When  the  danger  of  an  outbreak  becomes  imminent  in  any 
district,  a  staf^  of  nurses  should  be  enlisted,  arrangements  made 
for  the  use  of  any  available  buildings  as  temporary  hospitals,  a 
large  stock  of  disinfectants  provided  for  gratuitous  distribution, 
and  measures  taken  for  the  supply  to  medical  practitioners  of 
anticholera  inoculations. 

Outbreaks  of  cholera  have  often  been  preceded  by  sporadic 
cases  of  severe  diarrhoea,  which  are  probably  unrecognized  cases 
of  the  disease. 

The  provisions  of  the  Cholera  Order  have  supplanted  those 
of  Continental  quarantine  in  these  islands,  and  are  doubtless 
far  more  successful  in  practice.  The  facts  which  tell  against 
the  efficiency  of  quarantine  as  practised  elsewhere,  are  certainly 
sufficiently  strong  to  warrant  the  adoption  by  all  countries  of 
the  English  system.  The  detention  of  persons  on  board  an 
infected  ship  for  many   days  is  not   a  measure  calculated  to 


506  HYGIENE    AND    PUBLIC   HEALTH 

protect  the  healthy  from  infection  and  to  Umit  the  spread  of  the 
disease,  whilst  the  delays  thus  caused  are  ruinous  to  trade.  Such 
measures  have  been  shown  to  be  unnecessary  in  this  country, 
and,  owing  to  frequent  evasions,  they  often  fail  in  their  object  of 
keeping  the  disease  out  of  foreign  ports.  In  Malta  the  provisions 
of  Italian  quarantine  continue  to  be  practised,  but  the  British 
system  is  in  apphcation  at  Gibraltar;  the  result  is  that  Gibraltar 
generally  escapes  from  imported  infectious  disease,  whereas  Malta 
almost  invariably  suffers.  A  very  vigorous  system  of  quarantine, 
moreover,  utterly  failed  to  prevent  cholera  crossing  the  great 
natural  barrier  afforded  by  that  huge  inland  sea,  the  Caspian, 
when  the  disease  appeared  on  its  eastern  shores  on  the  occasion 
of  the  last  great  visitation  of  cholera  to  Europe. 

Land  quarantine — by  which  is  implied  the  drawing  of  a  cordon 
of  soldiers  or  pohce  round  an  infected  area — generally  also  fails 
in  its  purpose. 

Dysentery. 
This  is  not  a  disease  of  common  occurrence  in  this  country, 
except  perhaps  in  lunatic  asylums,  where  it  is  known  as  colitis. 
It  is  distinguished  chnically  from  acute  diarrhoea  (summer 
diarrhoea,  English  cholera)  by  the  fact  that  the  stools  contain 
slime  and  blood,  and  there  is  much  tenesmus.  The  disease  also 
has  a  great  tendency  to  become  chronic,  which  is  unusual  in 
summer  diarrhoea. 

Dysentery  is  a  very  common  and  fatal  disease  in  tropical 
countries.  In  temperate  climates  it  is  rarely  seen  except  in 
times  of  war  or  famine.  It  is  eminently  associated  with  condi- 
tions of  defective  hygiene,  e.g.,  fouling  of  the  water  supply  or  of 
the  soil  in  the  neighbourhood  of  habitations  by  excreta,  over- 
crowding in  houses  or  in  camps,  and  insufficient,  coarse,  or  bad 
food.  In  tropical  and  sub-tropical  countries,  where  these  in- 
sanitary conditions,  or  some  of  them,  continuously  prevail, 
dysentery  tends  to  become  endemic,  and  to  assume  epidemic 
proportions,  if  circumstances  are  favourable  to  its  spread. 

There  are  many  varieties  of  dysenteric  disease,  and  but  very 
little  is  known  as  to  their  causes,  or  as  to  whether  they  are  types 
of  the  same  disease  differing  merely  as  to  their  severity,  or 
whether  the  different  varieties  may  not  be  distinct  entities  each 
having  a  different  mode  of  origin  and  method  of  propagation. 
One  type  of  dysentery  is  known  as  "  amoebic  dysentery,"  from 
the  fact  that  in  this  type  a  protozoon,  the  Amoeba  coli,  is  in- 


COMMUNICABLE   DISEASES  507 

variably  present  in  the  stools;  but  it  is  not  known  with  any 
certainty  that  the  amoeba  is  actually  the  cause  of  the  dysentery. 
There  are  many  cases  of  dysentery,  and  even  some  having  a  great 
clinical  resemblance  to  amoebic  dysentery,  in  which  the  amoebai 
cannot  be  found;  moreover  an  amoeba,  indistinguishable  from 
the  dysentery  amoeba,  is  sometimes  found  in  the  healthy  stools 
of  people  in  good  health.     According  to  Schaudinn,  however, 
there  are  two  varieties  of  amoeba  to  be  found  in  the  intestine — 
one  a  pathogenic  and  the  other  a  saprophytic  organism,  which 
differ  somewhat  from  each  other  in  morphology  and  in  methods 
of  reproduction.     The  Amceba  coli  is  very  frequently  found  in 
the  contents  of  the  liver  abscesses,  which  are  so  often  associated 
with    chronic    dysentery,    and    this    indicates    the    presence    of 
amoebae    in    the    intestinal    tissues    around    dysenteric    ulcers. 
Amceba  coli  is  seldom  found  in  the  stools  during  epidemic  preva- 
lence of  dysentery.     In  these  epidemic  cases  Shiga  has  isolated 
a  bacillus  {Bacillus  dysenteria;)  which  somewhat  resembles  the 
Bacillus  typhosus,  and  whilst  it  does  not  agglutinate  in  serum 
from  typhoid  cases,  agglutinates  with  the  blood  serum  of  cases 
of  epidemic  dysentery  in  dilutions  of  one  in  ten.     This  bacillus 
has  some  claim  to  be  regarded  as  specific  in  epidemic  types  of 
dysentery. 

In  some  cases  of  colitis,  or  asylum  dysentery,  in  this  country 
Durham  has  isolated  a  micrococcus,  so  minute  that  it  readily 
passes  through  a  Berkefeld  filter,  from  the  blood,  liver,  spleen, 
kidney,  and  bile  of  affected  patients. 

Dysentery  is  undoubtedly  to  a  large  extent  a  water-borne 
disease,  like  enteric  fever,  but  like  the  latter  disease  its  propaga- 
tion is  at  times  effected  by  means  of  dust  and  flies.  Much  hght 
was  thiown  on  these  methods  of  dissemination  of  the  disease 
during  the  South  African  Boer  war.  As  in  cholera,  and  other 
tropical  diseases,  chill,  bad  or  irritating  food,  mental  depression, 
etc.,  play  a  very  important  part  as  predisposing  causes,  and  are 
by  many  still  regarded  as  the  exciting  causes  of  dysentery. 

Plague. 
An  epidemic  disease  having  the  character  of  bubonic  plague 
is  referred  to  by  many  old  writers,  as  far  back  as  2,000  years 
ago,  as  prevalent  in  Egypt,  Libya,  and  other  parts  of  North 
Africa.  The  most  appalling  European  visitation  was  that  in 
the  fourteenth  century,   known  as  the  "  Black  Death,"  which 


508  HYGIENE  AND  PUBLIC  HEALTH 

was  supposed  to  have  had  its  origin  in  China  in  1334;  this  out- 
break lasted  many  years.  The  Great  Plague  of  London  made 
its  appearance  in  1664,  lasted  about  one  year,  and  destroyed  at 
least  63,000  persons. 

China  and  the  western  parts  of  India  appear  to  have  always 
suffered  most;  and  it  is  generally  recorded  that  plague  has 
attacked  districts  for  a  number  of  successive  years,  with  short 
intervening  periods  of  apparent  freedom. 

China  does  not  seem  to  have  suffered  much  in  recent  years. 
For  example,  it  has  not  been  present  in  Pekin,  Shanghai,  and 
other  large  towns,  but  only  in  Hong  Kong.  Occasionally  from 
here  it  has  found  its  way  to  Canton  and  Macao  bj'  direct  inter- 
course, but  even  then  it  appears  not  to  be  able  to  get  a  footing. 

Although  rare  in  equatorial  regions,  it  occurs  in  hot  and  cold 
weather,  wet  and  dry  seasons,  on  dry  and  damp  sites,  and  at 
all  altitudes.  In  India  plague  generally  decreases  during  the 
hottest  weather,  and  recrudesces  with  the  onset  of  the  colder 
seasons. 

The  disease  is  of  microbic  origin,  and  is  due  to  the  bacillus 
isolated  at  Hong  Kong  in  1894  by  Kitasato  and  Yersin.  This 
bacillus  is  found  post-mortem  in  the  blood,  the  spleen,  and 
other  internal  organs,  also  in  the  unopened  buboes,  the  sputum, 
faeces,  and  urine.  The  infection  can  be  contracted  by  inocula- 
tion, inhalation,  or  by  swallowing;  and  human  sufferers  are  not 
the  sole  carriers  of  contagion.  Rats,  mice,  bandicoots,  guinea- 
pigs,  monkeys,  pigs,  and  probably  sheep,  goats,  dogs,  and  other 
animals  may  also  suffer  from  the  disease,  which  in  China  and  the 
Himalayas  has  long  been  called  the  "  rats'  disease."  Fleas  and 
flies  have  been  shown  to  die  in  large  numbers  in  plague  labora- 
tories, and  to  contain  the  Bacillus  pesiis.  Like  mosquitoes  they 
may  act  as  carriers.  There  is  evidence  to  show  that  black  or 
Indian  rats  may  be  affected  before  human  beings;  and  it  is 
certain  that  the  continuance  and  spread  of  the  disease  is  favoured 
by  the  presence  of  these  highly  susceptible  animals,  many  out- 
breaks having  been  attributed  to  infected  rats,  conveyed  from 
an  infected  to  a  non-infected  port  in  grain-carrying  ships.  It 
is  practically  certain  that  the  infection  is  conveyed  from  rat  to 
rat,  and  from  rats  to  human  beings  by  means  of  fleas,  and  that 
on  the  death  of  a  plague-stricken  rat,  the  fleas — already  engorged 
with  bacilli — leave  the  body  and  find  their  way  into  houses 
where  they  attack  man,  inoculating  him  through  the  "  bites." 


COMMUNICABLE    DISEASES  50g 

It  IS  also  highly  probable  that  inoculation  of  man  occurs 
through  the  excreta  of  fleas,  which  swarm  with  B.  pesiis  in 
infected  insects.  The  flea  deposits  excreta  on  the  human  skin, 
and  inoculation  takes  place  when  the  skin  is  scratched  with  the 
finger-nails  to  allay  irritation.  The  bacilli  so  inoculated  are 
carried  by  the  lymphatic  vessels  of  the  skin  to  the  lymphatic 
glands  (usually  of  the  groins  or  armpits),  as  the  legs  and  arms 
are  most  likely  to  be  flea-bitten. 

The  flea  {Zenopsylla  cheopis)  of  the  black  or  Indian  rat  {Mus 
rattiis)  closely  resembles  the  common  flea  of  man  {Pulex  irritans), 
but  is  smaller  and  of  lighter  brown  colour.  The  black  or  Indian 
rat  is  essentially  a  house-rat,  and  lives  in  close  association  with 
human  beings.  As  the  natives  of  India  and  the  East  live  very 
commonly  in  rat-infested  houses,  plague  is  especially  a  disease 
of  the  natives.  The  houses  of  Europeans  in  tropical  countries 
are  either  so  constructed  as  to  be  rat-proof,  or  rats  are  extermin- 
ated and  not  allowed  to  multiply  in  European  residences.  The 
flea  (Ceratophyllus  fasciatus)  of  the  brown  or  European  rat  {Mus 
decumanus)  is  not  known  to  be  concerned  in  the  transmission 
of  plague  from  rat  to  man  in  anything  like  the  same  degree  as 
the  flea  of  the  black  rat ;  but  it  may  transmit  the  disease  from  rat 
to  rat  in  England  and  other  countries,  and  occasionally  it  may 
convey  the  disease  from  rat  to  man.  The  brown  rat,  which  is 
larger  and  fiercer  than  the  black  rat,  was  introduced  into  England 
in  the  eighteenth  century,  and  gradually  drove  out  and  exter- 
minated the  black  rat,  which  was  the  original  inhabitant  of  the 
British  Isles.  The  brown  rat  is  not  a  house-dweller  like  the 
black  rat,  but  lives  in  out-buildings,  ditches,  drains,  or  the  open 
country;  consequently  it  does  not  come  into  close  association 
with  man  like  the  black  rat.  This  may  be  the  chief  reason 
why  the  occurrence  of  plague  in  the  rats  of  a  locality  in  this 
country  is  not  followed  by  an  epidemic  amongst  human  beings, 
as  so  frequently  occurs  in  India. 

Klein  states  that  the  B.  pesiis  as  found  in  the  rat  is  of  a 
different  type  to  that  isolated  from  man.  The  human  type  is 
much  more  virulent  than  the  rat  type,  and  they  present  also 
permanent  and  definite  differences  in  morphological,  cultural, 
and  physiological  respects.  The  rat  type  quickly  loses  its  virulence 
when  sub-cultured  artificially,  whereas  the  human  type  retains 
its  virulence  for  long  periods  during  sub-culture,  and,  unlike  the 
rat  type,  recovers  full  virulence  by  a  renewed  passage  through 


510  HYGIENE   AND   PUBLIC   HEALTH 

the  animal  body.  The  original  virulence  of  the  rat  type,  when 
once  lost,  cannot  be  regained  by  animal  passage. 

Direct  contagion  from  the  sick  to  the  healthy  appears  to  be 
a  minor  cause  of  spread,  Europeans  having  suffered  but  very 
little  while  in  attendance  on  Indian  patients.  Like  typhus  fever, 
plague  appears  to  be  associated  with  conditions  of  poverty,  filth, 
and  overcrowding,  and  with  soil  polluted  by  organic  matter, 
but  the  chief  cause  of  bubonic  plague  is  undoubtedly  the  in- 
habiting by  human  beings  of  rat-infested  dwelhngs.  It  has  not 
yet  been  demonstrated  that  drinking  water  has  acted  as  a 
disseminator  of  the  virus,  although  experiments  show  that  the 
plague  organism  can  live  for  a  long  time  in  water.  Fomites 
retain  and  spread  the  infection. 

There  are  three  distinct  types  of  the  disease: — the  bubonic, 
the  pneumonic,  and  the  septicaemic;  but  the  first  named  is  so 
much  more  common  than  the  others  that  the  disease  is  very 
generally  known  as  "  bubonic  plague." 

In  pneumonic  plague  the  bacilli  of  plague  are  found  present  in 
large  numbers  in  the  sputum  and  in  the  droplets  of  foam  or 
froth  ejected  from  the  lungs  during  coughing.  This  form  of  the 
disease  is  therefore  highly  contagious,  and  no  one  should  approach 
a  case  of  pneumonic  plague  without  the  protection  afforded  by 
a  well-fitting  mask  over  the  face,  nose,  and  mouth.  The  septi- 
caemic form  of  plague  must  also  be  regarded  as  highly  infectious. 

The  incubation  period  of  bubonic  plague  varies  from  two  to 
seven  days;  and  generally  within  twenty- four  hours,  or  less, 
from  the  onset  of  symptoms  the  buboes  appear  in  the  groin,  the 
armpit,  the  region  of  the  neck,  or  more  rarely  elsewhere.  Death 
frequently  takes  place  within  forty-eight  hours  of  the  onset  of 
symptoms,  a  fatal  result  being  rare  after  the  eighth  day.  The 
disease  varies  so  much  in  its  clinical  aspects  and  severity  as  to 
justify  a  rough  classification  of  cases  into  severe  and  mild  (pestis 
major  and  pestis  minor) ;  but  the  tendency  nowadays  is  to 
restrict  the  term  pestis  minor  to  cases  of  enlargement  of  glands 
(not  venereal  in  origin),  which  are  often  seen  just  before  and 
during  a  true  outbreak  of  plague,  and  in  which  the  Bacillus  pestis 
cannot  be  demonstrated. 

The  preventive  measures  against  the  disease  include:  The 
compulsory  notification  of  the  disease,  the  discovery  of  cases  by 
house  -  to  -  house  inspection  (where  necessary) ,  and  the  early 
bacteriological  .cJiagnosis  p/  the  mild  or  "  ambulant  "  types  of 


COMMUNICABLE   DISEASES  511 

the  disease  which  have  been  observed  to  precede  an  outbreak.^ 
Prompt  and  efficient  isolation  and  disinfection  should  follow 
upon  the  discovery  of  the  cases;  and  those  living  in  the  same 
house  with  a  plague  patient  (the  so-called  "  contacts  ")  should 
be  removed  from  their  homes  to  a  quarantine  house,  to  be  kept 
under  observation  for  ten  days.  Both  prophylactic  and  curative 
inoculations  with  Haffkine's  vaccine  and  Yersin's  plague  serum, 
respectively,  are  further  measures  of  undoubted  value,  which 
should  be  practised  when  possible.  The  total  destruction  of 
the  rats  in  an  infected  area  is  eminently  desirable  to  check  the 
spread  of  the  disease,  but  the  due  execution  of  this  precaution 
has  hitherto  presented  insuperable  practical  difficulties.  People 
should  be  advised  to  keep  their  houses  rat-free,  and  if  possible 
rat-proof,  by  domestic  cleanliness  and  the  frequent  collection 
and  disposal  of  house-refuse;  to  provide  no  food  for  rats;  and  to 
keep  dogs  or  cats.  The  number  of  rats  may  be  materially 
reduced  by  trapping  or  poisoning,  by  hunting  with  dogs  and 
ferrets,  or  by  asphyxiating  them  in  their  hiding  places  with  a 
mixture  of  carbonic  acid  and  carbon-monoxide  gases,  or  with 
sulphurous  acid  gas,  and  their  dead  bodies  should  be  immediately 
burned.  Efforts  have  been  made  with  some  success  to  com- 
municate an  epizootic  disease  to  rats  and  mice  by  means  of  the 

1  The  following  directions  for  obtaining  and  forwarding  for  bacterioscopic 
examination  material  from  a  suspected  case  of  plague,  have  been  issued 
by  the  Medical  Officer  of  the  Local  Government  Board: 

(a)  From  the  living  person: — 

1.  Clean  with  soap  and  water  and  then  with  alcohol  the  last  phalanx 
of  either  the  second  or  third  finger.  When  dry,  or  after  mopping  with  a 
clean  cloth,  put  a  piece  of  tape  round  the  proximal  end  of  the  last  phalanx 
so  as  to  cause  venous  congestion.  Prick  the  palmar  surface  of  this  phalanx 
with  a  sterile  needle,  and  immediately  take  up  the  exuding  blood  in  two 
sterile  capillary  tubes  such  as  are  used  for  collecting  vaccine  lymph.  These 
tubes  when  charged  should  be  sealed  at  both  ends. 

2.  When  there  is  a  discharging  bubo,  collect  fluid  therefrom  in  capillary 
tubes  as  in  the  case  of  blood.  When  this  discharge  is  not  of  a  suificiently 
fluid  character  for  collection  in  this  way,  place  some  of  it  in  a  small  glass- 
stoppered  phial,  previously  well  washed  out  with  alcohol,  care  being  taken 
that  no  alcohol  remain  in  the  phial. 

3.  If  expectoration  be  obtainable,  collect  some  in  a  phial  in  the  manner 
prescribed  in  Section  2. 

(b)  From  the  dead  body: — 

1 .  Cut  out  any  inflamed  lymph-gland,  together  with  some  of  its  surround- 
ing tissue,  and  place  the  whole  in  a  wide-mouthed,  glass-stoppered  bottle, 
previously  well  washed  out  with  alcohol,  care  being  taken  that  no  alcohol 
remains  in  the  bottle.  The  bottle  should  have  the  stopper  well  secured 
and  sealed. 

2.  Obtain  also  a  piece  of  the  spleen,  dealing  with  it  in  the  same  manner. 


512  HYGIENE    AND    PUBLIC   HEALTH 

Danysz  bacillus,  which,  while  not  communicable  to  man,  would 
spread  among  the  rodents  and  cause  their  destruction.  What- 
ever methods  are  adopted  to  destroy  the  rats  in  a  particular 
area,  it  is  desirable  that  the  active  campaign  should  begin  at 
the  periphery  of  the  area  and  work  towards  the  centre. 

The  Danysz  bacillus  is  genetically  related  to  the  paratyphoid 
group  of  organisms,  which  also  includes  the  Bacillus  enteritidis 
of  Gaertner.  Some  care  should  be  exercised  in  the  destruction 
of  rats  by  means  of  food  which  has  been  soaked  in  cultures  of 
the  Danysz  bacillus,  as  there  is  reason  to  believe  that  human 
beings  have  been  rendered  ill  by  contamination  of  their  food  with 
this  bacillus.  There  is  some  reason  to  question  the  accuracy  of 
the  statement  that  the  Danysz  bacillus  is  harmless  to  man. 

Merchant  vessels  should  take  the  necessary  steps  for  the 
aestruction  of  rats  on  board  before  loading  and  upon  discharge, 
and  also  to  prevent  intercommunication  during  loading  and 
discharge  between  ship  and  shore  rats.  Further,  owners  of  river- 
side warehouses  and  granaries  should  make  systematic  efforts 
to  exterminate  rats,  and  to  prevent  rats  leaving  ships;  cables 
covered  with  fresh  tar  at  each  end  and  fitted  with  special  conical 
guarded  collars  should  be  used,  and  footbridges  should  be  raised 
during  the  night.  Fumigation  with  sulphurous  acid  gas 
effectually  destroys  rats  in  a  closed  hold,  but  this  can  only  be 
used  after  the  hold  is  cleared  out,  because  of  its  injurious  effect 
upon  many  cargoes.  The  admixture  of  COg  and  CO,  obtained 
from  burning  charcoal,  is  cheap  and  without  injurious  effects 
upon  the  most  delicate  goods;  it  is,  however,  a  more  dangerous 
gas  to  human  beings,  and  extreme  precautions  must  be  taken 
against  accidents.  Any  rats  found  on  a  "  suspected  "  vessel 
must  not  be  handled,  but  plunged  with  tongs  into  a  bucket  of 
carbolic  solution  until  they  can  be  burnt.  No  rats  must  be 
thrown  overboard  into  the  harbour. 

The  evacuation  of  infected  houses,  and  even  of  infected  dis- 
tricts, has  been  attended  with  good  results  in  India,  the  people 
being  housed  temporarily  some  distance  away,  while  the  sufferers 
are  isolated,  and  the  infected  clothes  and  premises  disinfected. 
To  guard  a  district  against  the  importation  of  the  disease,  all 
persons  coming  from  infected  localities  should  be  subjected  to  at 
least  seven  days'  surveillance;  and  provision  should  be  made 
for  the  medical  inspection  of  all  incoming  persons  at  the  railway 
centres,  and  at  other  means  of  approach  to  the  district.     Any- 


COMMUNICABLE    DISEASES  513 

one  found  to  be  suffering  from  the  disease  must  submit  to 
hospital  isolation,  and  suspects  must  be  detained  temporarily 
in  quarantine  camps.  As  the  disease  is  essentially  a  filth  disease, 
every  effort  should  be  made,  by  improved  scavenging  and  the 
removal  of  insanitary  conditions,  to  stamp  out  the  possible  foci 
of  infection.  Experiments  have  shown  that  a  soap  emulsion  of 
kerosene  oil  is  a  valuable  agent  in  the  disinfection  of  plague- 
infected  rooms;  and  the  fleas  exposed  to  the  action  of  this 
pulicide  are  almost  always  killed  in  two  minutes. 

Haffkine's  prophylactic  against  plague  consists  of  a  fluid  pre-' 
pared  by  growing  plague  bacilli  in  goat,  beef,  or  mutton  broth 
on  which  floats  a  small  quantity  of  clarified  butter.  The  bacilli 
attach  themselves  to  the  oil  globules,  and  form  stalactitic  growths 
projecting  into  the  broth.  After  about  four  weeks,  when  six 
crops  of  stalactites  have  been  formed,  the  culture  is  heated  to 
70°  C.  for  an  hour,  to  kill  the  Bacillus  pestis,  and  a  little  weak 
carbolic  acid  solution  is  added  to  prevent  the  growth  of  ex- 
traneous organisms.  A  copious  deposit  is  produced  which 
should  be  well  shaken  and  diffused  throughout  the  liquid  before 
the  vaccine  is  finally  bottled.  The  usual  dose  for  inoculating 
an  adult  is  2  to  3  c.c,  and  the  inoculation  should  be  repeated  in 
from  twelve  to  twenty  days.  A  good  deal  of  reaction  results, 
the  temperature  rising  to  102°  F.,  sometimes  to  104°  F.,  with  a 
feeling  of  general  malaise  and  pain  at  the  seat  of  inoculation. 
The  India  Plague  Commission  has  recently  reported  that  inocula- 
tion of  Haffkine's  fluid  sensibl}^  diminishes  the  incidence  of  plague 
attacks,  and  also  the  fatality  of  attack  among  the  inoculated 
population. 

Yersin's  serum  is  prepared  in  the  same  way  as  diphtheria 
antitoxin,  by  inoculation  of  horses  with  Hving  cultures  of  plague 
bacilli.  The  immunity  given  by  inoculation  of  Yersin's  serum 
is  of  much  shorter  duration  than  that  due  to  Haffkine's  prophy- 
lactic. Fifteen  days  is  about  the  limit  of  the  immiine  period 
due  to  the  serum,  whereas  Haffkine's  fliiid  may  be  protective 
for  several  months;  but  it  is  claimed  that  Yersin's  serum  is 
also  curative,  when  once  the  disease  has  declared  itself. 

Malaria. 
It  has  now  been  demonstrated  (Manson,  Ross,  Koch,  Grassi, 
CelU)  that  man  is  the  temporary  host,  and  the  mosquito  the 
definitive  host,  of  all  known  malarial  parasites.     In  addition  to 

33 


514  HYGIENE    AND    PUBLIC    HEALTH 

man,  however,  monkeys,  bats,  and  other  vertebrates  may  har- 
bour the  parasite;  and  Manson  suggests  that  in  the  absence  of 
vertebrates,  one  mosquito  may  become  directly  infected  from 
another,  and  so  keep  the  parasite  ahve.  These  parasites  pass 
their  asexual  life,  and  prepare  their  sexual  forms,  in  the  human 
blood,  while  they  complete  the  sexual  cycle  of  life  in  the  middle 
intestine  of  the  mosquito.  Those  mosquitoes  capable  of  affording 
lodgment  to  the  specific  parasites,  and  of  infecting  man  by  means 
of  their  punctures,  appertain  to  the  genus  Anopheles. 

Structurally  the  mosquito  consists  of  a  head,  to  which  are 
attached  the  eyes,  two  antennae  (long,  feathery  appendages), 
two  palpi  (feelers  of  varying  length),  and  the  proboscis,  by  which 
the  insect  pierces  the  skin  and  sucks  blood  from  its  victim.  The 
thorax  comes  next  to  the  head,  and  has  attached  to  it  three 
pairs  of  long,  jointed  legs,  and  one  pair  of  membranous  wings. 
The  segmented  abdomen  is  attached  to  the  thorax.  The  best 
known  of  the  malarial  mosquitoes  is  the  Anopheles  macuUpennis 
(spot-winged  Anopheles).  These  insects  may  be  distinguished 
from  most  other  mosquitoes  by  both  sexes  having  palpi  as  long 
as  the  proboscis,  which  is  straight ;  by  having  spotted  wings ;  by 
the  fact  that,  when  at  rest  on  a  fiat  surface,  the  long  axis  of  the 
body  is  almost  vertical  to  the  flat  surface,  whilst  in  most  other 
mosquitoes  it  is  parallel.  Anopheles,  moreover,  do  not  make 
so  loud  a  humming  sound  when  in  flight  as  other  species  do. 

Mosquitoes,  like  other  insects,  are  propagated  by  eggs,  which 
in  their  development  pass  through  two  stages,  that  of  larva  and 
that  of  pupa  or  nymph,  before  the  perfect  insect  emerges.  Almost 
all  mosquitoes  are  aquatic  in  their  larval  and  pupal  stages,  and 
any  small  collection  of  water  may  form  their  breeding-grounds. 
In  the  absence  of  ponds,  ditches,  surface  pools,  exposed  cisterns, 
water-butts,  or  rejected  tins  and  cans  capable  of  holding  water, 
mosquitoes  cannot  propagate,  and  die  out.  In  streams  or  ponds 
containing  fish  the  larvae  are  often  consumed  by  the  fish,  and 
but  few  adult  mosquitoes  may  develop.  The  eggs  are  laid  by 
the  female  mosquito  on  the  surface  of  the  water  either  singly 
{Anopheles  and  some  species  of  Stegomyia) ,  or  cemented  together 
in  hundreds  {Culex) ,  so  as  to  form  rafts,  which  float  on  the  surface, 
as  do  the  single  eggs,  each  being  provided  with  an  air  cell. 

A  few  days  after  the  eggs  are  deposited,  the  larvae  are  hatched 
out.  These  are  very  similar  in  all  species  of  mosquito,  and 
consist  of  a  head,  thorax,  and  segmented  abdomen  without  any 


COMMUNICABLE    DISEASES  515 

legs.  The  larva  of  Anopheles  lies  almost  horizontally  beneath 
the  surface  of  the  water,  as  it  breathes  air  in  through  an  aperture 
placed  dorsally  at  the  posterior  half  of  the  abdomen;  whilst  in 
Culex,  Stegomyia,  and  other  forms,  there  is  one  long  air  tube  at  the 
end  of  the  abdomen,  which  enables  the  larva  to  breathe  whilst 
its  body  is  immersed.  The  larvae  can,  therefore,  be  destroyed 
in  small  collections  of  water  by  floating  some  light  oil,  such  as 
paraffin,  on  the  surface  of  the  water,  which  prevents  the  absorp- 
tion of  air  through  the  breathing  pores.  This  is  one  of  the  anti- 
malarial measures  undertaken,  where  it  is  impossible  to  drain 
away  or  otherwise  abolish  the  surface  or  collected  waters  which 
form  the  breeding-grounds  of  mosqmtoes. 

The  mode  of  production  of  malaria  in  man  is  briefly  as  follows : 
In  an  infected  Anopheles  mosquito  the  veneno-salivary  glands 
lying  on  each  side  of  the  fore  part  of  the  thorax,  and  the  ducts 
leading  from  these  glands  to  the  base  of  the  mosquito's  pro- 
boscis, contain  the  spindle-shaped  sporozoites  (malarial).  When 
the  infected  female  mosquito  bites  a  man,  these  sporozoites 
are  injected  into  his  blood.  In  the  blood  the  sporozoites  multiply, 
find  entrance  into  the  red  blood  corpuscles,  and  grow  at  the  ex- 
pense of  the  haemoglobin,  so  as  to  be  recognizable  as  malarial 
parasites  eight  to  ten  days  after  infection.  The  parasite  is 
then  seen  as  a  pale  ill-defined  disc  of  protoplasm  occupying  a 
larger  or  smaller  area  of  the  red  corpuscles,  and  containing  a 
number  of  black  pigment  particles — melanin.  These  scattered 
pigment  groups  subsequently  concentrate  into  one  or  two  larger 
central  groups,  around  which  the  protoplasm  arranges  itself  in 
minute  segments,  which  finally  become  spores.  The  blood 
corpuscle  then  breaks  down,  and  the  spores  and  melanin  are 
liberated  into  the  Hquor  sanguinis.  The  melanin  and  some  of 
the  spores  are  then  absorbed  by  the  phagocytes,  but  others  of 
the  spores  attach  themselves  to  undamaged  red  blood  corpuscles, 
which  they  enter.  In  these  newly  infected  corpuscles  the  para- 
sites exhibit  active  amoeboid  movement,  shooting  out  and  re- 
tracting long  pseudo-spodia,  and  grow  at  the  expense  of  the 
haemoglobin.  As  the  parasite  becomes  larger  the  amoeboid 
movements  lessen,  and  just  before  sporulation  and  the  com- 
pletion of  the  asexual  cycle,  the  parasite  is  passive. 

At  a  later  stage  of  the  malarial  illness,  certain  sexual  forms  of 
the  parasite  may  be  seen  in  the  blood,  these  assuming  either  the 
form  of  crescents  (malignant  ague)   or  large  intra-corpuscular 


5l6  HYGIENE    AND    PUBLIC   HEALTH 

forms  (benign  ague).  In  the  male  type  of  crescent  the  protoplasm 
is  hyaline,  and  the  pigment  loosely  arranged;  in  the  female  the 
protoplasm  is  faintly  granular,  and  the  pigment  arranged  as  a 
well-defined  ring  about  the  centre  of  the  parasite.  If  human 
blood  containing  these  crescents  or  large  intra-corpuscular 
forms  is  ingested  by  the  female  Anopheles  mosquito  into  its 
stomach,  certain  changes  take  place.  In  the  male  crescents  or 
parasites  active  movements  set  in  in  the  pigment,  and  one  or 
more  fiagella  are  suddenly  shot  out  from  the  periphery  of  the 
parasite,  which  have  characteristic  waving  movements.  Some 
of  the  fiagella  break  away,  and  approaching  the  female  parasites 
enter  their  substance  through  a  minute  papilla  on  the  surface. 
Only  one  flagellum  enters  each  female;  no  second  flagellum  can 
effect  an  entrance.  After  impregnation  the  female  parasite 
assumes  a  vermicular  form,  and  becomes  motile.  It  then  pene- 
trates the  wall  of  the  mosquito's  stomach,  and  lodges  itself 
amongst  the  muscular  fibres,  and  may  here  be  seen  as  an  oval 
or  spherical  body  with  sharp  outline,  thirty- six  hours  after  the 
mosquito  has  fed  on  infected  human  blood.  During  the  next 
few  days  a  vast  number  of  minute,  slender,  spindle-shaped 
nucleated  bodies — the  sporozoites — are  developed  in  the  parasite, 
now  much  enlarged;  a  week  later  the  capsule  containing  the 
sporozoites  bursts,  and  the  'after  are  discharged  into  the  mid- 
gut of  the  mosquito.  From  here  they  pass  by  means  of  the 
blood  stream  into  the  veneno-salivary  glands,  and  the  sexual 
cycle  is  completed. 

Typical  ague  is  either  "  quartan  " — pyrexial  attack  every 
seventy- two  hours;  "  tertian  " — every  forty-eight  hours,  or 
"  quotidian  " — every  twenty-four  hours.  The  rigors  intro- 
ducing the  attack  coincide  in  point  of  time  with  the  liberation 
of  the  spores  from  the  red  corpuscles ;  and  it  is  believed  that  the 
fever  is  determined  by  the  setting  free  of  the  toxins  generated 
by  the  parasites  in  the  blood  corpuscles.  During  the  hot  and 
sweating  stages  of  the  attack  it  is  probable  that  the  toxins  are 
in  process  of  elimination  from  the  blood.  During  the  intervals 
between  the  attacks  there  occurs  the  infection  of  red  corpuscles 
not  previously  affected,  and  the  growth,  maturation,  and  sporula- 
tion  of  the  parasites  within  the  corpuscles.  In  the  remittent 
and  continued  (malignant)  types  of  malaria,  there  has  probably 
been  a  mixed  infection  with  parasites  belonging  to  the  various 
types  of  ague  above  mentioned,  together  with  the  malignant 


COMMUNICABLE   DISEASES  517 

crescent-forming  parasites,  so  that  sporulating  parasites  may 
be  met  with  at  ah  stages  of  the  disease,  and  the  fever  is  not 
intermittent,  but  continued,  with  remissions. 

Blackivater  or  Hcemoglohimtric  Fever  sometimes  occurs  in  those 
who  have  been  subject  to  occasional  attacks  of  malarial  fever. 
This  disease  is  very  frequently  fatal;  but,  if  recovered  from,  the 
malaria  parasites,  which  were  present  in  the  blood  prior  to  attack, 
generally  disappear  during  the  process  of  haemoglobinuria,  which 
may  thus  terminate  for  good  a  chronic  malarial  infection.  The 
hcemoglobinuria  secures  the  destruction  of  all  the  parasite-infected 
red  corpuscles,  and  their  included  parasites,  and  therefore  seems  to 
be  a  method  of  spontaneous  cure  of  a  malarial  infection.  Nothing 
is  known  as  to  the  cause  of  the  occurrence  of  blackwater  fever, 
apart  from  its  association  with  malarial  parasites  in  the  blood. 

The  soil  plays  only  an  indifferent  part  in  the  propagation  of 
malaria,  by  its  favouring  or  otherwise  the  hfe  and  development 
of  the  malariferous  mosquitoes.  The  most  favourable  soil  for 
malaria  is  that  which  permits  of  the  formation  and  continu- 
ance of  pools  of  stagnant  water  containing  algae  or  water  weeds, 
which  are  the  habitat  of  the  eggs,  larvaj,  and  nymphae  of  the 
genus  Anopheles.  Rice  fields,  whether  the  water  is  stagnant, 
running  or  intermittent,  always  afford  a  favourable  nidus  for 
the  Anopheles  larvae. 

It  is  generally  admitted  that  chilling  of  the  body  predisposes 
both  to  the  onset  of  the  primary  infection  and  to  relapses.  The 
inhabitants  of  malarious  districts  in  the  tropics  acquire  some 
degree  of  immunity,  as  a  rule,  after  a  few  years  of  Hfe  in  these 
regions.  Among  prophylactic  methods  should  be  included  the 
ability  to  make  an  accurate  diagnosis  of  the  complaint,  and  to 
recognize  the  plasmodium  in  blood  submitted  for  examination. 
After  diagnosis  the  patient  should  be  isolated,  if  possible,  in 
some  place  where  malarial  mosquitoes  do  not  exist,  for  he  is 
otherwise  liable  to  be  bitten  by  infected  mosquitoes,  and  thus  to 
become  the  subject  of  contemporaneous  infection  by  various 
different  malarial  parasites.  Moreover,  mosquitoes  which  feed 
upon  him  are  capable  of  disseminating  the  disease;  for,  by  reason 
of  the  sexually  developed  parasites  in  his  own  blood,  he  i'i  a 
source  of  infection  to  uninfected  mosquitoes,  and  consequently 
to  man.  He  should  also  be  energetically  treated  with  quinine, 
which  rapidly  destroys  the  parasite  in  the  blood.  The  pro- 
phylactic measures  are  directed  towards  the  protection  of  the 


5l8  HYGIENE  AND  PUBLIC  HEALTH 

infected  person  from  mosquitoes,  the  protection  also  of  the 
non-infected,  and  the  destruction  of  the  larvae  in  the  water. 
For  this  latter  purpose  kerosene  appears  to  be  efficient,  if  rightly 
used.  The  kerosene  acts  mechanically  by  asphyxiating  the 
larvae  and  nymphae,  which  float  flat  with  their  breathing  tubes 
on  the  surface  of  the  water;  it  must  therefore  form  a  stratum, 
covering  the  whole  surface  of  the  water.  The  most  suitable 
time  for  destroying  the  larvae  is  the  winter  or  the  beginning  of  the 
spring,  when  they  are  fewest  in  number  in  the  water,  and  new 
generations  have  not  yet  made  their  appearance.  Approximately 
I  oz.  of  the  oil  to  every  fifteen  square  feet  of  surface  is  sufficient. 

Among  the  odours  which  are  obnoxious  to  the  mosquito  are 
turpentine,  menthol,  and  garlic;  among  the  fumes,  tobacco  and 
simple  wood  smoke;  among  the  gases,  the  most  practical  and 
efficacious  destructive  agent  is  sulphurous  acid. 

In  malarial  districts  an  effort  should  always  be  made  to  pro- 
tect the  body  against  the  bites  of  all  proboscidian  insects,  especi- 
ally at  night,  by  means  of  veils,  gloves,  and  mosquito  curtains, 
or  by  inunction  of  the  skin  with  oil  or  liniment  containing  camphor 
or  eucalyptol.  It  should  be  a  rule  not  to  go  out  of  doors  after 
sunset,  and  suitable  clothing  should  be  worn  to  protect  the 
body  from  chills.  Since  Anopheles  larvae  are  mostly  found  in 
stagnant  pools  containing  algae,  all  such  pools  should  be  filled 
in,  drained,  or  otherwise  dealt  with,  so  as  to  permit  of  no  place 
remaining  where  the  mosquitoes  can  deposit  their  eggs.  The 
same  remarks  apply  to  tanks,  cisterns,  water  butts,  refuse  tins, 
etc.,  which  are  very  frequently  the  breeding  places  of  mosquitoes. 

All  the  old  observations  regarding  malaria  can  now  be  ac- 
counted for,  and  their  real  significance  understood.  Thus  it  is 
an  old  theory  that  malarial  miasm  rises  from  stagnant  water,  that 
malarial  outbreaks  depend  on  rainfall,  that  they  can  be  obliter- 
ated by  drainage  of  the  soil,  and  that  they  are  often  due  to 
disturbance  of  the  soil — all  of  these  being  factors  which  determine 
the  existence  of  puddles  affording  suitable  breeding  grounds 
for  Anopheles.  Old  observers  have  also  noted  that  malaria 
is  most  likely  to  be  contracted  about  sunset  and  at  night,  that 
the  "  miasm  "  did  not  extend  to  any  great  elevation  above  sea- 
level,  and  was  not  carried  by  high  winds.  These  facts  are  all 
explained  by  the  mosquito  theory  of  infection,  for  the  insects 
issue  forth  at  sunset,  and  pursue  their  search  for  food  through 
the  night,  never  mounting  high  in  the  air,  and  avoiding  windy 
or  stormy  nights. 


COMMUNICABLE    DISEASES  5^9 

Yellow  Fever, 

This  is  a  specific  disease  with  an  incubation  period  of  from  two 
to  six  days. 

Like  malaria,  yellow  fever  is  propagated  by  a  mosquito, 
but  the  species  is  known  as  Stegomyia  fasciata.  The  organism 
transmitted  to  man  by  the  bite  of  the  mosquito  has  not  yet 
been  identified.  It  appears  to  be  so  minute  as  to  be  ultra- 
microscopic;  but  it  undoubtedly  exists  in  the  blood  of  those 
affected,  although  only  in  a  state  capable  of  being  retransferred 
to  the  mosquito  during  the  first  three  or  four  days  of  the  disease, 
as  it  is  only  mosquitoes  that  have  fed  on  patients  during  the  first 
three  days  of  the  fever  that  are  found  to  be  infective.  The 
organism  evidently  undergoes  some  developmental  process  in 
the  mosquito,  as  it  is  found  that  it  is  not  until  fourteen  days  have 
elapsed  after  feeding  on  yellow  fever  blood  that  the  insect  is 
capable  of  conveying  infection  to  healthy  men.  This  infective 
power  it  retains  for  at  least  fifty-seven  days. 

The  preventive  measures  are  very  much  the  same  as  those  for 
malaria,  but  quinine  is  useless  as  a  prophylactic. 

Malta  or  Mediterranean  Fever. 

This  is  a  disease  of  often  very  prolonged  duration,  made  up 
of  a  series  of  febrile  attacks,  with  intervals  of  freedom  or  com- 
parative freedom  from  attack.  The  disease  is  due  to  an  organism, 
the  Micrococcus  melitensis,  which  is  found  in  the  spleen,  but  not 
in  the  general  circulation,  and  is  therefore  of  little  direct  use  in 
diagnosis.  The  disease  is  readily  conveyed  by  inoculation,  but 
does  not  appear  to  be  directly  communicable  from  the  sick  to 
the  healthy  by  infected  discharges,  fomites,  or  other  channels 
of  infection.  The  Micrococci  melitensis  are  readily  agglutinated 
by  the  serum  of  those  affected  with  the  disease,  and  this  fact  is 
a  great  aid  in  diagnosis.  The  Commission  appointed  to  in- 
vestigate the  disease  in  Malta,  reported  that  Maltese  goats  may 
harbour  the  micrococcus,  and  that  their  milk  may  be  infected 
with  the  organism.  Goat's  milk  is  the  common  source  of  supply 
in  Malta,  and  it  has  been  estabhshed  by  the  work  of  the  Com- 
mission that  in  Malta  these  animals  are  the  chief,  if  not  the  only 
means,  by  which  the  disease  is  spread.  The  micrococcus  is 
found  in  the  excreta  of   goats,   and.  the  udders  may  become 


520  HYGIENE   AND   PUBLIC   HEALTH 

infected  by  infected  excretions  or  soil,  but  the  animals  them- 
selves may  exhibit  no  signs  of  any  illness. 

The  discovery  as  to  the  part  played  by  goat's  milk  in  the 
transmission  of  the  disease  was  made  in  igo6,  and  since  that  year 
the  use  of  goat's  milk  has  been  prohibited  in  mihtary  and 
naval  barracks  in  Malta.  In  the  British  army  in  Malta  in  1905 
there  were  643  admissions  to  hospital  for  Malta  fever,  in  1906 
(when  the  prohibition  began  to  take  effect)  there  were  161 
admissions,  in  1907  11  admissions,  and  in  1908  7  admissions. 
Not  only  goat's  milk,  but  also  cow's  milk  is  now  prohibited,  as 
the  latter  animals  have  been  shown  to  be  liable  to  contract  the 
disease,  and  to  be  as  dangerous  as  goats.  The  result  of  the 
administrative  procedure  of  1906  has  practically  been  to  ex- 
terminate Malta  fever  as  a  cause  of  sickness  and  invaliding  in 
the  British  army. 

Leprosy. 

Although  leprosy  is  almost  certainly  the  result  of  the  intro- 
duction into  the  body  in  some  way,  not  clearly  understood,  of  a 
specific  organism — the  Bacillus  leprce — yet  some  doubt  still  exists 
as  to  whether  this  disease  is  ever  conveyed  by  direct  or  indirect 
communication  between  the  sick  and  the  healthy.  The  wives, 
husbands,  or  parents  of  leprous  patients,  who  have  elected  to 
be  segregated  with  them  on  the  Island  of  Molokai — one  of  the 
Hawaiian  group — do  not  appear  to  succumb  to  the  disease  in 
any  exceptional  proportion  as  compared  with  the  general  popu- 
lation of  the  islands.  Dr.  Ashburton  Thompson's  recent  investi- 
gation into  the  subject  supports  the  view  that  "  the  vast  majority 
of  instances  of  apparent  spread  of  leprosy  by  infection  are  spoilt 
by  having  been  observed  on  areas  of  recognized  endemicity,  so 
that  the  influence  of  locality  cannot  be  excluded.  ..."  It  seems 
probable  that  leprosy  enters  the  system  by  way  of  the  upper 
respiratory  tract;  but  it  is  possible  that  fleas,  etc.,  may  inoculate 
the  disease. 

Bcri-beri. 

Beri-beri  is  a  disease  of  wide  distribution.  It  is  occasionally 
to  be  seen  in  our  docks  amongst  the  crews  of  ships  arriving  from 
the  tropics,  but  is  more  especially  a  tropical  disease.  It 
occurs  generally  in  limited  epidemics,  in  particular  houses, 
institutions,  plantations,  mines,  etc. ;  but  it  may  spread  over 
large  areas,  only  attacking,  however,  limited  foci  in  such  areas. 


COMMUNICABLE   DISEASES  521 

The  case  mortality  ranges  from  5  to  50  per  cent.  (Manson). 
There  is  no  evidence  that  it  is  communicable  from  man  to  man. 

The  disease  is  characterized  by  difficulties  of  movement,  often 
attended  with  some  atrophic  paralysis  (more  particularly  of  the 
limbs),  by  disorders  of  sensation,  oedema  of  the  skin,  and  dropsy 
of  the  serous  cavities.  There  are  several  types  of  the  disease; 
in  one  the  nervous  symptoms  predominate,  in  another  the 
respiratory  system  is  most  affected,  and  in  a  third  (oedematous 
type)  the  circulatory  organs.  The  disease  is  essentially  a  chronic 
one,  and  it  is  said  that  dirt,  dampness,  and  overcrowding 
predispose  to  it.  Possibly  patients  with  open  wounds  may 
infect  others,  but  the  disease  does  not  appear  to  be  communicable 
in  any  other  sense.  Many  ascribe  a  food  origin  to  the  disease 
(viz.,  a  poison  which  develops  in  stale,  uncured  rice),  and  it  has 
been  shown  that  a  change  of  food,  the  administration  of  fat  and 
a  liberal  diet  containing  nitrogenous  food  are  valuable  in  arrest- 
ing symptoms.  This  disease  is  liable  to  be  mistaken  for  alcoholic 
or  arsenical  neuritis,  malarial  cachexia,  pellagra,  scurvy  and 
pernicious  anaemia. 

In  1897  Eykman  discovered  that  birds,  when  fed  on  polished 
rice,  developed  a  disease  analogous  to  beri-beri  with  extensive 
polyneuritis,  and  that  this  disease  was  not  induced  when  the 
birds  were  fed  with  unpolished  rice.  In  1906  Eykman  showed 
that  the  aqueous  extract  of  rice  polishings  cured  polyneuritis, 
and  that  the  active  constituent  in  the  extract  was  dialyzable 
and  soluble  in  alcohol. 

Fraser  and  Stanton  are  of  opinion  that  beri-beri  is  associated 
with  the  consumption  of  white  rice  as  the  staple  food,  such 
rice  having  lost  substances  in  the  process  of  milling  which  are 
essential  for  the  nutrition  of  nervous  tissue.  These  substances 
exist  in  adequate  amount  in  the  original  grain,  and  in  super- 
abundant quantity  in  the  polishings  from  white  rice.  The 
prevention  of  the  disease  will  be  achieved  by  substituting  for 
ordinary  white  milled  rice,  an  unshelled  rice  in  which  the 
polishing  process  has  been  omitted;  or  by  the  addition  to  a 
white  rice  diet  of  articles  rich  in  those  substances  in  which  such 
rice  is  deficient. 

It  is  now  generally  held  that  amongst  people  whose  diet  con- 
sists entirely,  or  almost  entirely,  of  rice,  beri-beri  is  due  to  the 
use  of  polished  rice,  the  polishings  containing  a  nitrogenous 
substance  which  is  essential  in  the  metabolism  of  the  nervous 


522  HYGIENE   AND    PUBLIC    HEALTH 

system.  This  "  antineuritic  "  substance  appears  to  be  a  pyri- 
midine  base,  but  its  exact  nature  is  not  known.  It  may  act  as 
an  activator  or  catalyst  in  metabolism,  thereby  rendering  possible 
the  assimilation  of  certain  nutrients,  possibly  phosphorus  com- 
povmds.  Beri-beri  amongst  people  who  are  not  rice  eaters  is 
probably  due  to  the  absence  from  the  food  of  this  same  anti- 
neuritic substance.  Norwegian  ship  crews,  who  are  now  fed  on 
wheaten  bread,  tinned  meat,  and  cooked  fish,  occasionally  de- 
velop the  disease,  whereas  when  the  diet  consisted  of  salt  meat, 
peas,  and  biscuits  made  with  rye  flour,  they  did  not  do  so. 

Dengue. 

This  specific  febrile  disease  is  peculiar  to  warm  climates,  and 
is  characterized  by  severe  muscular  and  articular  pains,  and 
sometimes  by  a  cutaneous  eruption.  It  is  especially  prevalent 
in  the  dry,  hot  seasons  of  very  warm  climates,  so  that  a  high 
temperature  is  doubtless  one  factor  which  determines  incidence. 
One  attack  is  generally  protective,  and  the  disease  spreads  by 
personal  communication. 

Filariasis. 

The  parent  filarise  {Filaria  Bancrofti)  are  long,  hair-like  trans- 
parent nematode  worms,  three  or  four  inches  in  length.  The 
two  sexes  live  together,  often  coiled  about  each  other,  and  are 
found  in  the  lymphatics  of  affected  men,  in  lymphatic  varices, 
and  sometimes  in  the  larger  lymphatic  vessels,  and  in  lymphatic 
glands.  The  diseases  which  the  adult  filariae  give  rise  to  are  of 
wide  distribution  in  the  tropical  and  sub-tropical  world,  and  are 
endemic  chyluria,  various  forms  of  lymphatic  varix,  probably 
tropical  elephantiasis  arabum,  and  other  obscure  tropical  affec- 
tions. The  worms  cause  obstruction  to  the  flow  of  lymph  in  the 
implicated  vessels,  and  the  lymphatic  areas  drained  by  these 
vessels  are  cut  off  from  the  general  circulation.  There  then 
follows  a  rise  of  pressure  in  the  occluded  lymphatics,  with  conse- 
quent varicosity  or  lymphatic  oedema,  or  a  combination  of  the 
two. 

After  fecundation  of  the  female  nematodes  by  the  males  new 
generations  of  embryo  filariae  are  poured  into  the  lymph.  These 
eventually  pass  into  the  general  blood  circulation  by  way  of  the 
thoracic  duct  and  the  left  subclavian  vein.  These  embryos 
{Filaria  nocturna)  are  minute,  transparent  worm-like  organisms. 


COMMUNICABLE   DISEASES  523 

about  „V  inch  in  length,  each  enclosed  in  a  delicate  sheath.  The 
filariae  are  only  found  in  the  peripheral  circulation  during  the 
hours  of  night.  During  the  day  they  retire  to  the  larger  arteries 
and  to  the  vessels  of  the  lungs  (Manson).  Should  the  females 
of  certain  species  of  mosquito  {Culex  fatigans)  feed  on  the  blood 
of  a  filariae-infected  man — which  they  do  almost  exclusively  at 
night  time — the  filariae  enter  the  stomach  of  the  mosquito.  Here 
the  filariae  escape  from  their  enclosing  sheaths,  and  swim  freely 
in  the  blood.  They  then  migrate  from  the  stomach  and  enter 
the  thoracic  muscles  of  the  mosquito,  where  they  develop  enor- 
mously— growing  to  tV  inch  in  length — and  acquire  a  mouth,  an 
alimentary  canal,  and  a  trilobed  tail.  They  next  quit  the  thorax, 
and  enter  the  head,  where  they  coil  themselves  up  close  to  the 
base  of  the  proboscis,  and  await  an  opportunity  to  enter  a  warm- 
blood  vertebrate  host,  when  the  mosquito  feeds  on  such,  and 
so  complete  the  cycle  of  their  existence.  In  man  the  periodic 
nocturnal  migrations  of  the  filariae  from  the  large  vessels  to  the 
peripheral  circulation  is  evidently  an  adaptation  to  the  nocturnal 
habits  of  the  mosquito,  so  as  to  secure  the  change  of  host  to 
the  mosquito  necessary  to  complete  the  cycle  of  existence,  and 
the  propagation  of  the  species. 

Sleeping  Sickness. 

The  Report  of  the  Commission  on  Sleeping  Sickness  in  Uganda 
shows  that  this  disease  is  caused  by  Trypanosoma  Ugandiense. 
This  organism  (flagellated  haematozoon)  is  a  minute,  colourless, 
transparent,  active  vermicule,  provided  with  a  long  flagellum 
at  its  anterior  extremity,  which  is  found  free  and  active  in  the 
liquor  sanguinis  of  those  affected  with  the  disease.  It  is  never 
seen  in  the  red  corpuscles.  The  trypanosomes  are  conveyed 
from  the  sick  to  the  healthy  by  the  tsetse  fly  and  not  by  other 
biting  flies.  Reproduction  of  the  trypanosomes  is  affected  in 
the  aHmentary  canal  of  the  tsetse  fly  by  longitudinal  division. 
The  trypanosomes  are  sexless. 

The  tsetse  fly  is  indigenous  to  the  equatorial  regions  of  Africa, 
which  are  known  as  "  fly-belts  " — i.e.,  those  regions  where  the 
fly  is  found  at  one  or  another  season  of  the  year.  One  species 
{Glossina  palpalis)  is  chiefly  concerned  in  the  transmission  of 
the  disease  known  as  "  sleeping  sickness,"  whilst  another  species 
{Glossina  morsitans),  although  now  beheved  to  act  occasionally 
as  a  carrier  of  sleeping  sickness,  is  best  known  as  the  cause  of 


524  HYGIENE    AND    PUBLIC   HEALTH 

spread  of  the  epizootic  South  African  cattle  disease  "  ngana," 
which  is  terribly  fatal  to  horses  and  cattle. 

Tsetse  flies  are  dull-coloured  brown  insects,  from  J  to  I  inch 
in  length.  When  at  rest  the  wings  are  closed  flat  one  over  the 
other  like  scissors,  and  this  is  a  character  which  serves  to  dis- 
tinguish glossina  from  all  other  blood-sucking  flies.  Tsetse  flies 
do  not  lay  eggs,  but  give  birth  to  a  yellow  larva,  which  burrows 
into  a  hole  to  undergo  its  developmental  changes.  The  fly  is 
chiefly  found  where  there  is  water — namely,  on  the  banks  of 
rivers  and  lakes,  where  they  abound  in  the  scrub  and  jungle. 

Trypanosomes  adhering  to  the  proboscis  of  this  fly  are  injected 
by  the  bite  under  the  skin,  and  are  thence  transferred  by  the 
lymphatic  vessels  to  the  lymphatic  glands,  which  become  swollen. 
Very  few  symptoms  of  illness  are  caused  so  long  as  the  trypano- 
somes are  confined  to  the  glands,  and  it  is  reported  that  at  one 
time  in  the  affected  parts  of  Uganda  from  50  to  75  per  cent,  of 
the  native  inhabitants  had  enlarged  glands  from  this  cause,  but 
were  able  to  carry  on  their  ordinary  avocations.  After  a  variable 
period  of  little  or  no  illness,  the  trypanosomes  spread  through 
the  blood  to  the  membranes  of  the  brain  and  spinal  cord,  when 
symptoms  of  lethargy,  intense  drowsiness,  emaciation,  tremors, 
and  exhaustion  ensue,  which  invariably  end  fatally. 

In  the  prevention  of  sleeping  sickness  it  is  important  to  recog- 
nize affected  individuals  in  the  early  stages  of  illness.  This  can 
be  done  by  withdrawing  with  a  hypodermic  syringe  some  fluid 
from  the  enlarged  glands,  when  the  trypanosomes,  if  present, 
can  be  readily  recognized.  An  attempt  should  be  made  to  isolate 
affected  individuals  in  a  camp,  but  this  is  clearly  impossible  if 
large  numbers  are  affected.  There  is  no  hope  of  exterminating 
the  fly.  The  removal  of  affected  populations  from  the  chief  fly 
areas  to  others  less  affected  has  been  tried,  but  without  success,  as 
it  has  been  found  that  the  flies  of  the  depopulated  areas  do  not  free 
themselves  from  trypanosome  infection,  even  after  a  lapse  of  two 
years.  It  seems  certain  now  that  the  trypanosomes  of  sleeping 
sickness  are  capable  of  being  harboured  in  other  vertebrate  hosts 
as  well  as  in  men. 

A  nkylostomiasis . 

This  is  an  endemic  anaemia,  which  is  very  prevalent  in  the 
tropics,  but  is  generally  known  in  Europe  as  "  miners'  anaemia." 
It  is  caused  by  a  parasitic  nematode  worm,  the  Ankylostoma 
duodenale,  whose  habitat,  as  its  name  implies,  is  the  small  in- 


COMMUNICABLE   DISEASES  525 

testine  of  man.  The  worms  attach  themselves  to  the  mucous 
membrane,  and  from  the  blood  obtain  their  nourishment.  The 
anaemia  produced  is  generally  ascribed  to  the  continued  small 
losses  of  blood,  but  another  theory  seeks  to  explain  the  anaemia 
as  the  direct  result  of  the  absorption  by  the  blood  of  toxic  sub- 
stances derived  from  the  parasite.  The  worms  measure  from 
6  to  15  mm.  in  length,  and  sexual  intercourse  between  males  and 
females  takes  place  in  the  intestine.  The  female  produces  an 
enormous  number  of  fertilized  eggs,  which  pass  out  in  the  faeces 
of  the  host.  The  embryos  pass  their  lives  in  mud,  earth,  or 
muddy  water,  and  may  be  transferred  to  man  either  by  means 
of  the  water  drunk,  or  by  soiled  food  or  hands,  when  they  pass 
at  once  into  the  digestive  tract;  or  they  enter  the  skin,  usually 
of  the  feet  or  legs,  gaining  access  to  the  lymphatic  vessels,  and 
later  to  the  subcutaneous  veins;  having  entered  the  circulation, 
they  reach  the  oesophagus,  stomach,  and  duodenum,  where  the}^ 
become  sexually  mature. 

The  disease  occurs  in  all  tropical  and  sub-tropical  countries, 
and  is  known  in  Southern  Europe  and  Belgium.  It  has  recently 
been  introduced  into  deep  Cornish  mines  in  England,  where  the 
depth  of  the  mine  ensures  a  relatively  high  temperature  of  the 
underground  workings.  It  is  undoubtedly  spread  in  mines  by 
miners  defaecating  underground  on  to  the  earth,  no  proper  system 
of  faecal  collection  and  removal  being  adopted,  or  fully  availed 
of  by  the  men,  if  provided.  A  diagnosis  is  best  made  by  an 
examination  of  the  fasces  for  the  ova  of  the  worm,  which  have 
a  regular  oval  form,  with  smooth  transparent  shell,  through 
which  two  or  four  light  grey  yolk  segments  can  be  seen.  The 
encapsuled  larvae  of  the  worm  may  live  in  water  for  a  year  or 
more,  and  they  are  very  resistant  to  most  disinfectants,  but 
creosote  kills  the  larvae  quickly,  and  a  solution  of  the  sulphate 
of  iron  is  also  valuable. 

Fortunately  the  large  majority  of  British  coal-mines  are  too 
cold  for  this  worm,  which  leads  to  a  condition  which  very  seriously 
incapacitates  the  infected  miners. 

Epizootic  Diseases. 
Anthrax. 

This  specific  disease  affects  cattle  most  frequently,  but  all 
animals  are  capable  of  being  infected.  The  infection  generally 
enters  the  body  through  the  alimentary  tract,  but  it  may  be 


526  HYGIENE    AND    PUBLIC    HEALTH 

introduced  through  the  respiratory  tract,  and  also  through  the 
skin  by  inoculation  (by  the  stings  of  insects,  through  abrasions, 
etc.).  When  the  soil  becomes  infected,  as  by  discharges  from 
animals,  the  disease  may  spread  rapidly  and  extensively  through 
herds.  Pasteur  and  others  have  held,  on  experimental  evidence, 
that  when  animals  dead  of  the  disease  are  superficially  buried, 
earth  worms  may  be  instrumental  in  conveying  the  specific 
organism  to  the  surface.  The  grass  may  become  extensively 
contaminated  by  discharges  from  sick  animals,  and  the  specific 
organism,  in  the  form  of  spores,  can  persist  for  considerable 
periods  in  decomposing  animal  and  vegetable  matter.  Animals 
feeding  on  infected  pastures  may  become  inoculated  through 
wounds  inflicted  on  the  buccal  mucous  membrane  and  the 
tongue  by  silicious  grasses,  probably  too,  by  swallowing  the 
spores  with  their  food.  The  disease  is  most  prevalent  on  warm, 
loose,  moist  soils,  rich  in  organic  matter,  especially  in  swampy, 
boggy  districts,  and  during  the  summer  months.  Animals  may 
also  be  infected  by  infectious  refuse  from  factories  where  hides, 
etc.,  are  dealt  with,  and  from  the  use  of  certain  manures  and 
imported  food  stuffs. 

Man  may  be  infected  from  the  hving  animal,  but  he  is  generally 
infected  during  the  process  of  kilhng  and  skinning  diseased 
animals,  and  possibly  by  eating  the  flesh.  In  this  country  the 
sorting  and  handling  of  wools,  hides  or  hair  (especially  horsehair 
from  Russia  and  China)  imported  from  abroad  is  most  frequently 
responsible  for  the  disease,  hence  the  popular  name  of  "  wool- 
sorter's  disease."  It  appears  that  the  blood-stained  wool  or 
hair  are  the  actual  carriers  of  the  germs  of  anthrax;  hence  the 
amount  of  blood  staining  is  a  rough  measure  of  the  danger  to 
the  operatives.  Man  is  infected  either  by  direct  inoculation 
of  a  wound  or  abrasion  on  the  face  and  hands,  arms,  and  legs, 
which  give  rise  to  the  malignant  pustule,  or  by  inhalation  of  dust 
containing  spores  into  the  mouth  or  lungs,  when  general  infection 
of  the  system  follows,  usually  proving  fatal  in  the  course  of  a 
very  few  days.  The  symptoms  of  general  infection  are  usually 
obscure,  and  appear  to  depend  upon  the  organ  with  which  the 
virus  first  comes  in  contact;  if  the  dust  is  swallowed,  the  stomach 
and  bowels  are  chiefly  affected;  if  inhaled,  the  lungs.  Bacilli 
are  found  in  the  serum  of  the  pustule,  and  in  the  blood  after 
death. 

Infection  through  the  alimentary  tract  is  rare.     In  man  it  is 


EPIZOOTIC   DISEASES  527 

much  more  common  for  the  disease  to  start  in  the  respiratory 
system,  the  lesions  being  found  in  the  trachea  or  bronchi,  and 
spreading  to  the  bronchial  and  other  thoracic  glands,  and  finally 
to  the  lungs.  In  the  lung  cases  many  bacilli  may  be  found  in 
the  local  lesions  in  the  chest,  but  few  are  found  in  the  other  organs 
or  in  the  blood,  until  just  before  death.  Bacilli  are  rarely  found 
in  the  secretions. 

The  disease  may  assume  the  following  types,  each  of  which 
is  also  met  with  in  man : 

1.  "Apoplectic":  Symptoms  of  cerebral  apoplexy  appear; 
the  animal  is  taken  suddenly  ill,  staggers,  and  falls,  and  dies  in 
convulsions  in  from  a  few  minutes  to  one  hour  at  most.  This 
is  the  most  usual  form  in  sheep  and  goats. 

2.  A  condition  of  excited  restlessness  is  followed  by  convulsions, 
stupor,  and  death,  as  if  from  apoplexy.  The  symptoms  last 
from  two  to  twenty-four  hours  in  this  form,  which  is  the  most 
usual  in  cattle. 

3.  "  Anthrax  fever  ":  This  is  the  most  common  form,  lasting 
from  twenty-four  hours  to  seven  days.  High  fever  and  frequent 
colic  are  followed  by  symptoms  similar  to  those  of  the  last  type, 
but  the  grave  symptoms  are  intermittent,  and  their  duration 
is  more  prolonged. 

4.  "  Carbuncular  disease":  Characterized  by  circumscribed 
cutaneous  swellings,  at  first  hard,  hot  and  painful,  and  later 
becoming  cold,  painless  and  with  a  tendency  to  slough,  but  not 
to  suppurate;  oedematous  swellings  of  the  skin;  similar  swell- 
ings on  the  mucous  membrane  of  the  mouth,  pharynx,  larynx, 
and  rectum;  irregular  fever ;-^  dyspnoea,  difficulty  in  swallowing; 
muscular  spasms.  This  form  generally  lasts  from  three  to  seven 
days,  and  is  very  fatal,  the  case-mortality  amounting  to  some 
25  per  cent. 

The  post-mortem  diagnosis  depends  upon:  (i)  The  discovery 
of  the  bacillus,  and  the  results  of  its  inoculation  into   mice; 

^  The  following  are  the  symptoms  of  fever  in  cattle:  The  temperature 
{per  rectum)  is  generally  about  41°  to  42°  C. ;  the  external  temperature  of 
the  body  is  unequally  distributed ;  the  hair  stands  on  end  and  loses  gloss ; 
feeding  and  rumination  are  suspended ;  great  depression ;  eyes  dull  and 
congested;  tongue  protruded;  often  diarrhoea;  short  panting  respira- 
tions; frequent  small  pulse  (60  to  120  per  minute) ;  nostrils  dry  or  covered 
with  foam;  in  cows,  secretion  of  milk  is  diminished  and  the  teats  are  hot; 
rigors. 

In  horses  the  symptoms  are  similar;  the  temperature  is  generally  about 
39-5°  to  41-5°  C,  and  the  pulse  from  80  to  100  per  minute. 


528  HYGIENE    AND    PUBLIC    HEALTH 

(2)  haemorrhages  of  variable  size,  often  evident  in  all  the  organs 
and  in  the  subserous,  submucous,  and  subcutaneous  tissues,  and 
serous  infiltration  and  congestion  of  organs  generally;  (3)  swell- 
ing of  the  spleen  to  from  two  to  five  times  its  normal  size: 
the  liver,  kidneys  and  lymphatic  glands  are  also  enlarged,  though 
to  a  less  degree;  (4)  a  tar-hke  condition  of  the  blood.  The 
bodies  are  often  well  nourished  ;  there  is  an  absence  of  rigor 
mortis ;  rapid  decomposition  sets  in,  and  where  there  is  consider- 
able oedema  there  may  be  wide  areas  of  necrosed  skin. 

In  this  disease,  as  in  some  others,  such  as  chicken  cholera, 
rabies,  and  swine  fever,  the  virus  can  be  attenuated  by  the 
various  methods  mentioned  on  page  417.  When  cultivated  at 
42°  C,  the  bacilli  of  anthrax  produce  no  spores,  and  the  intensity 
of  their  virulence  decreases  day  by  day.  This  attenuated  virus 
(or  it  may  be  the  waste  products  of  its  metabolism)  when  inocu- 
lated into  susceptible  animals,  inhibits  the  growth  of  the  specific 
microbes  when  introduced  into  the  body,  and  is  so  found  to 
confer  immunity  for  a  time  from  the  disease  in  its  virulent  form. 
The  same  result  can  be  attained  when  the  bacillus  from  one 
species  of  animal  is  passed  through  a  different  species.  If  the 
bacilli  of  sheep  or  cattle  are  inoculated  into  guinea-pigs  the 
organisms  taken  from  the  guinea-pig  are  attenuated  for  sheep 
or  cattle,  and  confer  immunity  from  subsequent  attack. 

Pasteur  used  two  vaccines  :  Vaccine  I.  grown  at  42°  C.  for 
twenty-four  days,  and  Vaccine  II.  grown  at  42°  C.  for  twelve 
days,  and  therefore  less  attenuated  than  Vaccine  I.  The  method 
as  used  for  sheep,  cattle,  and  horses  is  as  follows: — The  animal 
is  inoculated  with  Vaccine  I.  (5  drops  for  sheep,  10  for  cattle 
and  horses),  and  after  twelve  days  with  Vaccine  II.  Fourteen 
days  later  an  ordinary  virulent  culture  can  be  injected  without 
ill  effect,  and  the  animal  remains  immune  for  a  year  or  more  in 
many  cases. 

Quite  recently  mice  have  been  rendered  immune  against 
anthrax  virus  by  injection  of  an  albumose  (a  proteid  body) 
isolated  from  cultures  of  the  anthrax  bacilli,  of  whose  metabolism 
it  is  no  doubt  a  waste  product  (Hankin).  The  quantity  of  anthrax 
albumose  necessary  to  produce  immunity  is  extremely  minute. 

Sclavo's  anti-anthrax  serum  has  been  used  in  this  country 
during  the  past  few  years  with  encouraging  results. 

Sanitary  Precautions. — The  opening  of  bales  and  the  sorting 
of  hides  should  be  carried  out  in  special  well- ventilated  rooms 


EPIZOOTIC   DISEASES  529 

only  by  experienced  workmen,  and  by  those  whose  hands  and 
arms  are  quite  free  from  any  abrasion.  Handhng  should  be 
reduced  to  a  minimum,  and  any  suspected  wool  or  hides  should 
be  well  moistened  before  handling;  but  a  safer  procedure  would 
be  to  disinfect  all  bales  by  steam  under  pressure  prior  to  handling, 
although  this  is  liable  to  damage  them. 

Anthrax  is,  however,  the  most  protean  in  its  manifestations 
of  all  trade  diseases  and  the  most  difficult  to  control.  Disin- 
fection of  horsehair  by  steam  would  not  at  first  sight  seem 
difficult,  but  experiments  have  hitherto  shown  that  penetration 
into  hydraulically  pressed  bales  is  impossible,  and  that  even  when 
they  are  not  hydraulically  pressed  the  environment  of  the  spores, 
embedded  as  they  are  in  grease  and  dirt,  offers  a  great  obstacle 
to  successful  disinfection. 

However,  adequate  steam  disinfection,  provided  the  bales  are 
opened  and  the  horsehair  spread  out  (in  which  operation,  of 
course,  danger  is  incurred),  will  give  a  certain  guarantee  of  the 
destruction  of  the  anthrax  contagion.  The  soakage  of  hides  for 
twenty-four  hours  in  a  fluid  containing  i  per  cent,  of  formic  acid 
and  0-62  per  cent,  of  mercuric  chloride,  and  then  transferring 
them  to  the  ordinary  brine  pit,  is  also  recommended  for  hides. 

Mechanical  downward  exhausts,  actuated  by  a  fan,  should  be 
provided  beneath  the  sorting  benches  to  draw  away  the  dust, 
which  should  be  collected  in  a  washer  or  condenser.  The  water 
from  the  washer  should  be  well  boiled  before  it  is  emptied  down 
a  drain.  If  the  dust  is  collected  dry,  it  must  be  carefully  gathered 
together  and  burnt.  The  dust  must  not  be  allowed  to  reach  tlie 
external  atmosphere,  or  it  may  be  blown  long  distances  and 
infect  grazing  cattle.  It  is  during  the  "  carding  "  process,  when 
the  wool  is  torn  apart  by  high-speed  machinery  which  shoots 
particles  into  the  air,  that  most  cases  of  anthrax  infection  occur. 

The  premises  must  be  kept  clean ;  the  floor  of  the  sorting  room 
should  be  impermeable,  and  washed  down  with  disinfectant 
solution  daily. 

There  must  be  adequate  provision  of  air  space  and  ventilation. 

Dr.  Legge,  H.M.  Medical  Inspector  of  Factories,  suggests  the 
following  precautions  for  the  prevention  of  the  disease: — 

1.  That  all  workers  should  wear  overalls. 

2.  That  no  one  with  any  cut,  sore,  or  abrasion  of  the  skin, 
should  be  allowed  to  work  unless  he  can  be  absolutely  protected 
from  contamination. 

34 


530  HYGIENE   AND    PUBLIC    HEALTH 

3.  That  all  workers  should  wash  themselves  frequently,  and 
especially  before  taking  food. 

4.  That  all  cases  of  illness,  especially  if  connected  with  any 
swelling  or  boil,  should  be  immediately  intimated  to  the  manager, 
in  order  that  the  disease  may  be  attacked  in  its  earliest  stages, 
and  that  other  workers  similarly  exposed  may  be  warned  of  their 
danger. 

5.  That  the  bales  should  be  immediately  immersed  in  water, 
and  that  no  handling  of  the  raw  material  be  permitted  except 
in  the  wet  state.  This  will  prevent  dust,  and  the  risk  of  con- 
tagion then  will  only  be  possible  through  an  abrasion  of  the  skin. 
No  reliance  can  be  placed  on  protection  from  dust  by  the  use  of 
fans,  respirators,  or  currents  of  air.     The  germ  must  be  killed. 

6.  That  the  hair  should  be  boiled — say  for  thirty  minutes- — in 
order  to  cleanse  it,  and  soften  the  agglutinated  discharges  which 
may  contain  the  germs,  and  that  afterwards  steam  should  be 
applied  for  the  same  time  at  a  pressure  of  1-5  atmospheres. 
If,  however,  it  be  desired  to  effectually  disinfect  by  boiling,  with- 
out continuing  it  so  long  as  to  destroy  the  material,  it  could  be 
accomplished  by  using  a  2  per  cent,  solution  of  potassium  per- 
manganate, and  afterwards  bleaching  with  a  3  per  cent,  solution 
of  sulphurous  acid. 

7.  That  all  dust  and  residue  be  frequently  collected  and 
carefully  burned. 

By  the  Anthrax  Order  (1899)  of  the  Board  of  Agriculture, 
dung  and  other  litter  from  the  place  of  outbreak  are  to  be  burnt, 
or  disinfected  and  buried  to  the  satisfaction  of  the  inspector. 
Carcases  must  either  be  buried  in  lime,  with  the  skin  on,  as  soon 
as  possible  at  a  suitable  place  to  which  animals  will  not  have 
access,  and  at  a  depth  of  not  less  than  6  feet  below  the  surface; 
or  they  must  be  destroyed  by  exposure  to  a  high  temperature, 
or  by  chemical  agents  in  a  horse-slaughterer's  or  knacker's  yard, 
or  other  place  approved  for  the  purpose  by  the  Board.  A  carcase 
of  a  diseased  or  suspected  animal  shall  not  be  buried  or  destroyed 
otherwise  than  by  the  local  authoritj^  nor  be  removed  from  the 
farm  or  premises  upon  which  the  animal  died  or  was  slaughtered, 
except  for  the  purpose  of  being  buried  or  destroyed.  Before  a 
carcase  is  removed  for  burial  or  destruction,  all  the  natural 
openings  must  be  plugged  with  tow  or  other  suitable  material 
saturated  with  a  disinfectant,  in  no  case  shall  the  skin  of  the 
carcase  be  cut,  nor  shall  anything  be  done  to  cause  the  effusion 


EPIZOOTIC   DISEASES  531 

of  blood,  except  by  a  veterinary  inspector  and  for  the  purpose 
of  microscopical  investigation.  Disinfection  in  cases  of  anthrax 
shall  be  performed  by  the  local  authority  at  their  own  expense, 
and  shall  consist  in  thorough  sprinkhng  with  freshly  burnt  lime 
or  other  suitable  disinfectant,  and  subsequent  washing  with 
limewash  containing  in  each  gallon  4  ounces  of  chloride  of  hme, 
or  I  pint  of  commercial  carbolic  acid.  The  measures  applicable 
to  infected  fields  are  left  to  the  discretion  of  the  local  authority 
or  their  inspector. 

Under  the  Factory  and  Workshop  Act  (1901),  all  cases  of 
anthrax  occurring  in  factories  and  workshops  must  be  notified 
to  the  chief  inspector  of  factories. 

Tuberculosis  in  the  Lower  Animals. 

The  disease  is  characterized  by  nodular  deposits  (tubercles), 
frequently  translucent  and  hard,  and  about  the  size  of  a  millet 
grain,  which  cannot  be  shelled  out  from  the  surrounding  tissue. 

The  disease  is  most  frequently  found  in  cattle,  pigs,  and  birds, 
but  occasionally  in  all  warm-blooded  animals. 

The  symptoms  in  cattle  commence  insidiously,  and  are  as 
follows:  A  dry,  short,  jerky  cough;  increased  sensibihty  of  the 
chest  walls;  at  a  later  stage,  spasmodic  paroxysms  of  cough, 
especially  in  the  early  morning ;  percussion  sounds  dull  over  cir- 
cumscribed areas;  dyspnoea  (shown  by  the  extended  position  of 
the  head  and  neck);  diminished  secretion  of  milk;  flatulence; 
intermittent  colic,  with  alternating  diarrhoea  and  constipation; 
haematuria;  enlargement  of  glands;  irregular  fever;  excessive 
emaciation;  weakness;  often  peritonitis,  and  swellings  of  bones 
and  joints.  Animals  frequently  come  on  heat  and  remain  so 
for  a  long  time,  cows  mounting  their  fellows,  but  rarely  becoming 
fecundated  by  bulls;  and  pregnant  cows  frequently  abort. 
Brain  excitement,  convulsions,  paralysis,  staggers,  and  sudden 
collapse,  often  supervene  during  the  last  stages.  Tuberculosis  of 
the  udders  is  characterized  by  a  diffuse,  painless,  and  compara- 
tively firm  swelling,  usually  of  one  quarter  of  the  udder  (one  of 
the  posterior  quarters  as  a  rule) ;  the  milk  at  first  is  normal,  then 
becomes  thin  and  watery,  with  flakes,  and  generally,  though 
not  always,  the  specific  bacilh  are  present.  The  pudic  glands 
are  also  enlarged.  The  condition  differs  from  ordinary  mammitis 
or  garget,  by  the  gradual  increase  in  the  size  of  the  swelhng  and 
in  the  comparative  absence  of  pain  on  pressure. 


532  HYGIENE  AND  PUBLIC  HEALTH 

The  post-mortem  diagnosis  is  chiefly  made  from  the  Itmgs  and 
serous  membranes,  which  are  found  to  be  studded  with  the 
tubercle  nodules.  In  the  lungs  the  nodules  frequently  form 
grape-like  clusters  which  project  from  the  pleural  surfaces. 
The  lymphatic  glands  of  the  body  generally  are  often  enlarged 
and  affected  with  tubercles. 

According  to  the  experience  in  the  public  abattoirs  of  Germany, 
the  different  organs  are  affected  in  the  following  order  of  fre- 
quency: Lungs  75  per  cent,  of  all  the  cases,  visceral  pleura  55 
per  cent.,  peritoneum  48  per  cent.,  costal  pleura  47  per  cent., 
bronchial  and  mediastinal  glands  29  per  cent.,  liver  28  per  cent., 
spleen  19  per  cent. ;  no  other  part  of  the  body  is  affected  in 
more  than  10  per  cent,  of  the  cases,  and  the  udder  is  affected 
in  only  i  per  cent. 

In  pigs  the  starting  point  of  the  infection  is  generally  in  the 
intestines,  as  the  infection  is  almost  invariably  swallowed;  in 
cats  it  is  chiefly  in  the  lungs.  The  disease  is  sometimes  found 
in  goats,  and  therefore  the  popular  belief  that  goat's  milk  is  safe 
is  not  warranted.  In  birds  the  leading  symptoms  are:  Emacia- 
tion, pallor  of  the  mucous  membranes  of  the  eyes  and  mouth, 
loss  of  appetite,  vomiting,  diarrhoea,  swellings  of  joints,  tumours, 
and  sometimes  ulcers. 

In  applying  the  tuberculin  test  for  diagnostic  purposes,  the 
animal  is  first  allowed  to  become  cool  and  quiet;  then  the 
temperature  is  taken  per  rectum,  the  thermometer  being  allowed 
to  remain  in  for  five  minutes.  The  normal  temperature  of  bovine 
animals  ranges  from  38°  to  39°  C.  It  is  convenient  to  inject 
the  tuberculin  (35  to  45  minims  according  to  the  age  and  size  of 
the  animal)  into  the  neck  or  shoulder,  late  in  the  evening,  so  that 
the  observation  of  the  reaction  temperature  may  be  made  early 
next  day.  The  animal  must  not  be  regarded  as  certainly  tuber- 
culous unless  the  temperature  at  some  time  during  the  following 
day  shows  a  rise  of  at  least  i-2°  C.  above  that  of  overnight.  The 
rise  may  be  as  much  as  from  2-3°  C.  Animals  suffering  from 
advanced  tuberculosis  often  fail  to  show  a  marked  temperature 
reaction,  or,  if  they  are  already  feverish  (i.e.,  temperature  above 
39°  C),  the  reaction  may,  not  be  noticeable.  The  test  must  not 
be  repeated  until  at  least  a  month  has  expired,  as  the  animal 
will  often  not  react  again  in  a  less  period.  This  fact,  it  has  been 
suggested,  opens  the  door  to  fraud,  as  a  dishonest  salesman  could 
inject  his  animals  a  few  days  prior  to  sale,  and  then  sell  them  as 


EPIZOOTIC    DISEASES  533 

tuberculosis  free.  Those  animals  which  react  should  be  isolated, 
and  fattened  for  food,  if  the  disease  is  in  the  initial  stage  and 
strictly  localized  to  the  lungs. 

Under  the  Tuberculosis  Order,  191 3,  all  chronic  diseases  of  the  udder  in 
cows  must  be  notified,  if  in  the  form  of  indurations  or  suspected  tuber- 
culosis. Suspected  tuberculosis  with  emaciation  must  also  be  notified, 
even  if  the  udder  is  not  affected.  Notification  is  to  be  made  by  the  owner 
of  the  animal  to  a  constable  or  to  an  inspector  under  the  Contagious 
Diseases  Animals  Acts.  The  veterinary  inspector  under  the  Act  is  re- 
quired to  visit  the  farm  or  dairy  with  all  practical  speed,  and  determine 
if  the  animal  is  suffering  from  tuberculosis  of  the  udder,  if  it  is  giving  tuber- 
culous milk,  or  if  it  is  suffering  from  emaciation  with  tuberculosis.  He 
is  also  empowered  to  examine  any  other  animal  on  the  premises,  and  to 
apply  the  tuberculin  test  after  obtaining  the  written  sanction  of  the 
owner.  Power  of  entry  at  all  reasonable  times  is  given  to  the  veterinary 
inspector,  and  power  to  take  samples  of  milk,  as  considered  necessary. 
The  inspector  is  required  to  make  a  report  of  his  visit  to  the  local  authority. 
If  the  local  authority  is  satisfied  on  the  report  of  the  veterinary  inspector 
that  tuberculosis  exists  in  either  of  the  above  forms  (udder  disease  or 
tuberculosis  with  emaciation),  notice  is  to  be  given  in  writing  to  the  owner 
and  to  the  Board  of  Agriculture,  and  the  animal  must  be  slaughtered, 
unless  the  owner  has  given  notice  of  objection.  In  such  case  the  special 
authority  of  the  Board  of  Agriculture  must  be  obtained.  This  will  not 
be  given  if  the  value  of  the  animal  is  over  £t,o,  and  so  long  as  it  is  kept 
isolated  and  the  milk  dealt  with  as  directed  in  the  Order.  Compensation 
for  slaughter  of  diseased  animals  is  provided  for — namely,  three-fourths 
the  value  of  the  animal  if  tuberculosis  is  not  in  an  advanced  stage,  one- 
fourth  the  value  if  the  tuberculosis  is  advanced,  and  full  value  if  no  tuber- 
culosis is  present.  Milk  from  a  diseased  udder  must  not  be  mixed  with  other 
milk  until  after  a  veterinary  inspection  has  been  made.  Such  milk  must 
be  sterilized  by  heat  before  use,  and  all  vessels  used  for  its  reception  must 
be  sterilized. 

Actinomycosis. 

This  disease  affects  cattle  (especially  calves),  pigs,  horses,  sheep, 
and  man.  The  symptoms  are  of  long  duration,  and  include: 
Aversion  to  food,  because  of  pain  in  mastication ;  swollen  jaw  and 
tongue;  copious  salivation;  difficulty  of  swallowing,  and  dysp- 
noea, from  growths  in  the  pharynx  and  larynx;  swelling  of  the 
parotid  region,  which  is  covered  with  tumours  of  varying  size: 
later,  the  affection  of  the  cervical  vertebrae  causes  paralysis, and 
symptoms  resembling  phthisis  result  from  the  implication  of  the 
lungs. 

To  diagnose  this  disease  from  tuberculosis,  parotitis,  cellulitis, 
etc.,  the  nodules  and  abscesses  should  be  incised,  and  a  search 
made  for  the  ray  fungus. 

The  post-mortem  diagnosis  is  established  by  the  discovery  of 
tubercle-like  nodules  and  large  lobulated  tumours,  sometimes 
very  soft,  at  others  hard,  usually  in  the  upper  or  lower  maxillary 


534  HYGIENE    AND   PUBLIC   HEALTH 

bones.  These  consist  of  connective  tissue  stroma  with  numerous 
interspersed  nodules,  varying  in  size  from  a  millet  seed  to  a  pea. 
These  nodules  contain  the  sulphur-yellow  actinomycosis  granules, 
about  the  size  of  a  grain  of  sand;  they  may  develop  into  cold 
abscesses,  which  contain  the  small  yellow  tufts  of  the  fungus. 
MacFadyean  describes  these  nodules  in  animals  as  becoming 
hard  and  calcifying  like  tubercles,  but  rarely  forming  abscesses. 
On  the  sides  and  under-surface  of  the  mucous  membrane  of  the 
swollen  tongue  are  to  be  seen  rounded,  slightly  raised,  brown 
spots,  through  which  shine  very  minute  yellow  nodules.  In 
the  pharynx  there  are  generally  soft,  fungoid,  pedunculated 
growths  with  smooth  surfaces,  and  these  may  form  in  the 
oesophagus,  larynx,  and  trachea.  Elastic,  firm  nodules,  generally 
from  a  hazel  nut  to  a  man's  fist,  or  larger  in  size,  may  be  seen 
in  the  skin  and  subcutaneous  tissue,  chiefly  of  the  head  and 
neck.  The  lymphatic  glands  in  the  neighbourhood  of  the  neck 
are  generally  also  affected.  In  the  lungs,  disseminated,  firm, 
whitish-yellow  nodules  are  seen,  varying  in  size  from  a  millet 
seed  to  a  pea,  which  become  calcareous  in  the  centre;  or  there 
may  be  large  purulent  foci.  It  is  not  certain  if  the  disease  can 
be  communicated  to  man  b}^  contagion  or  infection,  or  by  eating 
the  infected  flesh. 

In  man  the  symptoms  are:  Abscesses,  chiefly  in  the  bones 
of  the  face  and  in  the  tongue.  The  liver,  lungs,  intestines,  and 
skin  may  also  be  the  seats  of  the  primary  lesion.  The  lungs, 
liver,  kidneys,  peritoneum,  intestines,  and  brain  may  become 
infected  by  metastasis.  Probably,  as  in  animals,  it  is  transmitted 
exclusivel}^  by  portions  of  plants,  which  are  studded  with  the 
fungi. 

Rabies. 

In  this  disease  the  virus  is  contained  in  the  saliva  of  rabid 
animals,  such  as  dogs,  wolves,  horses,  bovines,  cats,  pigs,  sheep, 
goats,  and  even  birds.  The  disease  is  spread  by  inoculation  into 
the  skin  through  the  bite  of  a  rabid  animal. 

The  incubation  period  in  dogs  is  from  three  to  six  weeks  on  an 
average,  with  a  minimum  of  a  few  days  and  a  maximum  of  several 
months.  The  symptoms  of  canine  rabies  assume  two  forms — i.e., 
the  "  furious  madness,"  which  is  the  more  frequent,  and  the 
"  dumb  madness."  The  symptoms  in  the  furious  form  follow 
each  other  in  three  stages:  (i)  The  melancholy,  (2)  the  irritative, 
and  (3)  the  paralytic.     Stage  i  generally  lasts  from  twelve  to 


KVlZnnTlC   DISEASES  535 

forty-eight  hours,  and  is  marked  by  capricious  appetite,  the 
animal  being  sullen,  nervous,  excited,  irritable,  and  distrustful; 
it  bites  at  everything,  and  often  swallows  foreign  bodies.  There 
is  sometimes  abnormal  itching  at  the  site  of  the  bite.  Stage  2 
lasts  three  or  four  days,  and  is  characterized  by  attacks  of  fury 
(which  may  continue  for  some  hours)  and  convulsions,  with 
remissions.  The  animal  is  very  irritable,  and  often  tries  to 
run  away;  it  shows  an  excessive  morbid  desire  to  snap,  and 
later  to  bite,  often  with  such  force  as  to  break  its  teeth.  The 
animal  does  not  try  to  bite  human  beings  unless  approached. 
Paralysis  of  the  vocal  cords  often  causes  a  change  in  voice. 
Hallucinations  are  more  prominent  than  mania.  In  Stage  3  the 
animal  is  much  emaciated,  the  hair  stands  on  end  and  is  rough, 
the  eyes  are  sunken  and  glassy,  and  the  power  of  swallowing 
is  lost  owing  to  paralysis  of  the  muscles  of  deglutition ;  paralysis 
of  the  lower  jaw  then  supervenes,  and  the  jaw  drops  down,  the 
tongue  hanging  out;  the  hind  quarters  next  become  paralyzed. 
The  whole  stage  is  attended  by  paroxysms  of  excitement,  which 
grow  less  and  less  frequent,  until  the  animal  dies  between  the 
fifth  and  tenth  day. 

Dumb  madness  differs  mainly  in  the  absence,  or  very  short 
duration,  of  stage  2. 

In  man  there  is  premonitory  pain  in  the  cicatrized  wound  from 
the  bite,  general  malaise,  swelling  of  the  neighbouring  lymphatic 
glands,  and  aversion  to  fluids.  In  the  second  stage  reflex  spasms, 
delirium,  and  mania  supervene,  the  spasm  affecting  chiefly  the 
throat  when  attempts  are  made  at  swallowing,  and  being  excited 
even  by  the  sight  of  water  or  the  thought  of  drinking;  there  is 
also  much  anxiety,  uneasiness,  and  thirst,  and  the  patient  slavers, 
because  of  the  inabihty  to  swallow  the  saliva.  The  third  stage 
is  characterized  by  paralysis  and  spasms,  and  death  supervenes 
in  from  two  to  four  days. 

Whilst  in  the  man  the  usual  period  of  incubation  after  the 
infliction  of  a  bite  by  a  rabid  dog  is  somewhere  about  six  weeks, 
it  may  be  as  short  as  six  days  or  as  long  as  two  years  (Horsley). 
The  rabid  virus  is  chiefly  contained  in  the  nervous  centres,  and 
it  is  presumed  that  the  disease  only  shows  itself  when  these 
centres  are  attacked  by  the  virus.  This  view  explains  the  unequal 
length  of  the  incubation  period  in  different  cases,  the  incubation 
period  being  governed  by  the  time  taken  by  the  virus  to  travel 
from  the  point  of  inoculation  up  to  the  central  nervous  system, 


536  HYGIENE    AND    PUBLIC   HEALTH 

and  for  its  development  therein.  If  the  virus  travels  up  the 
nerves  the  incubation  is  long,  but  if  conveyed  in  the  blood  stream 
the  incubation  may  be  very  short. 

Horsley  gives  the  death-rate  among  persons  bitten  by  in- 
dubitably rabid  dogs  as  on  the  average  about  15  per  cent. ;  that 
is  to  say,  about  85  per  cent,  of  the  persons  bitten  are  insus- 
ceptible, or,  at  least,  escape  the  action  of  the  virus,  for  rabies 
once  developed  is  almost  invariably  fatal. 

Pasteur  elaborated  a  system  of  treatment  by  protective 
inoculations,  which  has  proved  of  great  value.  Shortly,  it  may 
be  described  as  follows:  The  virus  from  the  central  nervous 
system  of  a  rabid  dog  or  wolf  is  inoculated  subdurally  into  a 
rabbit;  a  second  rabbit  is  similarly  inoculated  from  the  first,  a 
third  from  the  second,  and  so  on  until  a  virus  of  maximum 
intensity  is  obtained — killing  a  rabbit  in  seven  days.  The  spinal 
cord  of  a  rabbit  thus  killed  by  this  virus  is  submitted  to  a 
drying  process  (by  calcium  chloride),  at  a  temperature  of  25°  C, 
for  a  certain  number  of  days  (one  to  fourteen).  By  this  means 
the  virulence  of  the  virus  is  diminished  and  eventually  destroyed 
by  drying  for  fourteen  days.  The  person  undergoing  the  treat- 
ment is  inoculated  first  with  an  emulsion  of  a  cord,  which  has 
been  dried  for  fourteen  days ;  on  succeeding  days  he  is  inoculated 
with  cords  which  have  been  dried  for  thirteen,  twelve,  eleven,  etc., 
days;  and  finally  with  a  cord  which  has  been  dried  for  only  one 
day,  and  is  therefore  highly  virulent.  Persons  who  have  been 
bitten  by  indubitably  rabid  animals,  and  have  submitted  them- 
selves to  the  Pasteur  treatment  within  a  few  days  of  the  infliction 
of  the  bite,  have  almost  invariably  escaped.  The  death-rate, 
instead  of  15  per  cent,  in  the  unprotected,  is  only  1-36  per  cent. 
in  the  protected.  During  the  ten  years  1886-95,  the  mortality 
in  protected  persons  was  only  0-48  per  cent.  (Muir  and  Ritchie). 
For  the  more  dangerous  wounds  the  number  of  inoculations 
is  greater,  and  the  use  of  the  recent  "^cords  is  more  rapidly 
brought  into  operation.  This  is  the  "  intensive  "  treatment, 
which  is  used  in  severe  cases,  as  bites  on  naked  parts  and  wolf 
bites. 

In  this  country  rabies  is  spread  by  infected  dogs  Where 
muzzling  regulations  and  the  slaughter  of  stray  dogs  have  been 
enforced,  the  disease  is  rapidly  exterminated. 

The  diagnosis  of  the  earlier  symptoms  largely  depends  upon 
whether  proof  is  forthcoming  of  the  animal  or  man  having  been 


EPIZOOTIC    DISEASES  537 

bitten  by  a  rabid  animal.  The  post-mortem  changes  in  canine 
rabies  are  neither  constant  nor  specific;  but  the  following 
diagnostic  appearances  may  be  mentioned — emaciation,  dark 
blood,  hyperaemia  of  mucous  membranes  and  of  many  of  the 
internal  organs,  the  frequent  presence  of  foreign  bodies  in  the 
pharynx  and  oesophagus  or  the  stomach,  which  often  contains 
such  articles  as  straw,  hair,  feathers,  string,  wood,  or  pebbles, 
but  very  little  or  no  food.  Frequently  small  haemorrhages  arc 
seen  on  the  surface  of  the  gastric  and  buccal  mucous  membrane, 
and  the  intestines  are  generally  found  to  be  empty. 

Foot  and  Mouth  Disease. 

Foot  and  mouth  disease  is  peculiar  to  ungulates,  and  therefore 
occurs  chiefly  in  cattle,  sheep,  pigs,  and  goats;  but  all  wild 
rtmiinants  are  liable  to  it.     The  disease  is  rarely  fatal. 

The  symptoms  in  cattle  are:  Vesicles  and  ulcers  on  the  oral 
mucous  membrane,  and  on  the  skin  of  the  coronet  and  of  the 
interdigital  space  (sheep,  goats,  and  pigs  are  usually  affected  only 
on  the  feet).  The  small  yellowish-white  vesicles  on  the  gums, 
tongue,  buccal  mucous  membrane  and  lips  gradually  increase 
in  size,  until  they  become  as  large  as  a  five-shilling  piece, 
when  the  vesicles  burst,  leaving  ulcers.  There  is  much 
sahvation,  and  rapid  and  great  emaciation.  The  milk  is 
colostrum-like  in  appearance  and  taste;  and  in  milch  cows  the 
exanthem  often  spreads,  by  the  act  of  milking,  to  the  udders 
and  teats. 

There  is  often  violent  inflammation  of  the  udder,  with  sero- 
sanguineous  discharge ;  sometimes  ulcers  form  on  the  pharyngeal 
mucous  membrane,  and  there  is  dyspnoea  and  nasal  and  bronchial 
catarrh.  Occasionally  the  vesicles  form  on  the  skin  at  the  base 
of  the  horns,  also  on  the  vulva  and  vagina,  and  on  the  general 
surface  of  the  skin. 

As  regards  the  feet,  there  is  first  a  painful  swelling  of  the 
coronet,  especially  between  the  toes  and  towards  the  plantar 
cushions;  then  lameness  results.  Erysipelatous  inflammation 
sometimes  supervenes,  and  later  on  ulcers  and  abscesses;  as  a 
result,  the  hoofs  may  be  shed.  The  general  constitutional 
symptoms  are  those  of  pyaemia. 

In  the  malignant  type,  symptoms  supervene  resembling 
apoplexy,  and  the  animal  dies  suddenly  from  paralysis  of  the 
heart,  due  to  the  development  of  toxins. 


538  HYGIENE    AND    PUBLIC    HEALTH 

The  disease  may  be  transmitted  to  man  through  milk,  butter, 
and  cheese,  or  is  inoculated  through  wounds  in  the  hands  and 
arms.  The  symptoms  are:  Fever;  disturbance  of  digestion; 
vesicles  on  the  face  (lips  and  ears),  the  fingers,  the  arms,  the 
female  breasts,  and  the  mucous  membrane  of  the  mouth,  pharynx, 
and  conjunctiva;  abdominal  pains;  and  vomiting.  Occasionally 
death  supervenes  in  young  persons.  The  disease  is  not  conveyed 
by  eating  flesh.  A  few  outbreaks  have  been  reported  among 
infants  fed  upon  infected  cow's  milk. 

Glanders. 

Glanders  and  farcy  are  now  recognized  as  different  manifesta- 
tions of  the  same  disease.  It  is  essentially  an  equine  disease, 
affecting  horses,  donkeys,  and  mules;  but  it  may  be  transmitted 
from  horses  to  many  other  animals,  including  man,  by  direct 
inoculation.  In  some  years  the  disease  causes  a  considerable 
mortality  in  this  country  among  horses.  It  may  be  transmitted 
by  ingestion,  inhalation  and  inoculation. 

The  symptoms  may  be  those  of  either  acute  or  chronic  glanders. 
Acute  glanders  is  a  very  rapidly  progressive  specific  infective 
disease.  The  prominent  symptoms  are:  High  temperature; 
rigors;  muco-purulent  nasal  discharge,  which  later  becomes 
sanguineous,  the  visible  mucous  membrane  being  covered  with 
small  nodules  and  ulcers,  which  are  frequently  confluent  and 
covered  with  diphtheritic-like  sloughing  masses;  dyspnoea;  and 
roaring  inspirations.  There  are  also  oedematous  swellings, 
nodules,  and  ulcers  of  the  skin;  inflammation  of  the  lymphatic 
vessels  (especially  in  the  neighbourhood  of  the  head) ;  swelling 
and  suppuration  of  the  lymphatic  glands;  difficult  deglutition, 
diarrhoea,  and  rapid  emaciation.  This  form  is  invariably  fatal 
in  from  three  to  fourteen  days. 

Chronic  glanders  has  an  insidious  origin.  The  symptoms  are: 
Chronic  nasal  catarrh,  with  discharges,  which  later  become  less 
sticky  and  yellow,  and  temporarily  sanious,  these  haemorrhages 
from  the  small  ulcerous  erosions  being  frequently  the  first  visible 
sign.  Later  on  nodules,  and  finally  ulcers,  appear  on  the  nasal 
mucous  membrane,  and  swelling  of  the  submaxillary  glands 
follows.  Frequently  there  is  cough  and  dyspnoea,  and  generally 
some  irregular  fever;  wasting  is  marked;  and  in  the  late  stages 
there  may  be  oedematous  swellings  of  the  limbs,  abdomen,  and 
chest. 


EPIZOOTIC   DISEASES  539 

Glanders  of  the  skin  is  less  common  in  chronic  glanders  than 
in  acute,  the  favourite  sites  being  the  limbs,  shoulders,  breast, 
and  hypogastrium.  The  nodules  or  boils  ("  farcy  buds  ")  vary 
from  a  pea  to  a  walnut  in  size,  and  may  disappear  to  some 
extent,  although  they  generally  undergo  change  into  ulcers;  the 
efferent  lymph  vessels  are  swollen  into  knotted  cords,  the  heads 
of  which  often  become  ulcerated.  Affected  lymphatic  glands 
are  often  enlarged,  and  later  become  indurated  or  suppurate. 

In  man  the  disease  is  set  up  by  direct  inoculation  of  the  in- 
fected secretions,  usually  into  an  abrasion  of  the  skin.  The  parts 
usually  infected  are  the  hands,  the  nasal  mucous  membrane, 
the  lips,  and  conjuctivae.  Infected  parts  become  swollen 
and  painful,  and  the  lymphatics  inflamed;  there  is  fever;  nasal 
discharge;  ulcers  on  the  nasal  mucous  membrane;  pustules  and 
abscesses  in  the  skin ;  ulcers  in  the  mouth,  pharynx,  and  larynx, 
and  on  the  conjunctiva;  articular  swellings  are  often  present; 
and  sometimes  intense  gastro-enteritis.  Death  may  ensue  in 
from  a  fortnight  to  a  month,  or  the  disease  may  become  chronic. 
The  fatality  is  great  unless  the  disease  is  strictly  localized,  and 
is  treated  early  by  cauterization. 

A  horse  showing  no  outward  symptoms  of  the  disease  may  be 
glandered,  and  a  source  of  infection  to  others.  The  diagnosis 
is  assisted  by  the  inoculation  of  other  animals  (field  mice  and 
guinea-pigs)  for  the  observance  of  symptoms,  and  by  the  injection 
of  "  mallein."  Recently  too  the  Widal  reaction  has  been  used 
to  diagnose  the  disease. 

"  Mallein  "  is  a  preparation  made  from  the  bacilli  of  glanders 
in  a  manner  analogous  to  tuberculin.  It  is  injected  subcutane- 
ously  at  the  base  of  the  neck,  after  the  animal's  temperature  has 
been  taken.  The  increase  in  temperature  within  twelve  hours 
should  exceed  2°  C.  for  a  certain  diagnosis,  and  i-2°  C.  to  warrant 
suspicion.  There  is  also  a  large  painful  swelling  at  the  site  of 
inoculation  (in  the  horse),  and  a  swelling  of  the  farcy  buds. 

The  preventive  measures  which  should  be  taken  against  the 
disease  have  generally  been  restricted  to  those  embodied,  in 
1892,  in  an  Order  of  the  Board  of  Agriculture.  That  Order 
provided  for  compensation  for  slaughter  of  affected  and  suspected 
animals,  and  certain  powers  were  given  for  securing  the  ex- 
amination of  horses  by  veterinary  surgeons,  and  for  controlling 
the  disease  when  discovered.  Dead  bodies  were  ordered  to  be 
buried  6  feet  deep  in  their  skins,  and  covered  with  a  sufficient 


540  HYGIENE    AND    PUBLIC    HEALTH 

quantity  of  quicklime  or  other  disinfectant ;  or  the  local  authority 
was  empowered,  with  the  consent  of  the  Board,  to  have  the  body, 
which  had  been  disinfected  prior  to  removal,  cremated  or  treated 
by  chemical  agents. 

Complete  measures  of  prevention  and  stamping  out  would 
include:  (i)  A  systematic  and  repeated  inspection  of  horses  in 
affected  localities,  and  the  employment  of  "  mallein  "  for  diag- 
nostic purposes ;  (2)  the  avoidance  of  common  drinking  troughs ; 
(3)  the  prompt  separation  of  all  suspected  horses  and  the  slaughter 
of  all  diseased  ones;  (4)  the  prompt  cleansing  and  disinfection 
of  infected  premises;  and  (5)  newly  purchased  horses  to  be 
quarantined  before  being  introduced  into  a  stud. 

A  Departmental  Committee,  which  reported  on  glanders  in 
1899,  made  the  following  recommendations: 

1.  That  the  Board  of  Agriculture  should  exercise  a  more 
extended  supervision  of  the  working  of  the  Glanders  or  Farcy 
Order. 

2.  That  notification  should  be  made  either  to  a  constable  or 
to  a  veterinary  inspector. 

3.  That  where  practicable  the  local  veterinary  inspector  should 
not  engage  in  private  practice. 

4.  That  it  should  be  made  obligatory  for  veterinary  surgeons 
to  notify  cases  of  glanders  of  which  they  become  aware. 

5.  That  occupiers  or  owners  of  knackers'  yards  should  notify 
any  case  of  glanders  found  in  animals  taken  to  their  yards  for 
slaughter. 

6.  That  horses  that  react  to  the  "  mallein  "  test  should  be 
considered  as  possible  sources  of  infection. 

7.  That  horses  that  the  veterinary  inspector  may  consider  to 
have  been  exposed  to  contagion  should  be  dealt  with  in  the  same 
manner  as  suspected  horses,  but  with  certain  reservations. 

8.  That  the  slaughter  of  all  animals  showing  clinical  symptoms 
of  glanders  should  be  made  compulsory. 

9.  That  compensation  for  horses  slaughtered  solely  on  account 
of  reaction  to  the  "  mallein  "  test  should  be  on  a  higher  scale 
than  that  for  a  "  clinically  "  diseased  horse. 

Many  of  the  foregoing  recommendations  have  been  adopted 
in  the  Glanders  or  Farcy  Order  of  1907. 


EPIZOOTIC   DISEASES  541 

Variola, 

Variola  occais  in  most  of  the  domestic  animals.  Cow-pox 
(variola  in  the  cow)  was  first  experimentally  transmitted  to  man, 
in  1796,  by  Jenner,  who  proved,  in  1798,  that  it  conferred  im- 
mmiity  from  small-pox.  The  close  relationship  existing  between 
the  various  kinds  of  variola  found  in  man  and  other  animals  is 
proved  by  their  reciprocal  power  of  conferring  immunity.  Cow- 
pox  in  man  is  protective  against  small-pox,  and  the  latter  is  also, 
protective  against  the  former. 

The  symptoms  of  variola  in  animals  (which  appear  after  an 
incubation  period  of  about  a  week)  are  divided  into  several 
stages:  (i)  The  prodromal  stage,  which  lasts  a  day  or  two,  is 
characterized  by  fever,  catarrhal  affection  of  the  mucous  mem- 
branes, and  erythema  of  the  skin;  (2)  in  the  eruptive  stage, 
lasting  from  six  to  eight  days,  red  spots  suddenly  appear,  which 
become  nodules  of  the  size  of  a  pin's  head,  surrounded  by  a  red 
ring,  and  which  after  a  few  days  form  bluish-white  vesicles,  often 
with  a  depression  in  the  centre;  (3)  in  the  stage  of  suppuration, 
which  lasts  two  or  three  days,  the  vesicles  become  pustules,  and 
the  temperature,  which  had  fallen  during  the  eruptive  stage, 
again  rises;  (4)  in  the  stage  of  exsiccation,  which  lasts  from  three 
to  five  days,  the  pustules  dry  up  into  yellowish,  and  later  on  into 
dark  brown  crusts  or  scales,  which  fall  off,  leaving  shining  red 
cicatrices. 

Sometimes  the  eruption  is  confluent,  and  the  type  of  the 
disease  may  also  be  haemorrhagic. 

Cow-pox  chiefly  attacks  young  cows,  the  eruption  being 
generally  confined  to  the  teats  and  udder;  fever  is  absent  or 
slight;  and  the  prognosis  is  very  good.  The  disease  spreads 
slowly  in  a  shed  from  animal  to  animal,  and  the  eruption  lasts 
altogether  about  twenty-one  days. 

The  lymph  of  cow-pox,  or  "  vaccine,"  was  introduced  for 
vaccination  in  man  by  Jenner  in  1798.  As  cow-pox  is  com- 
paratively rare,  "  humanized  "  vaccine,  or  vaccination  from  man 
to  man,  was  subsequently  employed;  but  owing  to  the  drawbacks 
attending  this  practice,  animal  vaccination  has  been  recently 
reintroduced.  For  the  cultivation  of  the  vaccine,  calves  three 
to  six  months  old  are  taken,  the  skin  over  the  lower  part  of  the 
abdomen  is  shaved  and  disinfected,  and  the  lymph  from  a 
previously   vaccinated  calf  is  inoculated.     Vesicles  mature  in 


542  HYGIENE   AND   PUBLIC   HEALTH 

from  four  to  five  days,  and  the  lymph  collected  from  these  is  used 
for  human  vaccination  or  for  the  further  inoculation  of  calves. 
One  calf  yields  from  i,ooo  to  3,000  doses  of  lymph.  The  vaccine 
may  be  preserved  in  (i)  capillary  tubes,  in  which  it  loses  strength 
and  becomes  inert;  or  (2)  it  may  be  kept  in  the  drj^  condition  by 
scraping  off  the  lymph  and  crusts,  drying  them,  and  then  placing 
them  between  two  glass  slides  and  sealing  with  paraffin — ^the 
vaccine  then  keeps  for  months;  or  (3)  it  may  be  rubbed  down 
with  glycerine  and  preserved  in  capillary  tubes. 

Scarlet  fever  is  said  to  affect  the  lower  animals,  but  this  is 
probably  due  to  a  confusion  of  the  disease  with  petechial  fever — 
a  disease  characterized  by  haemorrhages  in  the  skin  and  internal 
organs,  such  haemorrhages  in  the  skin  varying  in  size  from  a  pea 
to  a  half-crown  piece. 

Scarlet  fever  in  man  has  probably  no  sort  of  relation  with 
any  disease  of  cows.  Klein's  statements  as  to  the  relationship 
between  human  scarlet  fever  and  a  bovine  eruptive  fever  have 
never  been  confirmed,  and  cows  have  been  proved  to  be  immune 
to  human  scarlet  fever  (Crookshank,  MacFadyean,  Edington, 
McCall,  Axe,  and  others). 

Bubonic  plague  may  affect  rats,  pigeons,  mice,  cats,  monkeys, 
and  pigs;  and  flies,  fleas,  and  mosquitoes  may  communicate  the 
disease. 

The  cholera  of  birds  (fowl  typhoid) ;  swine  erysipelas,  swine 
fever  or  hog  cholera  ;  epidemic  pleuro-pneumonia  in  horses,  bo  vines, 
and  goats;  cattle  plague,  splenic  apoplexy,  and  quarter  ill,  have 
not  been  shown  to  be  communicable  to  man. 

Whether  the  dysentery  of  cattle  and  domestic  animals,  the 
influenza  of  horses,  asses  and  mules,  and  the  diphtheria  of 
birds,  calves  and  pigs,  are  etiologically  identical  with  the 
similarly  termed  diseases  in  man  is  at  present  unknown,  but 
the  balance  of  evidence  is  opposed  to  such  a  view.  The  disease 
called  "  thrush  "  in  human  beings  is  found  in  calves,  foals,  and 
birds,  and  is  due  to  the  same  fungus. 

The  Piroplasmoses. 

This  term  embraces  a  number  of  distinct  infective  diseases, 
the  causative  agent — a  piroplasma — being  transmitted  from  one 
animal  to  another  through  the  agency  of  ticks.  The  piroplasmata 
are  protozoa.     They  are  pea-shaped  micro-organisms,  and  are 


EPIZOOTIC    DISEASES  543 

fouiul  singly,  or  in  pairs,  or  in  multiples  of  pairs  within  the  red 
blood  corpuscles  of  an  infected  animal.  Larger  sausage-shaped 
extracorpuscular  parasites  are  also  described  by  Nuttall,  which 
he  thinks  may  be  gametes,  as  they  resemble  the  malarial  crescents 
of  human  blood.  The  diseases  caused  by  piroplasmata  are 
Texas  fever  (Redwatcr  of  cattle),  Rhodesian  fever  (cattle),  and 
Carceag  (European  sheep).  There  is  also  piroplasmosis  of  the 
dog  (South  Africa),  horse,  donkey,  and  mule  (South  Africa), 
monkey  (Uganda),  and  Rocky  Mountain  fever  in  man,  which  is 
also  probably  due  to  piroplasma  infection.  In  Brazil  fowls  are 
apt  to  suffer  from  spirochaete  disease,  which  is  a  tick-transmitted 
infection,  the  spirocheete  greatly  resembling  the  spirillum  of 
relapsing  fever  in  man. 

All  these  diseases  commence  with  fever,  followed  by  a  great 
destruction  of  blood-corpuscles  by  the  piroplasmata,  and  the 
serum  becomes  tinged  with  haemoglobin,  which  finds  its  way  into 
the  urine.  Haemoglobinuria  and  icterus  are  the  usual,  but  not 
invariable,  symptoms.  Manson  has  pointed  out  the  similarity 
between  the  piroplasmoses  and  blackwater  fever  of  man,  as 
regards  the  characteristic  symptoms  —  haemoglobinuria  and 
icterus,  the  latter  disease  being  usually  regarded  as  a  manifesta- 
tion of  malaria.  Immunity  from  a  fresh  attack  follows  upon 
recovery  in  piroplasmosis,  but  the  immunity  appears  to  be  due 
to  the  fact  that  the  parasites  persist  for  long  periods  in  the  blood 
of  recovered  animals,  although  not  demonstrable  microscopically. 
Consequently,  such  animals  may  be  the  means  of  propagating 
infection  indefinitely  in  tick-infected  countries. 

The  ticks,  which  are  the  carriers  of  the  piroplasmata  from 
infected  to  healthy  animals,  belong  to  the  class  Arachnoidea 
(spiders,  mites,  etc.).  They  derive  their  nourishment  entirely 
by  sucking  the  blood  of  their  hosts  (terrestrial  vertebrates). 
Ticks  are  very  widely  distributed,  but  they  are  most  numerous 
in  warm  countries.  The  eggs  are  laid  by  the  female  tick  in 
recesses  in  the  ground,  and  after  some  time  six-legged  larvae  are 
hatched  out  and  crawl  upon  the  surrounding  vegetation.  Here 
they  wait  their  opportunity,  until  they  can  attach  themselves  to 
a  warm-blooded  host,  whose  blood  they  suck.  In  some  species  of 
ticks,  the  larvae  having  gorged  on  blood,  drop  off  the  host  on  to 
the  ground,  there  to  undergo  their  metamorphosis  into  eight- 
legged  nymphee,  which  in  turn  attach  themselves  to  a  fresh 
host,  and  again  drop  off  when  gorged,  to  develop  on  the  ground 


544  HYGIENE   AND   PUBLIC   HEALTH 

into  adult  ticks.  In  other  species  the  metamorphosis  from 
larva  to  nymph  may  take  place  upon  the  host;  and  in  other 
species  again  the  whole  cycle  of  changes  from  larva  to  adult  tick 
may  take  place  on  the  host.  It  follows,  then,  that  in  some 
species  only  the  adult  ticks  act  as  carriers  of  the  piroplasma 
parasite,  whilst  in  others  larvae  and  nymphae  as  well  as  adult 
forms  may  play  their  part  in  propagating  piroplasmosis. 

The  Investigation  of  Disease  Outbreaks. 

In  endeavouring  to  arrive  at  the  cause  of  an  outbreak  of  disease 
in  a  community,  it  is  very  seldom  possible  to  obtain  absolute 
and  positive  proof  that  a  certain  circumstance  and  certain 
phenomena  stand  in  the  relation  of  cause  and  effect.  It  is 
generally  only  feasible  to  show  that  there  is  a  greater  probability 
in  favour  of  one  set  of  circumstances  being  the  cause  of  the 
outbreak,  than  of  any  other  set,  because  of  their  more  direct 
relationship  to  the  phenomena  observed. 

In  tracing  the  origin  of  any  outbreak,  all  the  antecedent  facts 
should  be  ascertained  with  regard  to  every  individual  instance 
of  illness,  with  a  view  to  subsequent  comparison  of  the  factors 
respectively  of  agreement  and  disagreement  in  relation  thereto. 
In  addition  similar  inquiries  should  sometimes  be  made  in  respect 
of  persons  hving  under  apparently  identical  conditions  with  those 
who  have  been  attacked  with  illness,  but  who  have  not  them- 
selves fallen  victims,  with  the  object  of  ascertaining  if  there  is  a 
strongly  dividing  line  separating  the  antecedents  of  the  sick  from 
those  of  the  healthy. 

The  method  of  reasoning  employed  is  that  which  is  known  in 
logic  as  the  joint  {inductive)  method  of  agreement  and  difference. 
If  on  inquiry  it  has  been  ascertained  that  a  particular  antecedent 
is  traceable  in  the  history  of  all  cases  that  have  developed  illness, 
whilst  this  particular  antecedent  has  been  as  invariably  absent 
in  the  previous  history  of  the  persons  otherwise  similarly  circum- 
stanced, but  who  have  remained  unaffected,  such  antecedent  is 
the  probable  cause  of  the  illness — the  probability  increasing 
as  the  nurnber  of  incidents  which  conform  with  the  facts 
increase. 

Thus  for  example,  if  in  an  outbreak  of  acute  gastritis  from 
supposed  ptomaine  poisoning,  affecting  a  number  of  people  who 
partook  of  a  common  meal,  it  is  ascertained  that  those  affected 
all  partook  of  a  particular  dish,  whilst  those  unaffected  as  in- 


THE   INVESTIGATION    OF  DISEASE   OUTBREAKS  545 

variably  abstained,  the  presumption  would  be  very  strong  that 
the  implicated  dish  contained  the  poison,  which  was  the  cause  of 
the  illness;  and  the  greater  the  number  of  those  from  whom  this 
evidence  is  obtained,  the  more  likely  is  this  presumption  to  be 
true.  In  outbreaks  of  infectious  illness,  however,  the  essential 
facts  are  always  more  difficult  to  obtain,  and  when  obtainable 
are  not  always  recognized  as  having  any  direct  relation  to  the 
observed  phenomena,  partly  because  the  incubation  period  of 
such  diseases  is  much  longer  than  in  cases  of  acute  irritant 
poisoning,  and  the  incubation  period  itself  is  subject  to  greater 
variation,  and  partly  because  there  is  more  than  one  possible 
cause — often  a  multiplicity — which  have  to  be  borne  in  mind  by 
the  investigator.  This  is  especially  true  of  epidemics  of  enteric 
fever,  where  the  incubation  period  may  vary  from  seven  to 
twenty-one  or  more  days,  and  the  infective  agent  may  be  intro- 
duced into  the  body  by  a  variety  of  channels.  To  separate  out 
in  a  possible  period  of  over  a  fortnight  those  antecedents  in  the 
previous  history  of  an  enteric  fever  patient,  which  are  of  direct 
concern,  from  irrelevant  details  which  can  have  no  bearing 
upon  the  point  at  issue,  is  a  work  which  can  only  be  adequately 
performed  by  a  mind  trained  to  elucidate  such  phenomena,  and 
well  stored  with  the  knowledge  which'alone  can  serve  to  separate 
efficiently  the  wheat  from  the  chaff. 

In  such  investigations  conclusions  are  often  arrived  at  which 
carry  little  conviction  to  the  minds  of  critical  observers;  and 
this  frequently  happens  from  the  adoption  alone  of  the  inductive 
method  of  agreement,  the  method  of  difference  being  too  often 
discarded.  It  cannot  be  too  much  insisted  upon  that  the  collec- 
tion of  certain  data  showing  that  all  the  cases  of  illness  have  had 
a  common  antecedent — such  for  instance  as  the  consumption  of 
a  certain  water  or  food  within  the  supposed  period  of  incubation 
— is  no  proof  that  such  antecedent  is  the  cause,  in  the  absence  of 
further  proof  that,  in  respect  of  others  hving  under  similar 
conditions,  but  who  are  unaffected,  their  previous  history  is 
unassociated  with  the  particular  antecedent  circumstance,  which 
is  so  invariably  present  in  the  history  of  those  affected. 

In  many  instances  it  must  happen  that  the  antecedent 
suspected  of  being  the  cause  is  only  found  in  a  majority  of  the 
instances  where  illness  has  ensued — not  in  all;  and  is  even  present 
in  some  few  instances,  where  illness  has  not  ensued.  These 
exceptions  are  often  capable  of  explanation,  and  do  not  neces- 

35 


546  HYGIENE    AND   PUBLIC    HEALTH 

sarily  invalidate  the  whole  argument,  where  the  origin  of  infec- 
tious disease  is  concerned. 

A  good  rule  for  the  investigator  to  bear  in  mind  is  to  be  very 
careful  to  exclude  all  the  more  commonly  recognized  causes, 
before  he  ventures  to  assign  as  a  cause  some  circumstance  of  an 
unusual  character  in  that  connection,  which  appears  to  him  to 
fit  in  with  the  facts.  Sometimes  the  facts  appear  capable  of 
explanation  on  two  hypotheses,  one  more  or  less  familiar,  and 
easily  intelligible,  the  other  more  novel  and  puzzling.  The  first 
should  be  excluded  as  far  as  exclusion  is  possible,  before  the 
second  is  adopted. 

Sometimes  the  experimental  method  is  available  as  an  aid  to 
the  arrival  at  a  sound  conclusion  of  the  cause  of  an  outbreak  or 
epidemic;  and  it  occasionally  happens  that  what  are  to  all  intents 
and  purposes  unconscious  "  experiments,"  occur  to  verify  hypo- 
theses previously  unsubstantiated.  For  instance,  an  outbreak 
of  diphtheria  in  a  school  is  attributed  to  the  presence  of  a  boy 
with  a  chronic  nasal  ulceration  and  discharge.  The  boy  is  sent 
to  his  home,  and  the  outbreak  terminates.  On  his  return  to 
school  some  weeks  later,  other  boys  who  have  relation  of  some 
sort  with  him,  develop  diphtheria,  and  bacterioscopic  examina- 
tion shows  that  the  Klebs-Loeffler  bacillus  is  present  in  the  nasal 
secretion  of  this  boy,  who  has  been  the  unwitting  carrier  of 
infection.  Again,  experiment  on  a  large  scale  has  demonstrated 
that  rats  carry  the  infection  of  plague,  and  are  a  means  of  con- 
veying it  to  man ;  and  the  part  played  by  mosquitoes  (Anopheles) 
in  the  propagation  of  malaria  has  been  strikingly  confirmed  by 
experiment  on  the  human  subject;  and  the  same  is  true  of  yellow 
fever. 

In  conclusion  it  may  be  said  that  in  any  investigation  of  a 
disease  outbreak,  the  really  important  matter  is  the  due  appre- 
ciation and  collection  of  all  the  facts  which  have  a  bearing  on 
the  subject,'^and  their  marshalHng  in  a  systematic  and  intelligent 
manner.  It  may  be  possible  on  these  foundations  to  hypothesize 
a  cause  for  the  outbreak;  but  should  this  be  unascertainable  on 
the  facts  reported,  there  is  no  reason  to  deplore  a  failure,  which 
in  the  light  of  future  knowledge  may  be  capable  of  explanation. 
It  is  far  better  to  record  the  facts  irrespective  of  any  theory 
as  to  their  origin,  than  to  endeavour  to  make  the  facts  fit  the 
theory. 


the   isolation  of  the    infectious  sick  547 

The  Isolation  of  the  Infectious  Sick. 

This  can  only  be  attained  by  a  system  of  compulsory  notification 
of  all  infectious  diseases  to  the  sanitary  authority  of  the  district. 
It  will  then  generally  be  possible  to  isolate  the  first  case  or  cases 
of  the  disease  as  they  occur,  to  destroy  the  infection  already 
generated,  and  to  control  the  movements  of  the  individuals  with 
whom  the  sick  person  may  have  come  into  contact.  Without 
compulsory  notification  it  must  almost  necessarily  happen  that 
the  disease  obtains  headway  before  it  is  recognized,  and  then 
the  most  persevering  efforts  too  often  fail  to  obtain  such  a  control 
as  will  prevent  its  widespread  dissemination. 

There  are  many  who  are  in  favour  of  a  greater  extension  of 
the  range  of  notifiable  diseases,  and  would  advocate  the  notifica- 
tion of  influenza,  cerebro-spinal  fever,  dysentery,  ague,  remittent 
fever,  glanders,  syphilis,  septicaemia,  purpura,  tuberculosis,  pneu- 
monia and  acute  rheumatism.  As  preventive  measures  are  not 
limited  to  the  control  of  infective  diseases,  good  results  might 
follow,  and  much  valuable  knowledge  would  accrue  by  the 
adoption  of  some  system  of  compulsory  notification  of  certain 
non-infectious  illnesses. 

The  isolation  of  all  cases  of  contagious  disease  must  be  regarded 
as  a  most  desirable  measure,  but  is  absolutely  indispensable  in 
the  case  of  the  epidemic  diseases  with  air-borne  contagia,  if  it  is 
hoped  to  limit  their  spread.  Tubercular  diseases  are  rarely 
isolated,  but  it  is  probable  that  such  a  measure  applied  to 
tuberculosis  with  discharges  would  have  a  considerable  effect  in 
limiting  their  spread.  The  more  usually  inoculable  diseases — 
with  the^'exceptions  of  leprosy,  where  segregation  of  the  sick 
should  be  rigidly  enforced,  and  of  contagious  ophthalmia— do 
not  seem  to  demand  measures  of  isolation. 

A  difficulty  arises  in  the  case  of  measles  that  the  pre-eruptive 
stage  is  infectious,  and  that  before  the  isolation  can  be  effected 
other  susceptible  persons  have  probably  caught  the  infection. 
In  measles  and  whooping  cough  also,  the  contagion  is  so  diffusible 
and  universal  that  few  can  hope  to  escape ;  and  the  tender  age 
of  the  sufferers  in  these  and  other  infantile  complaints  renders 
them  less  suitable  for  hospital  treatment  than  is  the  case  with 
older  children  and  adults. 

Where  removal  to  hospital  is  not  feasible,  isolation  must  be 
attempted  by  placing  the  patient  in  a  room  by  himself  at  the 


548  HYGIENE    AND    PUBLIC   HEALTH 

top  of  the  house,  all  communication  with  the  other  inmates  being 
forbidden ;  and  the  aerial  connection  between  the  sick-room  and 
the  rest  of  the  house  must  be  broken  as  much  as  possible  by 
hanging  up  outside  the  door  a  sheet  kept  constantly  soaked  with 
some  disinfectant  liquid.  Nothing  must  be  allowed  to  pass  out 
of  the  sick-room  unless  previously  disinfected,  and  all  dressings, 
poultices,  and  rags  should  be  immediately  burnt  after  use. 

Hospitals. 

The  aggregation  of  a  large  number  of  sick  persons  suffering 
from  a  variety  of  diseases  or  recovering  from  surgical  operations, 
in  one  common  building  is  a  necessity  of  modern  life,  but  is  now 
recognized  as  being  often  attended  with  risks  and  dangers  from 
which  the  patient  treated  in  his  own  house  is  to  a  large  extent 
exempt.  In  former  times  this  crowding  together  of  the  sick 
in  hospitals  led  to  outbreaks  of  erysipelas,  pyaemia,  and  hospital 
gangrene  in  the  surgical  wards,  the  contagion  appearing  to  be 
conveyed  from  one  patient  to  another  through  the  air,  or  by 
means  of  the  hands  or  instruments  of  the  surgeon  or  nurse.  The 
aseptic  treatment  of  wounds  and  injuries,  and  the  greater  care 
bestowed  on  the  construction  and  management  of  hospitals,  have 
nearly  eradicated  these  terrible  diseases  from  modern  hospital 
practice;  but  when  from  any  cause  the  surgical  wards  of  hospitals 
are  overcrowded,  and  the  cleanliness  and  frequent  dressings  of 
wounds  cannot  be  attended  to,  these  septic  diseases  are  almost 
sure  to  make  their  appearance. 

It  has  often  been  noticed  that  cases  of  open  wounds  from 
injury  or  operation  recover  far  more  rapidly  when  treated  in  the 
open  air,  or  in  huts  and  tents  practically  open  to  the  air,  than 
when  confined  in  close  buildings;  and  the  same  is  true  of  most 
acute  infectious  diseases.  For  such  the  breathing  of  pure  air  is  a 
piophylactic  worth  more  than  all  the  drugs  in  the  Pharmacopoeia. 

The  first  principle,  then,  in  hospital  construction  and  manage- 
ment is  bound  up  in  an  abundant  supply  of  pure  air  to  the 
patients.  The  putrescent  organic  effluvia  from  the  skins  and 
lungs  of  sick  persons,  which,  if  not  more  copious,  are  certainly 
more  deleterious  than  those  from  healthy  people,  must  be 
diluted  with  fresh  air  and  rapidly  carried  away.  For  each 
patient  in  a  medical  ward  the  superficial  floor  space  should  not 
be  less  than  loo  square  feet,  and  the  cubic  space  i,ooo  cubic 
feet.     The  air  should  be  changed  at  least  three  times  in  an  hour.. 


HOSPITALS  549 

which  would  give  3,000  cubic  feet  of  fresh  air  per  head  per  hour. 
In  wards  containing  patients  suffering  from  phthisis,  a  higher 
set  of  figures  should  be  taken. 

For  infectious  disease  hospitals  the  minimum  floor  space 
should  be  144  square  feet,  and  the  minimum  cubic  space  2,000 
cubic  feet  per  head,  changed  three  or  four  times  an  hour.  Each 
bed  should  have  at  least  12  linear  feet  of  wall  space.  The  window 
surface  should  be  in  the  proportion  of  i  square  foot  to  about 
every  70  feet  of  cubic  space,  in  order  that  the  wards  shall  be  well 
lighted.  At  night  time  the  wards  are  best  lighted  by  electric 
light,  and  failing  that  by  incandescent  gas  burners. 

For  general  hospitals  it  is  found  that  the  most  convenient 
number  of  patients  that  may  be  treated  in  one  ward  is  on  an 
average  thirty,  this  being  the  number  which  one  nurse  can 
readily  supervise.  In  an  oblong  ward  with  thirty  patients,  each 
patient  to  have  100  square  feet  of  floor  space  and  1,000  cubic 
feet  of  air  space,  3,000  square  feet  of  floor  space  will  be  required 
and  30,000  cubic  feet  of  air  space.  The  3,000  square  feet  of 
floor  space  will  be  available  if  the  ward  is  120  feet  long  and  25 
feet  wide.  As  there  are  fifteen  beds  on  each  side  of  the  ward,  the 
longitudinal  wall  space  for  each  bed  will  be  8  feet,  and  the 
distance  between  any  two  beds  (themselves  3  feet  wide  and 
6^  feet  long)  will  be  5  feet.  The  width  of  25  feet  is  a  convenient 
one,  as  it  allows  a  passage  11  feet  wide  between  the  two  rows  of 
beds  for  the  whole  length  of  the  ward,  and  permits  of  thorough 
cross  ventilation  between  the  opposite  windows,  and  the  flooding 
of  every  part  of  the  ward  with  daylight. 

To  provide  the  30,000  cubic  feet  of  air  space  the  ward  must  be 
10  feet  high.  It  would  be  better  to  have  the  height  of  the  ward 
12  feet,  which  would  allow  1,200  cubic  feet  of  air  space  per 
patient.  Any  height  above  13  or  14  feet  is  useless  for  purposes  of 
ventilation,  and  should  be  discounted  in  calculating  the  cubic 
space  per  head. 

There  is  a  growing  disposition  to  provide  small  wards  in  fever 
hospitals,  as  such  wards  appear  to  be  more  favourable  to  the 
patient's  recovery  and  to  reduce  the  risk  of  secondary  infections. 
They  facilitate,  moreover,  some  classification  of  the  patients 
according  to  the  severity  of  the  attack  and  the  stage  in  the 
disease  at  which  they  have  arrived.  It  is  desirable  to  provide 
a  little  extra  space  in  the  female  wards,  as  children  of  both  sexes 
may  be  nursed  in  them. 


550  HYGIENE    AND    PUBLIC    HEALTH 

Provision  should  be  made  for  the  entrance  of  warmed  fresh 
air  to  the  wards  in  winter;  this  may  be  effected  by  Galton's 
ventilating  open  fire-place,  or  by  a  ventilating  stove  or  stoves 
placed  in  the  centre  of  the  ward.  Shorland's  Manchester  grates 
are  much  used.  For  warming  purposes,  hot-water  pipes  should 
also  be  placed  in  the  ward,  as  they  may  be  required  during  very 
cold  weather.  They  should  be  placed  in  a  position  convenient 
of  access  for  cleansing  any  space  behind  or  below  them,  and 
should  not  be  fixed  in  channels  or  chased  recesses  in  walls  or 
floors.  Radiators  heated  by  hot  water  are  now  more  commonl}' 
used  than  "  hot-water  pipes." 

To  secure  the  best  kinds  of  natural  ventilation,  the  ward  should 
have  opposite  windows  reaching  nearly  to  the  ceihng,  and  the 
upper  portion  of  each  window  should  be  provided  with  side  flaps 
and  made  to  revolve  on  its  lower  border  into  the  ward,  so  as  to 
admit  fresh  air  during  warm  weather  in  an  upward,  slanting 
direction.  Hinckes-Bird's  arrangement  may  also  be  applied 
to  the  windows.  It  is  sometimes  desirable  to  have  an  inlet  for 
fresh  air,  which  can  be  warmed  in  winter,  close  to  the  floor  at 
the  head  of  each  bed,  in  order  to  ventilate  the  space  under  the 
bed,  and  at  once  carry  away  the  respired  air  and  effluvia  from 
each  patient.  The  inlet  is  now  generally  arranged  in  connection 
with  the  hot-water  radiator.  For  the  escape  of  the  heated  and 
vitiated  air,  extraction  shafts  may  be  provided,  opening  near  the 
c filing,  which  should  be  joined  together,  the  single  shaft  so 
formed  being  then  carried  up  in  close  contact  with  the  stove  or 
chimney  flue,  in  order  that  the  column  of  air  in  it  may  not  be 
allowed  to  cool  and  hinder  the  up  draught.  In  summer,  when 
the  stoves  are  not  in  action,  the  same  result  may  be  produced  by 
burning  gas  in  Bunsen  burners  at  the  bottom  of  the  extraction 
shafts,  or  by  means  of  a  revolving  fan  at  the  top  of  the  shaft. 

Recent  experience,  however,  shows  that  extraction  shafts 
imless  easily  accessible  throughout  their  entire  length  for  cleans- 
ing, are  undesirable,  and  it  is  preferable  to  rely  upon  window 
openings  and  chimney  flues  for  the  escape  of  vitiated  air. 

In  the  ventilation  of  hospital  wards,  the  "  propulsion  "  or 
"  plenum  "  method  is  regarded  with  favour,  because  when  air 
is  propelled  into  a  building  the  source  of  supply  can  be  chosen, 
and  the  air  can  be  cleansed,  warmed,  and  brought  to  a  suitable 
hygrometric  condition.  The  chance  of  infection  being  carried 
aerially  from  ward  to  ward  is  lessened,  from  the  circumstance 


HOSPITALS  551 

that  the  air  supply  to  each  ward  can  be  kept  quite  distinct  and 
separate.  There  is,  however,  one  condition  essential  to  the 
success  of  the  "  plenum  "  system  of  ventilation,  which  is 
generally  regarded  with  disfavour,  viz.,  that  the  movement  of  air 
must  be  kept  absolutely  under  control,  and  consequently  that 
the  opening  of  windows  cannot  be  permitted;  moreover,  the 
maintenance  of  the  air  at  the  same  uniform  temperature, 
humidity,  and  rate  of  movement,  tends  to  have  an  enervating 
and  depressing  effect  upon  patients  and  nurses.  For  this  reason 
the  system  is  not  now  regarded  with  favour  for  hospital  purposes. 
The  General  Hospital  at  Birmingham  is  ventilated  on  the 
plenum  system.  In  this  building  the  main  air  ducts  are  carried 
under  the  corridors,  from  which  separate  flues  are  carried  up  to 
the  several  wards,  the  air  outlets  being  at  the  floor  level.  The 
vitiated  air  is  carried  away  through  ventilating  turrets  at  the 
ends  of  the  wards.  Where  an  extraction  system  alone  is  relied 
upon,  the  entering  air  is  incapable  of  regulation,  both  as  to  its 
source  and  its  amount. 

The  water-closets,  bath-rooms  and  slop-sinks  should  be  placed 
in  a  block  outside  the  ward,  but  connected  with  it  by  a  cross 
ventilated  lobby.  By  this  means,  if  disconnection  of  waste 
pipes  and  ventilation  of  soil  pipes  are  properly  attended  to,  there 
is  no  risk  of  foul  drain  air  gaining  access  to  the  ward.  Proper 
hospital  slop-sinks  are  necessary  for  washing  and  emptying 
bed-pans,  spittoons,  and  urine  slippers.  They  should  be  made 
of  porcelain,  enamelled  fireclay,  or  aluminium,  should  be  of 
large  size,  at  least  15  inches  square  at  the  top,  with  upward 
sluice  or  jet  for  cleansing  the  bed-pans,  and  should  be  flushed 
from  a  water-waste  preventer. 

Almost  as  important  as  good  ventilation  is  the  provision  of 
internal  surfaces  (walls,  floors,  and  ceilings)  to  the  wards,  which 
will  not  hold  or  absorb  organic  effluvia.  The  occurrence  of 
erysipelas  and  surgical  fever  in  the  past  has  been  favoured  by 
wooden  floors  with  chinks  and  crevices  between  the  boards. 
The  organic  matters  from  poultices  and  dressings  find  their  way 
into  these  crevices,  and  accumulate  under  the  flooring. 

The  floors  of  the  wards  should  be  covered  with  oak  parqueterici 
or  with  solid  wood  block  flooring  without  chinks  or  cracks,  laid 
on  a  bed  of  concrete.  Narrow,  well-seasoned  deal  boards, 
tongued  and  grooved,  are  less  satisfactory,  but  far  cheaper. 
The  surface  should  be  painted,  or  stained  and  varnished,  and 


552 


HYGIENE    AND    PUBLIC   HEALTH 


kept  clean  without  washing.  The  parqueted  floors  should  be 
oiled  and  beeswaxed;  or  melted  paraffin  may  be  ironed  into  the 
woodwork,  which  it  penetrates  for  about  J  inch,  forming  an 
unbroken  surface  which  remains  good  for  years. 


I'lc.  85. — Hospital   Sloi'-Sink  with  Flushing  Rim  and  Bed-Pan  and 
Slipper  Douches. 


Other  materials  for  hospital  floors  are  teak  and  maple 
boards  (tongued  and  grooved),  linoleum  laid  direct  on  the  coke 
breeze  cement  of  the  fire-proof  floor,  terrazo  (marble  chips  set 


HOSPITALS  553 

in  cement),  and  various  patented  materials  like  "  doloment," 
"  stonwod,"  and  "  eubaeolith,"  which  are  formed  of  compressed 
sawdust,  shavings,  and  cement.  Terrazo  is  rather  cold  and 
slippery,  and  the  patented  floors  are  liable  to  crack.  Linoleum 
is  found  to  answer  well,  as  it  is  warm,  elastic,  and  non-slippery. 
It  should  not  be  laid  over  a  boarded  floor. 

It  is  most  essential  to  avoid  washing  floors  with  water.  The 
air  of  the  wards  is  by  this  means  chilled  from  evaporation  when 
the  floor  is  drying.  All  cornices,  corners,  and  ledges  should  be 
avoided  in  the  wards,  and  angles  rounded  of^,  so  as  to  offer  every 
facility  for  cleansing. 

The  wall  surfaces  should  be  impermeable.  Glazed  brickwork 
or  glazed  tiles  set  in  Portland  cement  afford,  perhaps,  the  best 
and  most  easily  cleaned  surface,  but  they  are  apt  to  condense 
moisture  on  their  surfaces.  The  walls  may  also  be  coated  with 
Keen's  cement  or  Robinson's  fire-proof  cement,  painted,  or  even 
distempered,  if  tiles  are  too  costly.  Ceilings  may  be  cemented 
and  painted,  or  limewashed. 

The  bedsteads  should  be  of  iron,  with  spring  wire  mattresses, 
and,  in  the  surgical  wards,  provided  with  movable  fracture 
boards.  It  is  very  important  to  reduce  the  furniture  of  the  ward 
to  a  minimum,  and  to  allow  no  curtains,  hangings,  or  drapery  of 
any  sort. 

Excreta,  sputa,  dirty  dressings,  and  poultices  must  be  removed 
from  the  wards  at  very  frequent  intervals.  In  the  case  of  in- 
fectious disease  hospitals,  it  is  very  desirable  that  the  solid  refuse 
matters  should  be  burned.  This  can  be  done  by  means  of  a  small 
destructor  furnace  in  connection  with  the  boiler-house  or  heating 
furnace  of  a  large' hospital. 

No  harm  has  been  shown  to  result  from  allowing  the  drains 
from  a  fever  hospital  to  empty  into  the  public  sewer,  or  from  the 
slop  waters  being  disposed  of  by  sub-irrigation. 

For  the  exercise  of  the  patients,  covered  balconies  on  the 
southern  or  western  aspect  of  the  building  should  be  provided; 
and  in  large  towns,  where  space  for  a  garden  is  wanting,  a  flat 
roof  affords  a  valuable  exercise  and  recreation  ground. 

In  some  of  the  more  recently  constructed  hospitals,  it  has  been 
found  convenient  to  place  the  kitchens  and  sculleries  at  the  top 
of  the  building,  and  to  use  gas  and  steam  for  all  culinary  purposes. 
Every  town  should  have  hospital  accommodation  for  the  isola- 
tion of  cases  of  infectious  disease.     The  amount  of  accommo- 


554  HYGIENE  AND  PUBLIC  HEALTH 

dation  required  will  depend  upon  the  character  of  the  population 
and  the  rate  of  its  increase,  the  housing  and  the  habits  of  the 
people,  and  the  amount  of  intercourse  with  other  places  from 
which  infectious  disease  may  be  introduced;  but  it  may  be  stated 
generally  that  there  should  be  at  least  one  bed  to  every  i,ooo 
of  the  population,  when  this  is  largely  composed  of  the  industrial 
classes.  A  site  should  be  chosen  outside  the  town,  in  a  thinly 
populated  neighbourhood,  with  a  southern  exposure,  a  dry 
subsoil,  a  good  fall  for  drainage,  and  easy  of  access  from  the 
town.  Separate  pavilions  should  be  set  aside  for  the  separate 
accommodation  of  each  different  disease  to  be  treated.  The  best 
arrangement  is  to  place  the  pavihons  on  a  north  and  south  line, 
with  easterly  and  westerly  aspects,  so  that  every  side  can  receive 
sunshine. 

Where  space  will  admit,  the  system  of  one-storied  pavilions 
is  far  the  best  for  all  hospitals,  and  is  especially  suited  for  those 
intended  for  infectious  diseases.  The  pavilions  are  connected 
with  one  another  and  with  the  administrative  blocks  by  corridors 
which  are,  or  may  be,  open  to  the  air;  and  all  risk  of  transference 
of  foul  air  and  effluvia  from  one  ward  to  another  is  thus  avoided. 
In  large  towns  a  certain  amount  of  crowding  on  a  limited  area 
is  unavoidable,  and  wards  of  two  or  more  stories  in  height  must 
be  built.  Even  in  these  the  system  of  disconnected  pavilions 
should  be  aimed  at,  and  the  staircases  require  careful  planning 
to  prevent  them  acting  as  shafts  for  the  passage  of  air  from  one 
ward  to  another.  The  external  air  space  around  the  wards 
should  be  ample,  and  overshadowing  by  high  buildings  in  the 
neighbourhood  must  be  carefully  avoided. 

Hospitals  constructed  of  semi-permanent  material  have  been 
found  successful  in  the  British  Army,  and  the  same  principle  is 
now  being  applied  in  civil  hospitals.  The  weight  of  the  structure 
is  taken  by  steel  uprights  and  girders  resting  on  concrete  founda- 
tions, whilst  the  wall  spaces  between  the  steel  supports  are  filled 
with  hollow  bricks  of  earthenware  or  terra-cotta.  The  air  cavity 
acts  as  a  non-conductor,  and  prevents  loss  of  heat.  Such  build- 
ings are  much  cheaper  to  erect  than  permanent  brick  structures, 
and  are  likely  to  prove  much  more  lasting  than  galvanized  iron 
and  wooden  buildings.  The  wards  should  be  warmed  by  hot- 
water  radiators,  as  well  as  by  open  fireplaces,  especially  where  the 
building  is  in  an  exposed  position.  Similar  buildings  have  been 
constructed  of  steel  framework  with  double  uralite  slabs,  so  as 


HOSPITALS 


555 


556  HYGIENE   AND   PUBLIC   HEALTH 

to  form  a  hollow  wall.  If  such  buildings  are  erected  of  more 
than  one  story,  the  floor  should  be  of  fire-proof  construction 
(coke-breeze  cement  resting  on  steel  girders). 

In  epidemic  periods  it  may  be  necessary  to  supplement  existing 
hospital  accommodation,  and  for  this  purpose  tents  (in  summer) 
or  huts  of  galvanized  iron,  wood,  Willesden  waterproof  material, 
or  Doecker's  material  (a  waterproof  composition  resembling 
leather),  can  be  erected.  Huts  of  the  last  three  materials  are 
preferable  to  iron,  as  they  are  easier  to  warm.  The  floors  should 
be  raised  a  foot  from  the  ground,  and  the  ridge  of  the  roof  should 
be  used  for  ventilation  as  well  as  the  windows.  If  these  huts  are 
constructed  with  hollow  walls,  the  temperature  in  cold  weather 
can  be  properly  maintained  with  efficient  ventilation — a  difficult 
task  without  hollow  walls,  owing  to  the  thinness  of  the  materials. 
As  the  wood  and  waterproof  compositions  used  in  the  construc- 
tion of  these  hut  hospitals  are  hable  to  rot  and  decay,  they  can 
only  be  regarded  as  temporary  structures,  and  as  soon  as  the 
emergency  which  necessitated  their  erection  is  over,  they  are 
best  pulled  down  and  destroyed. 

As  the  late  Sir  Richard  Thome  pointed  out,  the  provision  for 
isolating  infectious  cases  is  best  carried  out  with  deliberation  in 
non-epidemic  periods.  Extemporized  hospitals,  erected  to  meet 
the  demands  of  a  sudden  outbreak,  are  often  not  ready  for  occupa- 
tion until  the  immediate  cause  for  their  erection  has  passed  by, 
and  they  provide  accommodation  of  a  very  indifferent  sort.  A 
memorandum  of  the  Local  Government  Board  states  that  in  a 
village  a  small  cottage,  capable  of  isolating  four  cases  in  two 
separate  rooms,  should  at  least  be  provided;  but  a  minimum  in 
other  cases  should  be  four  small  permanent  wards  of  brick,  stone, 
or  concrete, this  accommodation  being  capable  of  being  extended, 
if  need  be,  by  tents,  or  huts.  As  some  future  extension  is  almost 
inevitable  the  administrative  block  should  be  built  in  excess 
of  the  requirements  at  the  time  of  construction.  It  is  never 
desirable  to  accommodate  more  than  twenty  persons  per  acre, 
and  the  hospital  buildings  should  always  be  40  feet  from  the 
boundary  fence,  which  should  be  at  least  6  feet  6  inches  in  height. 
Temporary  (wood  and  iron)  hospitals  are  not  approved  of  by 
the  Local  Government  Board;  for  if  these  are  constructed  so 
as  to  ensure  a  fairly  equable  ward  temperature,  the  cost  is  about 
the  same  as  that  incurred  in  the  erection  of  ordinary  brick 
buildings,  while  they  are  less  durable  and  more  expensive  to  keep 


HOSPITALS  557 

in  repair.  Moreover,  wooden  lined  wards  are  not  adapted  to 
the  varying  needs  of  a  permanent  building,  and  the  risks  from 
fire  are  very  great  in  such  wooden  structures. 

Certain  general  regulations  must  be  observed  in  all  fever  hos- 
pitals. No  member  of  the  sta.fi  must  leave  the  premises  without 
first  changing  the  outer  garments;  tradesmen  must  never  be 
permitted  to  pass  beyond  the  boundary  wall  or  fence;  the  visits 
to  the  patients  should  be  limited  to  the  nearest  relatives  and  the 
most  intimate  friends  of  those  patients  who  are  dangerously  ill, 
and  then  one  visit  only  of  fifteen  minutes"  duration  should  be 
sanctioned  each  day;  all  visitors  should  be  made  to  wear  overalls 
on  entering  the  ward,  and  to  wash  their  hands  and  faces  on  leaving 
it;  they  should  also  be  warned  against  entering  any  public 
conveyance  immediately  after  quitting  the  ward. 

Hospital  buildings  will  include  ward  blocks,  an  administrative 
block  for  the  housing  of  the  staff  and  stores,  and  out-offices,  such 
as  laundry,  mortuary,  and  disinfecting  station.  The  administra- 
tive block  should  be  placed  so  as  to  control  the  entrance  to  the 
hospital  grounds  in  the  absence  of  a  porter's  lodge,  and  it  should 
be  built  on  a  scale  somewhat  in  excess  of  what  may  be  first  re- 
quired, so  that  it  will  be  sufficient  for  future  extensions  of  the 
hospital.  The  drains  from  each  ward  block  should  be  trapped 
from  the  common  drain,  and  separately  ventilated. 


CHAPTER  X 
SCHOOL  HYGIENE 

I.  Notes  upon  the  School  Premises. 

In  selecting  the  site  for  a  school,  regard  should  be  paid  to  a 
central  position  and  the  facilities  of  access  by  the  scholars.  A 
noisy  site  is  very  undesirable,  and,  if  a  quiet  site  cannot  be  ob- 
tained, the  building  should  be  set  back  at  least  60  feet  from  the 
street. 

In  planning  a  school  building  the  schoolrooms  must  be  the 
prime  consideration ;  the  building  should  be  a  number  of  school- 


FlG. 


-Diagrammatic  Rj;pRKsiiNTATioN  of  E-shaped  School. 


rooms  properly  disposed,  and  not  a  whole  cut  up  into  school- 
rooms, whose  size  and  arrangement  are  dependent  upon  the 
size  and  shape  of  the  building  (E.  R.  Shaw).  If  possible,  the 
rule  should  be  observed  that  lines  drawn  from  the  bottom  of 
the  walls  of  the  building  to  the  tops  of  the  nearest  adjacent 
buildings  should  not  make  a  greater  angle  that  30°  with  the 
horizon.  It  is  desirable  that  the  building  should  never  exceed 
two  stories  in  height,  and  the  main  corridors  or  halls  should  be 

558 


SCHOOL   HYGIENE 


559 


at  least  lo  feet  in  width  and  well  lighted.  A  corridor  or  pavilion 
plan  of  buildings  is  preferable  to  the  type  in  which  the  class- 
rooms are  grouped  around  a  central  hall,  for  the  reasons  that  in 
the  former  case  the  ventilation,  by  natural  means,  is  much  more 


SECTION. 


Fig.  89. — ^The  Staffordshire  Type  of  Elementary  School.  Ground 
Plan  of  Infants'  School,  with  Drill  and  Play  Hall.  Also 
Section  of  Classroom. 

efficient,  and  the  occasional  distractions  in  the  classrooms,  from 
the  use  of  the  hall,  are  avoided. 

The  satisfactory  lighting  of  school  classrooms  demands  an 
aspect,  etc.,  which  will  ensure  sufficient  hght  in  every  part  of 


560  HYGIENE  AND  PUBLIC  HEALTH 

such  room,  even  on  dull  daj^s.  Whereas  the  predominant  light 
should  fall  on  the  scholar's  left,  it  is  not  desirable  that  all  the 
light  should  do  so,  or  the  scholars  may  cast  shadows  on  the  desks 
of  those  working  immediately  on  their  right.  It  is  important 
that  there  should  be  no  glare  from  the  light;  with  the  object  of 
avoiding  this,  the  windows  should  be  fitted  with  outside  linen 
shades  to  cut  off  sunshine,  and  in  the  case  of  artificial  light  the 
globes  should  be  glazed  and  capable  of  absorbing  excess  of  ultra- 
violet rays.  Occasionally  ordinary  window  illumination  has  to 
be  supplemented  by  prism  panes  and  reflectors,  the  latter  being 
placed  at  an  angle  of  35°.  For  artificial  illumination  either 
electric  inverted  lamps  or  incandescent  inverted  gas-burners 
should  be  employed.  These  lights  should  be  placed  at  a  height 
of  about  6  feet  from  the  floor  and  at  intervals  of  about  6  feet 
apart,  measuring  from  the  first  light,  which  should  be  placed  a 
little  to  the  left  of  the  first  seat  in  the  first  row  facing  the  teacher. 
A  sufficiently  good  test  of  illumination  would  be  the  power  of  an 
individual  with  average  vision  to  read  small  pica,  with  ease  and 
comfort,  at  a  distance  of  12  inches  from  the  eyes.  The  generally 
accepted  standard  for  artificial  illumination  is  at  least  10  to 
15  candle  metres  on  desks,  and  this  would  not  represent  more 
than  one-third  of  the  usual  dayhght  standard.  (A  candle  metre 
represents  the  light  from  a  standard  sperm  candle  at  a  distance 
of  I  metre.) 

The  area  of  the  windows,  clear  of  sash'^frames,  should  be  from 
one-fourth  to  one-sixth  of  the  floor  space  of  the  room.  The 
windows  should  reach  as  high  as  the  ceiling  of  the  room,  and 
open  directly  into  the  external  air,  and  the  intervals  between 
them  should  be  as  small  as  possible.  The  height  of  the  sills 
from  the  floor  should  never  be  less  than  4  feet.  The  defective 
lighting  in  schoolrooms  is  one  of  the  chief  causes  of  short-sight; 
the  child,  not  being  able  to  read  its  book  when  placed  at  the 
proper  distance  (at  least  12  inches)  from  its  face,  stoops  over  the 
desk  to  lessen  the  distance ;  the  eyes  converge  when  brought  too 
near  the  object,  and  the  muscular  strain  thus  induced  leads  to  a 
yielding  of  the  plastic  eyeball,  with  an  elongation  of  its  antero- 
posterior axis,  and  myopia  results;  i.e.,  the  image  of  the  object 
seen  forms  in  front  of  the  retina  (unless  the  object  itself  is  very 
close  to  the  eyes),  and  is  blurred  and  indistinct.  Imperfect 
lighting  also  leads  to  the  use  of  artificial  light,  which  often 
adds  to  the  vitiation  of  the  atmosphere. 


SCHOOL   HYGIENE  561 

Suitable  arrangements  for  the  warming  of  school  classrooms 
must  be  provided  to  maintain  a  temperature  of  65°  F.  in  the 
infant  department,  and  one  from  56°  to  60°  F.  in  classrooms 
for  the  older  children;  this  must  be  done  while  considerable 
quantities  of  fresh  air  are  being  admitted,  and  never  at  the 
expense  of  fresh  air.  It  may  be  taken  for  granted  that  if  rooms 
are  not  properly  warmed  they  will  not  in  practice  be  properly 
ventilated.  For  warming  purposes,  the  best  method  is  the  low- 
pressure  hot-water  system,  with  sufficient  radiators  and  pipes. 
Roughly,  from  12  to  16  feet  of  low-pressure  piping  is  necessary 
for  every  1,000  cubic  feet,  in  classrooms;  and  18  feet  should  be 
provided  in  infant  departments  and  in  rooms  at  the  end  of  a 
circuit.  The  ventilating  fire-grates  constitute  the  next  best 
method  of  warming  in  small  classrooms;  two  smaller  grates 
should  be  provided  rather  than  one,  wherever  this  is  practicable. 
A  good  expedient  is  to  provide  a  fireplace  that  has  a  boiler 
immediately  behind  it  which  suppUes  hot  water  to  a  system  of 
pipes  leading  from  it  around  the  classroom,  through  radiators^ 
and  back  again  to  the  boiler.  Slow  combustion  stoves  take  up 
valuable  space,  and  are  less  satisfactory.  The  walls  and  furni- 
ture of  classrooms  should  always  be  warmed  to  about  60°  F. 
before  the  children  enter. 

Every  classroom  should  have  a  thermometer,  placed  away 
from  the  fire,  and  at  breathing  level.  Except  in  very  small  class- 
rooms, fires  must  be  supplemented  by  some  other  heating  agency. 
Hot-water  pipes  should  always  be  made  to  assist  ventilation. 
Stoves  are  not  desirable,  but,  when  introduced,  they  should  be 
ventilating  stoves  and  provided  with  chimneys.  The  warming 
of  corridors  and  lobbies  is  of  great  importance. 

Some  system  of  artificial  ventilation,  with  a  supply  of  warmed 
fresh  air,  is  necessary  for  schoolrooms  where  the  amount  of  cubic 
space  per  head  is  very  Hmited.  The  English  Education  Depart- 
ment requirements  are  only  100  cubic  feet  of  space  per  scholar 
and  10  square  feet  of  floor  space.  These  are  the  minimum 
requirements;  but  even  with  double  these  amounts,  adequate 
ventilation  by  natural  means  in  cold  weather  would  be  produc- 
tive of  draught  and  a  great  lowering  of  temperature  in  the  room. 
Dr.  Newsholme  is  of  opinion  that  good  average  requirements  for 
schools  are,  for  each  scholar,  150  cubic  feet  of  space,  15  square 
feet  of  floor  space,  and  1,500  to  1,800  cubic  feet  of  fresh  air  per  hour. 

The  problem  of  the  ventilation  of  many  school  classrooms  is 

36 


55a  HYGIENE   AND    PUBLIC    HEALTH 

rendered  a  very  difficult  one  from  the  circumstance  that  a  series 
of  rooms,  considerably  overcrowded,  may  be  occupied  almost 
continuously  for  as  long  as  three  hours.  With  the  cubic  space 
available,  theoretically  the  air  should  be  changed  twelve  times 
an  hour,  winter  and  summer  alike,  if  it  is  to  remain  clean  and 
fresh;  meanwhile  the  temperature  of  the  classroom  has  to  be 
maintained  at  about  60°  F.  No  natural  agencies  are  sufficient 
under  these  circumstances.  Even  mechanical  ventilation,  pro- 
viding previously  warmed  air,  would  be  severely  taxed.  Short 
of  mechanical  ventilation,  the  situation  demands  {a)  suitable 
provision  for  warming  incoming  air;  (b)  cross  ventilation  of  the 
classrooms  through  hopper  windows  in  opposite  external  walls, 
and  frequent  occasions  for  flushing  the  rooms  with  fresh  air,  by 
opening  all  windows.  The  Plenum  method  of  ventilating  school 
premises  does  not  often  prove  a  success,  and  the  object-lesson  of 
permanently  closed  windows  is  a  bad  one  for  the  children. 

Educational  results  are  in  no  small  measure  dependent  upon 
the  air  results,  and  insufficient  air  renewal  in  school  classrooms 
is  an  important  item  in  determining  school  fatigue.  The  mental 
and  physical  depression  caused  by  the  insufficient  air  renewal 
cannot  be  explained  by  the  increase  in  carbonic  acid.  It  is 
doubtless  due  to  the  increased  temperature  and  humidity  of 
a  stagnant  atmosphere,  being  responsible  for  an  interference 
with  the  heat-regulating  mechanism  of  the  human  body.  It  is 
important,  therefore,  that  the  wet  and  dry  bulb  temperatures  of 
school  classrooms  should  be  continuously  recorded,  and  that  an 
effort  should  be  maintained  to  keep  the  dry  bulb  temperature 
between  56°  and  60°  F.,  and  the  wet  bulb  temperature  between 

53°  and  56°  F. 

The  walls  of  a  schoolroom  should  preferably  be  painted  or 

distempered,  so  that  they  can  be  washed,  and  any  colouring 

should  be  pale  and  subdued  (a  soft  greenish-grey  is  recommended) ; 

unnecessary  projections  (cornices,  etc.)  which  can  harbour  dust 

should  be  avoided. 

The  best  floors  are  made  of  hard  wood  in  narrow  planks,  with 

dovetailed  or  matched  joints;   these   may  be  beeswaxed   and 

polished  at  intervals,  and  should  always  be  swept  daily. 
All  staircases  should  be  at  least  5  feet  wide  and  fire-proof, 

and  faced  at  the  ground  floor  by  a  wide  door,  opening  outwards 

towards  the  street. 

Seats  and  Desks  should  be  arranged  parallel  with  one  another, 


SCHOOL   HYGIENE  563 

but  at  right  angles  with  the  windows.  To  avoid  shadows  when 
writing,  the  scholars  should  sit  with  the  left  hand  nearest  the 
main  windows,  so  that  the  chief  illumination  may  be  from  ttie  left 
front.  There  is  then  plenty  of  light  on  the  objects  on  the  desk, 
but  the  rays  are  not  reflected  directly  into  the  eyes  of  the  scholars, 
as  they  are  in  front  illumination  with  desks  facing  the  windows. 
If  the  predominant  light  comes  from  the  scholar's  right,  then  the 
shadow  of  his  hand,  while  writing,  falls  upon  the  paper. 

Desks  should  be  from  15  to  18  inches  broad,  and  should  slope 
at  an  angle  of  about  15°  for  writing  and  45°  for  reading.  The 
height  of  the  seat  from  the  ground  should  equal  the  length  of 
the  scholar's  legs  from  sole  of  foot  to  knee.  The  distance  of 
the  front  of  the  seat  from  a  perpendicular  line  let  fall  from  the 
edge  of  the  desk  should  never  exceed  i  inch.  The  perpendicular 
distance  of  the  seat  from  the  edge  of  the  desk  should  be  one- 
sixth  of  the  scholar's  height.  The  front  to  back  measurement 
of  the  seat  should  be  two-thirds  of  the  upper  leg,  and  the  front 
edge  of  the  seat  should  be  rounded.  Seats  and  desks  should  be 
adjusted  to  the  scholars  twice  yearly.  The  heights  of  scholars 
of  the  same  age  often  vary  as  much  as  10  inches.  Girls  grow 
most  between  12  and  14;  boys,  between  14  and  16.  There 
should  be  a  straight  back  to  the  seat,  with  a  curved  pad  or 
cushion  to  fit  into  and  support  the  small  of  the  back  and  loins 
to  the  level  of  the  shoulder  blades.  The  space,  on  a  common 
seat,  for  each  pupil,  should  equal  20  to  24  inches;  there  should 
be  10  inches  between  the  rows  of  seats,  and  the  rows  should 
not  extend  to  within  24  inches  of  the  wall.  From  each  seat  one 
should  be  able  to  see  the  sky.  There  should  be  a  small  raised 
platform  for  the  teacher.  Single  desks  and  seats  are  good, 
but  extravagant  of  floor-space.  Dual  seats  and  desks  may  be 
recommended.  The  Sheffield  type,  consisting  of  a  continuous 
desk  with  six  separate  seats,  is  far  preferable  to  a  long  common 
seat  and  desk. 

For  young  children  prolonged  posture  at  desks  is  bad,  and  the 
lesson  hours  should  be  broken  by  frequent  short  intervals  for  play. 

Blackboards  should  possess  dull  or  matt  surfaces;  they  must 
always  be  placed  in  a  good  light,  and  any  matter  shown  upon 
them  must  be  large  and  well  spaced. 

The  cloakrooms  must  be  capacious,  specially  heated  and 
ventilated.  Cloakrooms  should  be  cross- ventilated,  and,  io 
favour  air  renewal,  it  is  a  good  plan  to  put  wire-netting  in  the 


564  HYGIENE    AND   PUBLIC   HEALTH 

upper  panels  of  the  doors.  The  provision  should  be  in  the 
proportion  of  about  a  cloakroom  to  every  120  scholars.  The 
hanging-hooks  for  hats,  etc.,  should  be  from  15  to  18  inches  apart 
in  the  girls'  cloakroom,  and  at  least  9  inches  apart  in  the  boys' 
cloakroom ;  and  never  more  than  two  rows  of  hanging-pegs  should 
be  placed  upon  one  stand.  If  pegs  are  arranged  on  both  sides  of 
a  stand,  a  partition  of  fine  wire-netting  should  be  provided,  so 
as  to  keep  the  articles  on  the  two  sides  from  touching.  It  is  desir- 
able to  have  a  separate  cloakroom  for  each  classroom,  and  for  the 
pegs  to  be  numbered  and  scholars  made  to  keep  to  their  pegs. 

Covered  sheds  should  be  provided  for  recreation  when  it  rains ; 
and  if  space  is  unprocurable  on  the  adjoining  ground,  a  basement 
or  a  flat  roof  may  be  designed  to  meet  the  purposes  of  a  covered 
playground.  It  is  essential  that  the  scholars  should  receive 
plenty  of  physical  drill  and  exercise  in  the  open  air.  Under  a 
proper  system  of  medical  inspection,  commencing  physical  defects 
can  be  promptly  detected  and  remedied  by  appropriate  exercises. 

Suitable  closet  and  lavatory  provision  for  schools  should  pro- 
vide a  prompt  and  rapid  removal  of  excreta,  which  should  be 
inaccessible  to  the  scholars  after  deposition,  the  whole  installa- 
tion being  an  object-lesson  of  cleanliness  and  sanitary  practice. 
The  seats  of  water-closets  should  not  exceed  14  inches  in 
height  for  the  older  children,  and  from  11  to  12  inches  for  the 
youngest.  Water-closet  seats,  urinal  places,  and  lavatory  basins 
should  be  provided  in  the  proportion  of  at  least  five  of  each 
of  these  provisions  to  every  100  boy  scholars;  and  with  girls 
and  infants  the  water-closet  seats  should  amount  to  at  least 
7  per  cent,  of  scholars.  Generally  speaking,  there  are  too  few 
lavatory  basins  and  clean  towels  provided  in  our  schools.  In 
places  where  there  is  insufficient  water  for  flushing  urinals,  a 
good  cheap  and  lasting  material  for  coating  the  surface  which 
receives  the  urine  is  cement  coated  with  a  mixture  of  pitch 
and  tar.  In  country  schools,  where  water-closets  are  not  prac- 
ticable, privy  pits  should  always  be  replaced  by  pails  (as  where 
privies  exist  the  water-supply  is  very  frequently  from  adjacent 
wells),  and  earth-closets  provided.  After  use,  the  earth  is  best 
put  in  a  shallow  trench,  and  covered  over  with  3  or  4  inches  of 
soil,  and  the  soil  collected  from  this  site  should  be  stored  in  a 
drying-shed  in  small  quantities  prior  to  use.  One  of  the  modern 
types  of  trough  water-closet  or  latrine  {vide  p.  97)  is  sometimes 
used  for  schools,  but  the  flushing  provision  must  be  adequate 


SCHOOL   HYGIENE  5^5 

and  systematically  regulated.  Separate  closets  with  separate 
flushing  cisterns  are  to  be  preferred. 

All  dormitories  must  be  well  lighted  and  ventilated,  and  at 
least  400  to  500  cubic  feet  of  space  should  be  allowed  for  each 
scholar  under  12  years  of  age. 

The  drinking  cups  used  in  common  by  most  scholars  may  be 
a  means  of  communicating  disease,  such  as  diphtheria.  Many 
cups  should,  therefore,  be  supplied  in  place  of  the  one  or  two 
only  which  are  generally  provided.  Arrangements  should  also 
be  made  so  that  the  cups,  after  use,  are  continually  exposed  to 
flowing  water  during  play  hours;  and  the  cups  should  be  well 
cleansed  with  wet  sand  at  least  twice  a  week.  In  the  "  Crystal 
Stream  "  drinking  fountain  no  cups  are  necessary,  the  scholars 
directly  taking  the  water  as  it  issues  in  weak  upward  jets  from 
the  fountain. 

The  school  premises  should  provide  the  best  possible  hygienic 
environment  for  the  scholars,  and  should  present  an  object- 
lesson  of  cleanliness,  brightness,  good  taste,  and  of  scrupulous 
regard  for  all  sanitary  demands. 

The  teacher  is  not  concerned  with  such  matters  as  the  selec- 
tion of  site  and  the  planning  and  construction  of  premises,  but  can 
always  secure  the  best  sanitary  circumstances  under  the  existing 
conditions,  and  often  an  improvement  in  respect  of  these  conditions. 

The  effects  and  value  of  environment,  in  so  far  as  the  school- 
child  is  concerned,  are  of  a  twofold  nature — viz.,  the  physical 
and  educational.  The  educational  effect  and  value  is  capable 
of  further  subdivision  into  the  educational  effect  upon  the 
scholar  of  sanitary  precept  and  practice,  and  the  effect  of  the 
sanitary  environment  in  favouring  or  otherwise  the  mental  re- 
sponse, and  thereby  promoting  the  general  educational  results. 
Nothing  is  more  disabling  from  the  standpoint  both  of  the  teacher 
and  the  taught  than  foul  air;  and  the  effect  of  improving  the 
atmospheric  conditions  is,  in  the  classroom  as  in  the  workshop, 
to  improve  the  quality  and  amount  of  the  work  performed. 

Dirt  should  be  reduced  to  a  minimum,  as  by  clean  boots, 
clean  scholars,  clean  clothes,  and  chalk-troughs  to  blackboards. 
All  dirt-harbouring  arrangements  in  classrooms  should  be  reduced 
to  a  minimum — ^viz.,  cupboards,  shelves,  projections  (cornices, 
etc.),  platforms,  hangings.  All  decorations  on  walls  should  be 
easily  cleanable,  and  the  floors  and  walls  washable. 

At  the  end  of  the  school-day  doors  and  windows  should  be 


566  HYGIENE   AND    PUBLIC   HEALTH 

opened,  and  the  floors  swept  with  a  damp  broom,  or  after  appU- 
cation  of  wet  sawdust;  the  cloakrooms,  corridors,  etc.,  to  be 
included. 

Frequent  cleansing  and  disinfecting  precautions  are  more  par- 
ticularly called  for  in  the  infant  departments;  and  in  such  de- 
partments, upon  every  Saturday,  the  floors,  seats,  desks,  tables, 
and  window-sills  of  classrooms,  the  surfaces  of  cloakrooms  (in- 
cluding hat-pegs),  and  the  floors  of  halls  and  passages,  should 
receive  a  liberal  application  of  hot  water  containing  washing 
soda,  and  good  yellow  soap ;  finally,  the  washed  surfaces  may  be 
sprayed  with  a  little  disinfectant  solution.  In  making  the  choice 
of  a  disinfectant,  one  of  the  coal-tar  series  (izal,  cyllin,  etc.)  may 
be  selected,  which  is  capable  of  forming  a  fine  and  homogeneous 
emulsion  with  water,  and  possesses  a  carbolic  acid  coefficient  of 
at  least  12 ;  and  if  all  vertical  surfaces  are  sprayed  with  a  suffi- 
ciently fine  spray  from  below  upwards,  there  is  no  risk  of  any 
unsightly  stains  remaining  upon  walls,  etc.  It  is  hardly  neces- 
sary to  add  that  all  drinking-vessels  should  also  be  specially 
cleansed  once  a  week. 

Upon  alternate  Saturdays  the  whole  school  premises  should  be 
similarly  treated;  and  upon  every  fourth  Saturday  some  addi- 
tional items  should  be  included  in  the  scheme.  Then  all  wood- 
work to  a  height  of  6  or  7  feet  should  be  scrubbed ;  all  cupboards, 
ventilating  openings,  bookcases,  and  storerooms  should  be 
cleansed  and  sprayed;  and  maps,  books,  etc.,  should  be  taken 
outside  the  buildings  and  well  dusted. 

Dustless  oils,  if  used  fresh  and  applied  to  floor  surfaces  for 
several  days  before  these  surfaces  are  used,  tend  to  prevent  dust 
from  rising,  and  may  be  recommended.  The  material  costs 
about  five  shillings  a  gallon,  and  requires  to  be  applied  just 
before  the  commencement  of  each  school  term. 

All  waste-matters  upon  school  premises  should  be  burnt,  when 
possible;  and  failing  this,  promptly  deposited  in  covered, movable, 
metal  dustbins,  placed  out  of  reach  of  the  scholars. 

The  Disinfection  of  School  Premises  should  generally  be  per- 
formed by  the  Sanitary  Authority,  or  under  their  directions. 

2.  Notes  upon  the  School  Child. 
Under  the  Elementary  Education  Acts,  1876,  1899,  children 
from  5  to  14  years  of  age  must  attend  school;  and  under  the 
Elementary  Education  (Defective  and  Epileptic  Children),  and 


SCHOOL   HYGIENE  567 

(Blind  and  Deaf  Children)  Act,  1899  and  1893,  parents  must 
cause  abnormal  children  to  receive  education  up  to  16  years  of  age. 

The  Nervous  System  contains  the  machine  of  the  Mind;  it 
receives  and  interprets  various  sense-impressions,  regulates  all 
the  vital  functions  of  the  body,  and  controls  or  commands  the 
muscular  system.  It  should  therefore  be  the  cardinal  study  and 
concern  of  the  teacher. 

Wrong  or  slovenly  acts,  at  first  under  conscious  control,  may 
in  time  develop  into  subconscious  or  unconscious  habits.  Hence 
the  necessity  for  a  careful  attention  to  the  formation  of  good 
habits  of  thought  and  of  action,  and  for  the  early  correction  of 
bad  habits  or  tendencies. 

Even  in  health,  children  differ  greatly;  and  in  mental  educa- 
tion the  special  needs  of  the  individual  must  be  studied.  Per- 
manent injury  results  from  premature  or  excessive  stimulation  of 
the  brain  faculties,  by  impairing  the  whole  nervous  system,  and 
the  general  health  and  development  of  the  brain  and  body  suffer 
as  a  consequence;  it  is  therefore  opposed  to  all  the  objects  of 
education. 

Mental  Fatigue  is  less  due  to  overwork  than  to  wrong  work  at 
the  wrong  time  and  in  the  wrong  way.  It  is  accompanied  by  a 
slight  increase  in  the  cardiac  pulsations  and  blood-pressure;  by 
depressed  muscular  force  and  lessened  cutaneous  sensibility.  It 
may  be  measured  by  the  ergograph,  the  aesthesiometer,  and  the 
quality  of  any  set  work  (such  as  sums,  writing  to  dictation,  etc.). 

The  Symptoms  of  Brain  Fatigue  and  "  Over- pressure  "  are: 
{a)  Normal  and  Transient. — Yawning,  lassitude,  wandering  eyes 
and  inattention,  drowsiness,  fidgetiness,  slow  or  faulty  response 
to  words  of  command  and  questions,  head  balance  impaired, 
little  or  purposeless  movement. 

{b)  Continued  and  A  bnormal  {Over-pressure) .  —  Nerve-signs : 
Irregular  muscular  movements  —  chiefly  of  fingers,  eyes,  and 
mouth;  knitting  of  eyebrows  and  overaction  of  frontal  muscles; 
defective  muscular  balance  of  the  body  (especially  of  the  head) ; 
excessive  reflex  actions;  the  abnormal  position  of  the  hand  when 
held  out  in  front  at  word  of  command  (slight  drooping  of  thumb 
and  fingers);  stuttering;  restlessness  and  frequent  twisting  of 
body  and  neck.  Impairment  of  the  delicacy  of  touch  perception. 
Irritability,  grumbling,  and  excessive  sensitiveness  to  reproof. 
Facial  expression  of  exhaustion  or  anxietj^;  open  mouth;  lower 
eyelids    baggy    and    relaxed.      Languor,   listlessness,  headache. 


568  HYGIENE   AND    PUBLIC   HEALTH 

speedy  fatigue,  dulness  or  apparent  stupidity;  slow  or  inaccurate 
response  to  questions  or  commands;  excessive  drowsiness  or 
wakefulness;  night  terrors;  walking  in  sleep;  poor  bodily  de- 
velopment and  impaired  health  (pallor,  failure  of  appetite,  poor 
digestion,  feeble  circulation,  etc.).  It  is  a  predisposing  factor  to 
chorea,  hysteria,  and  epilepsy. 

Scholars  Especially  Liable  to  Suffer  from  Over- pressure : 
Delicate  nervous  children  (apt  to  be  irritable,  passionate,  and 
emotional);  constitutionally  weak  children;  anaemic,  badly  fed, 
rapidly  growing,  excitable  and  mentally  precocious  children. 
Those  exposed  to  bad  air  or  bad  conditions  of  study ;  bad  teach- 
ing and  unhealthy  home  conditions;  too  little  sleep  and  recrea- 
tion ;  defects  of  sight,  hearing,  etc. ;  excessive  strain  of  vision, 
etc. ;  the  period  of  puberty. 

The  Prevention  of  Brain  Fatigue:  A  Hygienic  Time-Table  is 
of  prime  importance — one  which  economizes  the  brain  energy 
and  directs  it  aright: — Short  lessons,  with  length  varying  with 
the  subject  (no  lesson  should  take  more  than  three-quarters  of 
an  hour);  a  proper  sequence  and  variation  of  subjects;  proper 
regard  to  stage  of  development  of  the  scholars  and  the  im- 
maturity and  instability  of  the  nervous  system  in  the  early  years 
of  school  life;  sufficient  intervals  for  rest,  recreation,  physical 
exercise,  and  food.  Fresh  air;  quiet  classrooms;  strict  limitation 
of  the  subjects  selected  for,  and  the  duration  of,  home-lessons. 
Home-work  not  to  take  more  than  one  hour ;  revision  work  only ; 
and  never  before  lo  years  of  age.  An  observant  teacher  will  see 
the  first  signs  before  exhaustion  results,  and  will  discover  when 
imperfections  of  vision  and  hearing  are  causing  strain  and  brain 
fatigue. 

Apparent  Dulness  may  be  due  to  defects  of  hearing  or  vision ; 
poor  nutrition  or  injudicious  teaching;  illness;  bad  air;  insuffi- 
cient recreation  and  sleep  (child-labour). 

Mentally  Defective  children  make  poor  progress  in  studies, 
and  show  unusual  peculiarities  of  temperament  and  of  moral 
perception. 

In  the  term  "  mentally  defectives  "  those  who  are  merely  dull 
and  backward  are  not  included.  The  former  are  incapable  of 
benefiting  much  from  ordinary  school  education ;  and,  in  their  own 
interests  and  in  the  interests  of  other  scholars,  they  should  be 
early  removed  to  special  institutions,  where  they  may  be  trained  in 
manual  work  and  kept  under  permanent  observation  and  control. 


SCHOOL    HYGIENE  569 

Children  suffering  from  word-blindness,  word-deafness,  and 
moral  imbecility  also  demand  special  provision  for  education. 

Chorea  (St.  Vitus's  Dance). — Occurs  chiefly  in  girls  between 
7  and  14.  Onset  gradual.  Constant  twitchings  of  body,  face, 
limbs  or  hands.  Things  are  dropped  because  of  impaired  control 
and  power  of  muscles.  The  child  is  generally  below  normal 
weight. 

Hysteria. — Especially  in  emotional  girls  at  age  of  puberty. 
Emotional  outbursts;  morbid  sensations  (ball  in  throat,  etc.); 
paralytic  symptoms,  etc.  Fits  are  of  gradual  onset,  with  sobs, 
laughter  or  other  emotional  display,  then  with  a  scream  the  girl 
falls  violently  convulsed  and  apparently  insensible;  she  rarely 
injures  herself,  and  never  bites  the  tongue. 

Epilepsy. — Momentary  palsy  of  face,  then  sudden  uncon- 
sciousness, stiffening  of  body,  biting  of  tongue,  hands  clenched, 
and  convulsive  movements  of  limbs  and  muscles  of  face  (face 
distorted  and  blue  from  congestion).  The  fit  is  followed  by 
drowsiness. 

The  physiological  necessity  for  adequate  rest  and  recreation 
and  good  physical  training  must  not  be  ignored.  These  reduce 
the  number  of  cases  with  signs  of  brain  disorderiiness  and  the 
number  of  dull  children. 

The  importance  of  quality  and  quantity  of  sleep  as  affecting 
the  working  capacity  of  the  brain  cannot  be  exaggerated. 

Sleep  is  necessary  for  the  growth  and  repair  of  both  physical 
and  mental  tissues,  and  deficient  sleep  is  a  great  factor  in  mental 
dulness  and  malnutrition. 

The  quantity  of  sleep  which  is  desirable  during  school  ages  is 
as  follows: — • 

Years  of  Age.  Hours  of  Sleep. 

4-8  ..  ..  ..  12 

9—12  .  .  .  .  . .  II 

12—14  •  •  •  •  •  •      9-^0 

14-20  .  .  .  .  .  .  9 

A  well- ventilated  bedroom  (open  windows),  absolute  quiet, 
darkness,  and  a  warm  bed,  favour  sound  and  refreshing  sleep. 

The  development  of  the  nervous  system  of  a  child  is  one  of 
great  importance  from  the  educational  standpoint.  In  child- 
hood, especially  from  3  to  10  years  of  age,  the  nervous  system 
is  unstable,  rapidly  developing  and  easily  tired.     Since  mind 


570  HYGIENE    AND    PUBLIC   HEALTH 

and  body  act  and  react  upon  each  other,  the  body  suffers  if 
excessive  demands  are  made  upon  the  brain,  and  the  brain 
suffers  if  excessive  demands  are  made  upon  the  body.  The  coarse 
large  movements  of  early  childhood  slowly  become  finer  with  the 
gradual  development  of  the  complex  co-ordinations  necessary  for 
fine  movements.  Thus,  up  to  5  years  of  age  a  child  should  be 
educated  through  the  senses  and  its  activities;  then  the  memory 
should  be  developed,  and  good  habits  and  training  cultivated. 
After  10  years  of  age  the  child's  reasoning  powers  and 
imagination  develop.  Probably  the  chief  period  of  character 
formation  is  from  5  to  8. 

Psychologically,  it  is  to  be  remembered  that  the  young  child 
is  very  imitative,  craves  for  approval,  and  seeks  to  emulate;  it 
is  naturally  curious,  and  its  activities  are  incessant ;  these  latter 
must  be  controlled  and  directed  to  useful  educational  ends — 
physical,  moral,  and  mental.  Any  tendency  to  such  defects  as 
selfishness  and  falsehood  must  be  early  checked,  always  remem- 
bering that  the  will  to  do  comes  first,  and  inhibitory  powers  (the 
will  not  to  do)  later;  hence  the  truth  in  the  old  pedagogical 
maxim,  "  Don't  say  don't." 

VisiON.^ — -In  children  the  eye  is  relatively  short  from  before 
backwards,  and  the  child  has  to  compensate  for  this  by  muscular 
effort,  which  involves  eye  fatigue  and  nervous  strain;  moreover, 
the  still  developing  nerves  of  the  retina  are  easily  tired.  In 
early  life  the  eyes  are  soft  and  plastic,  and  readily  yield  to  con- 
ditions favouring  defective  vision. 

The  eyesight  of  at  least  20  per  cent,  of  scholars  is  defective, 
and  in  10  per  cent,  it  is  seriously  defective.  Affections  of  vision 
are,  therefore,  among  the  most  common  hindrances  to  school  work. 

The  strain  of  correction  where  vision  is  faulty  leads  to  eye 
fatigue,  which  causes  brain  fatigue  and  diminished  perception; 
furthermore,  brain  fatigue  leads  to  general  constitutional  results. 

The  causes  of  eyestrain  are:  Too  continuous  eye-work,  and  a 
bad  time-table;  fine  and  indistinct  work,  and  work  brought  too 
near  the  eyes;  bad  or  faulty  lighting  of  room;  bad  posture  in 
reading  and  writing.  Predisposing  causes  are  badly  ventilated 
and  overheated  rooms,  debility  and  poor  nutrition  of  scholar. 

The  printing,  etc.,  of  school  books  is  of  great  importance. 

UOUDlG      piCcl       should  be  selected  for  infants. 
and  "pica  leaded  "  for  older  school  children. 


SCHOOL   HYGIENE  57 T 

The  Symptoms  of  Defective  Vision  are:  Headache,  generally 
frontal,  worse  at  night  and  reheved  by  sleep;  a  sense  of  fulness 
in  head;  redness  of  eyeballs  and  eyelids;  watering  of  eyes; 
blinking;  partial  closing  of  eyes  when  looking  at  distant  objects; 
frequent  rubbing  of  eyes;  heat  and  pain  in  eyes;  dizziness,  and 
sometimes  nausea  or  even  vomiting;  squint;  irritability, 
neuralgia,  and  impaired  general  health;  books  held  within 
12  inches  of  the  eyes;  confusion  of  letters — especially  h  and  b,  e 
and  c;  inattention  and  apparent  stupidity. 

Short-Sight  (myopia)  is  rare  before  8  years  of  age,  and  in- 
creases greatly  as  we  pass  from  lower  to  higher  grades  at  school ; 
hence  an  illustration  of  the  injurious  effect  of  school-life  upon  the 
scholars'  eyesight.  This  condition  is  due  to  the  "  long  eye  " 
with  the  too  distant  retina;  and  hence  concave  lenses  are 
needed. 

It  is  most  liable  to  develop  in  delicate  children  with  poor 
muscular  and  nervous  tone,  and  especially  when  parents  are 
myopic.  Convalescence  from  acute  fevers,  bad  air,  bad  habits, 
night  work,  overheated  rooms,  favour  the  condition.  Prominent 
eyes  with  large  pupils  suggest  myopia. 

Bad  posture  during  reading  and  writing  may  cause  myopia, 
and  myopia  may  cause  bad  posture. 

Long-Sight  (hypermetropia).- — -This  condition  is  due  to  the 
"  short  eye  "  with  the  too  near  retina;  and  hence  convex  lenses 
are  needed.  This  is  the  most  common  eye  defect  in  young 
children.  Eyestrain  is  continuous  in  school,  and  there  is  no 
relief  by  bringing  objects  nearer,  as  in  short-sight.  Small  deep- 
set  eyes,  with  contracted  pupils,  and  red,  watery  eyes,  suggest 
long  sight. 

Astigmatism. — Blurred  images  and  indistinct  vision  at  any 
distance,  due  to  eyeball  (especially  the  cornea)  being  asym- 
metrical, and  thus  part  of  object  is  seen  out  of  focus.  The  con- 
dition is  generally  congenital,  and  often  exists  with  long-  or 
short-sight.  The  child  who  peers  or  who  looks  obliquely 
probably  has  astigmatism. 

Squint  is  generally  due  to  the  focussing  power  of  the  two  eyes 
being  unequal  and  to  overstrain  of  certain  eye  muscles. 

Squint  usually  comes  on  at  about  3  years  of  age;  and  the  con- 
vergent squint  of  children  is  generally  associated  with  long-sight. 
A  squinting  eye  is  a  non-seeing  eye,  and  early  treatment  is 
necessary  to  prevent  serious  complications. 


572  HYGIENE    AND   PUBLIC   HEALTH 

Glasses  do  not  weaken  the  eyes,  but  strengthen  them;  they 
conserve  the  sight,  prevent  headache,  etc. ;  and  prevent  squints, 
or  may  even  cure  them. 

Co  lour- Blindness. — Most  colour-bhnd  people  cannot  tell  red 
from  green,  and  call  them  shades  of  the  same  colour. 

Ophthalmia  and  Conjunctivitis. — Redness  of  eyes,  crusts  on 
margins  of  lids,  with  loss  of  eyelashes;  extreme  sensitiveness  to 
light;  excessive  watering  of  eyes;  formation  and  discharge  of 
yellow  matter. 

Habit-Spasm. — This  is  due  to  the  spasmodic  contraction  of  the 
ciliary  muscle  in  the  direction  of  the  muscular  movement  which 
has  predominated  for  some  time.  It  is  a  visual  "  cramp,"  most 
frequently  observed  in  nervous  girls  of  over  ii  years  of  age; 
and  rest,  fresh  air,  and  good  feeding  are  demanded. 

Congenital  Word-Blindness. — In  this  condition  the  visual  recog- 
nition by  the  eye-brain  is  abnormally  slow  or  congenitally  defec- 
tive. The  scholar  has  no  visual  memory  for  words  or  letters, 
or  the  brain  acts  slowly  in  interpreting  such  objects  as  letters. 
The  condition  causes  dulness  in  learning  to  read  and  write. 

The  vision  is  tested  by  Snellen's  cards,  which  contain  letters 
of  chminishing  size  from  above  downwards.  By  these  cards 
normal  vision  can  read  without  effort  the  letters  on  the  line 
marked  6,  when  the  child  stands  at  the  standard  distance  of 
6  metres,  or  20  feet.  Normal  vision  is  expressed  by  putting  6 
as  a  numerator,  and  the  number  opposite  the  smallest  type  which 
the  child  can  read,  at  the  standard  distance  of  6  metres,  as  the 
denominator;  hence  normal  vision  is  expressed  as  ^.  If,  however, 
the  child  could  only  read  the  type  of  the  line  marked  12,  its 
vision  would  be  expressed  as  y'V,  or  one-half  of  normal.  yW  is 
often  advocated  as  the  standard  for  the  elementary  school  child ; 
and  it  is  only  when  the  vision  is  worse  than  this — say  one-third 
normal,  or  less — that  the  child  is  measured  for  spectacles.  Vision 
should  be  tested  on  admission  to  school,  and  once  during  each 
year  of  school  attendance,  assuming  the  child  to  be  over  6  years 
of  age  and  capable  of  interpreting  what  it  sees.  Any  facial 
distortion  or  oblique  or  advanced  position  of  the  eye  must  be 
noted;  one  eye  should  be  tested  at  a  time,  and  if  the  child  already 
wears  glasses,  the  test  should  be  applied  with  the  glasses  on. 

Colour-blindness  may  be  sufficiently  tested  for  school  purposes 
by  means  of  a  few  skeins  of  bright  green  wool,  mixed  with  a  mass 
of  confusion  colours  among  which    reds  figure  prominently.     If 


SCHOOL  HYGIENE  573 

the  child  can  pick  out  all  the  skeins  wiiich  match  a  pale  green 
skein,  vision  may  be  pronounced  normal  in  this  respect. 

To  conserve  vision,  school  hooks  should  meet  the  following 
requirements:  Sufficient  thickness  of  paper;  type  large,  clean 
cut,  thick-faced,  and  well-defined;  letters  and  lines  well  spaced, 
and  good  margins  to  the  pages;  ink  black;  paper  white  or  tinted 
yellow;  no  type  allowed  which  necessitates  the  holding  of  the 
book  at  a  less  distance  than  12  inches.  Best  types  are  "  double 
pica  "  for  very  young  children,  "  pica  leaded  "  for  children  6  to 
II  years,  and  "  small  pica  leaded  "  for  the  older  children;  small 
type  annotations  disallowed;  the  lines  of  the  school  book  not  to 
exceed  4  inches  in  length.  It  is  desirable  that  a  standard  of 
book  production  for  school  purposes  should  be  established.  In 
school  illustrations  placed  upon  walls  there  should  be  a  bold, 
firm  treatment  of  a  few  objects  only. 

Hearing. — Generally  from  12  to  20  per  cent,  of  scholars  are 
defective  in  their  hearing.  The  Signs  of  Defective  Hearing  and 
Ear  Disease  are:  The  child  misses  spoken  words  or  directions; 
strained  attention  in  class;  inattention  and  apparent' stupidity; 
early  exhaustion  from  lessons;  mouth-breathing;  earache;  head- 
ache; discharges  from  ears;  giddiness;  impaired  general  health. 

The  Causes  of  Defective  Hearing  are:  Adenoids  and  enlarged 
tonsils;  inflammation  or  abscess  in  the  middle  ear  from  inflam- 
mation or  disease  of  nose  or  throat  (catarrh,  measles,  scarlet 
fever,  diphtheria,  etc.) ;  wax  in  ears.  It  is  found  that  among 
school  children  who  are  deaf-mutes  that  some  60  per  cent,  were 
born  deaf. 

On  admission  to  school  the  hearing  should  be  tested,  and 
subsequently  once  a  year.  The  testing  is  always  difficult,  and 
many  tests  have  been  suggested,  such  as  the  whisper  test,  the 
stop-watch  test,  the  tuning-fork  test,  the  audiometer,  and  acu- 
meter.  Probably  the  best  test  is  the  forced  expiratory  whisper 
(stage  whisper)  at  the  standard  distance  of  20  feet.  The  child 
must  not  see  the  lips,  and  so  should  be  placed  with  the  back 
to  the  teacher;  both  ears  should  be  separately  tested,  the  child 
being  made  to  repeat  numbers.  In  some  noisy  classrooms  it  is 
necessary  to  examine  several  apparently  normal  children,  and 
get  these  to  estabhsh  the  standard  distance  for  the  test  in  that 
particular  room. 

Through  the  auditory  word-centre  the  child  grows  to  associate 
words   with  ideas;   then   the   motor  word-centre   (for  speech) 


574  HYGIENE    AND    PUBLIC   HEALTH 

develops;  and  the  two  becoming  linked  up,  the  child  imitates  the 
sounds  that  it  hears.  The  visual  word-centre  develops  later, 
and  becomes  linked  up  with  the  auditory  and  motor  word- 
centres  for  speaking  and  writing;  and  then  by  memory  (the 
storage  of  impressions)  the  child  can  name  and  write  printed  or 
heard  words,  and  recall  the  object  to  which  the  word  relates.  A 
child  suffering  from  word-blindness  has  not  this  visual  word- 
centre  properly  developed,  and  one  suffering  from  word-deafness 
has  a  defect  in  the  auditory  word-centre;  but  vision  and  hearing 
in  all  other  respects  may  be  normal. 

Early  attention  to  defects  of  sight  and  hearing  will  either  lead 
to  a  cure  or  will  prevent  matters  going  from  bad  to  worse,  and 
thus  save  the  scholars  from  grave  educational  losses  and  dis- 
abilities in  after-life. 

Exercise. — The  muscles  contain  in  their  substance  about  one- 
quarter  of  the  blood  of  the  whole  body;  their  action  promotes  the 
circulation  of  the  blood,  and  hence  plays  an  important  part  in 
promoting  the  general  nutrition.  During  muscular  exercise  the 
force  and  frequency  of  the  heart's  action  are  increased;  the 
respirations  are  more  frequent  and  deep;  and  the  functional 
activity  of  the  organs  of  digestion  and  excretion  (skin,  kidneys, 
and  bowels)  is  increased.  The  development  of  the  nervous  and 
muscular  systems  are  interdependent,  and  both  are  promoted 
by  muscular  activity.  Hence  muscular  exercise  promotes  an 
active  circulation  of  the  blood  generally  throughout  the  body; 
develops  the  muscles  and  improves  the  carriage  and  symmetry 
of  the  body;  trains,  through  the  nervous  system,  the  action  of 
the  muscles  and  the  "muscular  sense";  promotes  the  sym- 
metrical development  of  the  brain,  and  healthy  and  vigorous 
brain  power;  and  generally  improves  body  nutrition  and  main- 
tains the  body  functions  in  health. 

Furthermore,  physical  exercises  at  school  counteract  the 
harmful  tendencies  of  bad  posture,  and  reduce  the  number  of 
cases  of  nervous  disturbance  among  scholars.  They  can  be  made 
to  correct  faulty  and  defective  conditions  in  the  scholar's  develop- 
ment, and  also  any  acquired  bad  habits  of  posture  or  deport- 
ment; to  provide  a  profitable  diversion  from  brain  work;  to  aid 
in  school  discipHne  and  develop  quahties  of  alertness,  decision, 
and  activity. 

All  exercise  should  be  taken  in  the  open  air  when  possible^ 
and,  when   under  cover,  the  conditions  should  be  made  to  ap- 


SCHOOL   HYGIENE  575 

proximate  to  open-air  conditions  as  mucli  as  possible;  all  clothing 
should  be  light  and  loose;  boots  must  not  be  stiff  and  tight 
round  the  ankles;  flannel  or  woollen  garments  should  be  worn 
next  to  the  skin;  excessive  fatigue  from  too  violent  and  pro- 
longed exertion  should  always  be  avoided,  as  otherwise  too  great 
a  strain  is  thrown  upon  the  heart ;  only  gentle  exercise  should  be 
taken  directly  after  a  meal.  Physical  exercises  should  be  gradu- 
ated to  suit  the  ages  of  the  scholars;  sickly  and  deformed  children, 
convalescents  from  diphtheria,  etc.,  and  those  who  have  walked 
long  distances  to  school,  require  special  consideration  and 
specially  selected  exercises;  the  exercises  must  not  be  too  ex- 
acting between  the  ages  of  13  and  16,  and  in  the  case  of  rapidl}' 
growing  and  overgrown  children;  such  faults  as  holding  the 
breath,  stooping  or  contracting  the  chest,  and  the  uneven  per- 
formance of  the  exercises,  must  be  corrected;  suitable  precau- 
tions must  be  taken  to  avoid  chills  after  exercise. 

For  scholars  over  8  years  of  age  the  school  curriculum  should 
include  a  scheme  of  organized  games,  those  being  selected  which 
are  best  calculated  to  develop  the  physical,  mental,  and  moral 
qualities  of  the  scholar.  In  addition,  certain  drill  exercises  are 
needed;  and  after  fourteen  years  of  age  gymnastics  are  desirable 
— especially  when  any  particular  group  of  muscles  needs  training 
or  strengthening. 

Better  results  are  obtained  from  short  daily  exercises  than 
from  longer  exercises  at  greater  intervals. 

Ling's  Swedish  system  of  exercises  has  for  its  object  the 
harmonious  development  of  the  skeleton,  the  muscular  system, 
and  the  internal  organs.  Each  movement  is  required  to  be  a 
brisk,  deliberate,  and  forcible  response  to  the  word  of  command ; 
and  special  apparatus  is  used,  including  wall-bars,  vertical 
ladders,  horizontal  ladders,  climbing  ropes,  rope  ladders,  horse, 
vaulting-box,  etc. 

Folk-dances  are  to  be  encouraged,  inasmuch  as  they  inspire 
a  love  of  physical  exercises,  and  develop  neuro-muscular  co- 
ordination, and  are  graceful  accomplishments. 

On  the  subject  of  physical  exercises  the  revised  syllabus  of 
physical  exercises  for  public  elementary  schools,  issued  by  the 
Board  of  Education,  may  be  very  profitably  consulted. 

There  is  much  to  be  said  in  favour  of  occasional  five-minute 
"  fresh-air  drills  "  in  school  classrooms.  To  this  end  certain 
"  health  monitors,"  appointed  each  week,  should  be  told  to  open 


576  HYGIENE    AND    PUBLIC   HEALTH 

all  windows  and  doors,  when  a  deep-breathing  exercise  is  main- 
tained for  about  two  minutes.  For  the  deep-breathing  exercise 
the  following  orders  are  given:  "Stand  erect!"  "Attention!" 
"Hands  on  hips!"  "Shut  mouths!"  "Breathe  in!"  (slowly 
given),  "  Breathe  out !"  (slowly  given).  The  "  Breathe  in  !"  and 
"  Breathe  out !"  are  repeated  six  times.  After  a  few  moments' 
pause,  the  exercise  is  repeated  another  six  times.  This  is  then 
followed  by  a  smart  physical  drill  of  symmetrical  arm  move- 
ments for  three  minutes.  During  these  exercises  the  scholar 
must  stand  erect,  and  the  head  must  not  be  thrown  back. 

Posture  and  Deformity. — In  early  hfe  the  bones  consist 
partly  of  cartilage  or  gristle,  and  therefore  readily  yield,  but 
ossification  is  practically  complete  at  12  years  of  age;  hence  a 
child,  under  favouring  conditions,  may  become  deformed.  A 
bad  position,  for  instance,  remaining  uncorrected  for  some  time, 
may  in  certain  children  lead  to  peimanent  deformity,  which 
displaces  and  compresses  important  organs.  The  children  who 
are  most  liable  to  such  deformities  are  rickety,  strumous,  debili- 
tated and  overgrown  children,  with  poor  muscular  tone  ;  and 
especially  such  children  between  the  ages  of  9  and  14. 

Rickety  Children  may  generally  be  distinguished  by  their  large 
heads  and  prominent  foreheads,  small  stature,  "  pigeon-breasts," 
bow-legs,  enlarged  abdomens,  and  they  may  be  knock-kneed  or 
flat-footed  and  give  evidence  of  poor  nutrition. 

Rickety  children  are  generally  to  be  found  in  the  infants' 
department.  It  is  important  that  they  should  not  be  allowed  to 
stand  too  much  and  that  bad  posture  should  be  corrected.  Such 
children  specially  require  regular  physical  exercises  and  fresh  air. 

Strumous  Children  are  often  beautiful  children  with  fair  deli- 
cate skins;  they  are  especially  prone  to  glandular  trouble  and 
are  often  narrow-chested. 

The  causes  of  Bad  Posture  at  school  are :  Too  protracted  work 
at  desks — especially  writing  (faulty  school  programme) ;  bad 
seats  and  desks;  bad  school  books;  bad  lighting  of  classrooms; 
bad  habits;  too  fine  and  too  near  work;  short-sight;  ill-health 
and  bodily  weakness. 

The  evil  results  follow  if  seats  are  too  high,  too  low,  too  narrow 
or  too  flat,  and  have  no  spinal  support;  if  desks  are  too  high, 
too  low,  too  narrow,  and  have  faulty  slopes;  if  too  great  distance 
between  seats  and  desks,  or  seats  and  desks  too  near.  The  seat 
and  desk  should  be  adjusted  to  each  scholar  at  least  twice  a  year. 


SCHOOL   HYGIENE  577 

The  results  of  bad  posture  are:  Compression  of  cliest,  and 
interference  witli  free  movements  of  the  chest  in  respiration  and 
with  the  circuhition  of  the  blood;  interference  with  the  functions 
of  abdominal  organs;  round  or  uneven  shoulders  and  lateral 
curvature  of  spine;  bad  habits  of  body  carriage;  early  fatigue; 
short-sight  and  headache. 

Spinal  Curvature — Lateral. — Is  especially  prevalent  in  girls  of 
about  the  age  of  puberty.  First  a  drooping  of  one  shoulder 
may  be  noted,  and  then  the  shoulders  or  hips  (generally  the  right 
only)  "  grow  out  ";  backache,  lolling,  and  stooping  occur;  later 
the  crooked  spine  is  very  evident.  Posterior. — Common  in 
weakly  and  rickety  children;  round  shoulders  result.  Angular. — 
Due  to  disease  (caries)  of  spine ;  cannot  straighten  back ;  pain  on 
percussion.  Spinal  curvature  leads  to  displacement  and  com- 
pression of  important  organs,  and  though  generally  preventable 
at  school  ages,  is  extremely  difficult  of  cure. 

With  Good  Posture  the  head  is  erect  and  poised  directly  above 
the  spine,  and  the  two  shoulders,  hips  and  elbows,  are  level; 
if  sitting,  the  thighs  are  at  right  angles  with  the  trunk  and  the 
forelegs  are  at  right  angles  with  the  thighs.  If  seat  and  desk 
fit  the  scholar  he  sits  squarely  in  this  attitude,  with  his  work  in 
front  of  him;  his  posture  is  symmetrical,  and  therefore  his  muscles 
are  acting  equally  and  are  well-balanced,  and  this  ensures  a 
minimum  of  muscular  effort  and  discomfort.  Muscular  effort  is 
involved  in  standing,  and  to  a  less  extent  in  sitting  still. 

The  Respiration  in  children  must  be  free  from  any  obstruc- 
tion— whether  in  the  nose  or  throat,  or  from  interference  with 
free  chest  movements,  as  by  tight  clothing  or  bad  posture. 

The  signs  of  obstruction  to  respiration  in  the  nose  and  throat 
are:  Open  mouth;  muffled  nasal  voice;  often  a  vacant  and  un- 
intelligent expression;  snoring;  frequent  colds  and  nasal  dis- 
charge; breathing  not  free  and  often  noisy;  mental  dulness; 
deafness;  cough;  nostrils  compressed  and  poorly  developed  (if 
long-standing);  and  if  child  rickety,  often  "  pigeon-chested." 

The  value  of  deep-breathing  exercises  is  very  great,  especially 
in  the  growing  child.  They  assist  the  circulation  of  blood,  and 
develop  the  chest  capacity;  they  are  also  of  value  in  children 
with  early  adenoids  and  spinal  curvature,  or  who  stammer. 

The  advantages  of  cultivating  a  habit  of  nasal  breathing  are: — 
The  individual  is  less  liable  to  sore  throats  and  consequent  ear 
trouble;  dust  or  dirt  in  the  inspired  air  gets  filtered  off  to  a 

37 


578  HYGIENE   AND    PUBLIC    HEALTH 

great  extent  in  the  nose,  from  which  it  can  be  dislodged  without 
being  either  inhaled  or  swallowed;  and  the  nasal  secretion  pos- 
sesses some  power  of  inhibiting  the  growths  of  micro-organisms 
which  may  be  retained  on  the  mucous  membrane. 

Nasal  discharges  may  signify:  Catarrh,  influenza,  measles, 
adenoids,  diphtheria,  scarlet  fever,  or  ulceration  or  foreign  body 
in  the  nose. 

Breathing  foul  air  for  a  short  time  may  cause :  Languor,  mental 
dulness,  drowsiness,  yawning,  headache,  faintness,  nausea,  and 
even  vomiting;  but  breathing  foul  air  day  after  day  gives  rise 
to  serious  and  lasting  consequences,  including:  Debilitation;  loss 
of  tone  and  vitality,  and  therefore  poorness  of  appetite  and  im- 
paired digestion;  increased  liability  to  infectious  disease;  throat 
and  lung  complaints  and  consumption;  anaemia  or  poorness  of 
blood;  indications  of  impure  blood,  in  bad  complexion,  skin 
eruptions,  etc.     It  is  also  favourable  to  rickets. 

By  the  Circulation  of  the  Blood  the  following  objects  are 
achieved: 

Food  and  oxygen  are  conveyed  to  the  tissues  for  their  nourish- 
ment, growth  and  repair;  the  heat  (which  is  generated  in  the 
muscles  and  the  glands)  is  distributed  over  the  body;  and  waste 
matters  are  carried  from  the  tissues  to  the  excretory  organs. 

The  following  symptoms  in  scholars  probably  indicate  some 
departure  from  the  normal  in  either  the  composition  of  the  blood 
or  the  heart's  action.  Extreme  pallor — especially  of  lips,  gums 
or  the  inside  of  eyelids  (anaemia);  languor;  irritability;  faint- 
ness; disinclination  to  play  and  breathlessness  on  exertion; 
emaciation;  coldness  of  extremities;  palpitation  or  pain  over 
region  of  heart;  blueness  of  nose,  ears  or  finger-tips. 

Children  with  poor  blood  and  defective  circulatory  systems 
are  impaired  mentally  and  physically.  Their  special  needs  call 
for  some  reduction  in  the  mental  and  physical  work  demanded 
of  normal  scholars;  suitable  exercises  (including  deep-breathing 
exercises)  will  aid  the  circulation;  but  to  maintain  the  blood 
good  in  quality  and  quantity  proper  food  and  abundance  of 
fresh  air  are  necessary.  Bad  feeding  and  bad  living  predispose 
to  scurvy  and  purpura — conditions  which  are  characterized  by 
haemorrhages  about  the  body. 

The  causes  of  Enlargement  of  the  Lymphatic  Glands  arc : 
Pediculi,  wounds,  sores  and  eruptions  on  skin  or  scalp;  throat 
or  ear  trouble;  carious  teeth;  scrofula  or  struma. 

Enlarged  lymphatic  glands  may  be  observed  or  felt  up  the 


SCHOOL   HYGIENE  579 

sides  of  the  neck  (cervical),  at  the  upper  and  back  part  of  the 
neck  (occipital),  in  the  groins  (inguinal),  and  immediately  above 
the  internal  condyles  of  the  humerus. 

It  is  important  to  keep  The  Skin  clean.  Dirt  impedes  the 
important  work  of  the  skin  and  throws  extra  work  upon  other 
organs;  it  favours  skin  blemishes  (blackheads,  pimples,  etc.), 
boils,  abscesses,  and  the  harbouring  of  parasites  and  germs  of 
disease. 

It  is  most  important  to  develop  cleanly  habits  in  school 
children.  The  hair,  face  and  hands  should  always  be  clean,  and 
the  nails  kept  short.  A  weekly  wash  in  hot  water  and  a  weekly 
change  of  underclothing  are  necessary  to  these  ends. 

Warm  baths  cleanse  the  skin  and  thus  promote  its  healthy 
functions.  Cold  baths  have  a  stimulating  and  tonic  effect  and 
reduce  liability  to  catch  colds.  Swimming  baths  provide  physical 
exercise,  promote  health,  and  afford  opportunities  of  acquiring 
a  useful  accomplishment.  A  bathman  or  instructor  should 
always  be  present. 

Warm  baths  should  be  from  95°  to  100"  F.  Hot,  105°  to 
110°  F.     Cold,  55°  to  60°  F.     Swimming  baths,  about  70°  F. 

For  schools  the  advantages  of  shower  baths  over  slipper  baths 
are:  Fresh  clean  water  constantly  applied;  more  economical  of 
time;  cheaper;  danger  of  infection  reduced;  more  stimulating. 
A  weekly  shower  bath  (5  to  10  minutes)  with  soap  and  warm 
water,  at  about  90°  F.,  is  desirable. 

The  benefits  of  school  baths  as  testified  by  school  teacherb 
and  doctors  are:  Greater  cleanliness  of  scholars'  underclothing; 
reduction  in  skin  diseases  and  vermin;  increased  self-respect  of 
scholars;  good  moral  influence  on  homes;  better  school  work 
claimed  by  some. 

It  is  of  great  importance  to  keep  the  Hair  and  Nails  clean. 
The  head  louse  {Pedicuhis  capitis)  is  a  greyish-white  insect,  the 
female  laying  numerous  eggs  (nits),  which  are  attached  to  the 
shafts  of  the  hair,  usually  near  the  skin,  by  a  gluey  substance. 
The  embryos  in  the  nits  take  some  8  to  10  days  to  incubate. 
Much  irritation  is  caused  by  lice,  which  suck  blood  after  biting; 
and  the  consequent  scratching  causes  sores  and  scabs.  When 
there  are  lice  (pediculi)  and  their  eggs  (nits)  in  the  hair,  the  child 
is  generally  pale  and  poorly  nourished,  dirty  and  miserable;  a 
peculiar  dry  look  about  the  hair,  and  scratch  marks  on  fore- 
head or  behind  ears.  Lice  or  nits  will  be  seen  more  especially 
when  the  hair  behind  the  ears  is  raised  and  examined,   when 


580  HYGIENE   AND    PUBLIC    HEALTH 

the  scalp  is  often  dirty,  with  sore  places  upon  it.  (Nits  are 
smoky-brown,  oval,  glistening  bodies,  and  should  be  looked 
for  about  half  an  inch  from  the  roots  of  hairs.) 

Where  there  are  sore  places  or  scabs  the  hair  should  be  cut 
short,  and  in  the  case  of  scabs  a  linseed  or  bread  poultice  should 
be  applied.  The  head  may  be  cleansed  from  lice  by  the  applica- 
tion of  carbolic  or  parafhn  oil  overnight,  and  a  thorough  wash- 
ing of  the  head  with  soft  soap  and  water  the  next  morning,  after 
which  the  hair  should  be  combed  thoroughly  with  a  fine  tooth- 
comb  repeatedly  dipped  in  vinegar.  This  treatment  should  be 
repeated  daily,  when  the  worst  head  should  be  completely  freed 
of  lice  in  the  course  of  a  week.  Where  there  is  difficulty  in 
keeping  a  child's  head  clean,  the  hair  should  be  worn  short. 

Ringworm. — Is  most  common  between  5  and  10  years  of  age. 
It  gives  rise  to  one  or  more  circular  patches  on  the  top  of  the 
child's  head;  the  patches  are  covered  with  fine  white  powdery 
scales,  and  the  hairs  on  the  part  are  dull  and  mostly  broken  off. 
The  treatment  is  difficult,  and  should  be  under  medical  direction. 

Ringworm  of  the  scalp  is  often  spread  by  the  caps  of  scholars; 
and  this  is  one  of  the  reasons  why  each  child  should  have  a 
numbered  peg  in  the  cloakroom  and  children  should  never  ex- 
change caps.  It  is  difficult  to  tell  when  a  child  has  completely 
recovered  from  this  disease,  and  children  frequently  return  to 
school  too  soon.  All  cases  should  be  regarded  as  infectious 
when  broken-off  stumps  of  hair  are  to  be  observed  with  a  lens, 
and  when  such  stumps,  after  removal  and  washing  with  ether 
and  mounting  for  a  few  minutes  in  10  per  cent,  potash  solution, 
show  spores  of  ringworm.  Owing  to  the  prolonged  loss  of  educa- 
tion frequently  entailed  by  this  complaint,  the  educational 
authorities  of  some  large  cities  have  instituted  special  ring\vorm 
classes. 

Ringworm  of  body  is  most  common  on  the  face,  side  of  neck, 
wrists  and  hands.  Like  ringworm  of  the  scalp,  it  has  a  tendency 
to  relapse,  and  to  recover  spontaneously  at  the  end  of  the  school 
period. 

Impetigo  Contagiosum. — This  condition  is  distinguished  by  the 
presence  of  small,  isolated,  flat  vesicles,  generally  first  to  be 
observed  upon  the  face.  The  contents  of  the  vesicles  become 
milky  and  then  purulent,  and  after  a  few  days  crusts  or  scabs 
form,  in  size  from  a  split  pea  to  a  shilUng.  The  face,  scalp,  hands 
and  arms  may  show  these  vesicles  or  scabs,  and  the  condition 
is  very  prone  to  spread. 


SCHOOL  HYGIENE  58 1 

Favus. — In  this  condition,  which  is  of  rarer  occurrence,  orange- 
coloured  crusts  are  to  be  observed  on  the  scalp.  The  hair  is 
brittle  and  dull,  but  not  generally  broken  off  short;  and  there 
is  sometimes  a  mousy  odour  to  be  observed.  It  is  generally 
seen  in  children  of  poor  physique  and  low  nutrition,  and  ha?, 
not  much  tendency  to  spread.  The  treatment  is  very  similar 
to  that  of  ringworm. 

Scabies  or  Itch. — -In  this  complaint  papules,  pustules,  excoria- 
tions, and  fissures  may  be  seen,  more  especially  between  the 
fingers.  It  is  highly  contagious,  and  demands  prompt  medical 
treatment. 

The  Clothing  of  school  children  must  be  light  and  loose,  so 
that  it  does  not  interfere  with  any  natural  function  or  move- 
ment, and  it  should  be  suitably  distributed,  so  as  to  help  to 
regulate  the  body  temperature  and  to  guard  the  system  from 
chills. 

Some  common  and  easily  corrected  errors  in  the  clothing  of 
scholars  relate  to  articles  (such  as  tight  collars  or  neck-bands, 
garters,  stays,  bodices,  belts,  braces,  etc.)  which  by  their  pres- 
sure and  constriction  interfere  with  the  circulation  of  the 
blood,  the  function  of  important  organs,  or  free  muscular 
movements ;  or  which  by  their  weight  and  ill-fit  lead  to 
deformity  and  awkward  gait,  such  as  heavy,  ill-fitting  boots. 

Food  is  not  only  necessary  to  repair  the  wear  of  the  tissues 
and  to  furnish  heat  and  energy,  but  also  for  growth,  in  children. 

School  children  require  relatively  more  food  than  adults, 
because  the  food  has  to  provide  for  the  growth  and  the  greater 
energy  generally  manifested.  More  especially  is  an  abundance 
of  good  food  necessary  between  10  and  14  in  girls,  and  14  and  20 
in  boys. 

Children  of  the  ages  below  indicated  require  each  day  about 
the  following  amounts  of  water-free  food  constituents: 


Seven  V'ears. 

I'en  Years. 

Fourteen  Years. 

oz. 

oz. 

oz. 

Proteids 

2-0 

2-5 

3-0 

Fats 

2-3 

3-0 

3-5 

Carbo-hydrates 

8-0 

107 

127 

Mineral  matter 

07 

0-8 

0-8 

i3*o  17*0 


The  symptoms  of  insufficient  or  wrong  feeding  are:  Emacia- 
tion; deficient  and  flabby  muscles;  arrested  growth;  anaemia 
and  sallow  skin;  looseness  of  bowels;  lassitude,  inattention  and 


582  HYGIENE    AND    PUBLIC    HEALTH 

mental  dulness.  The  conditions  known  as  Rickets  or  Scurvy 
are  favoured  by  wrong  feeding. 

Tlie  Education  (Provision  of  Meals)  Act  of  1906  enables 
Education  Authorities  to  provide  meals  for  school  children,  and 
to  recover  the  cost  from  the  parent,  where  possible.  Where  this 
provision  is  made  at  the  schools,  the  teachers  often  assist  in  the 
cooking,  and  the  elder  girls  are  also  encouraged  to  do  so.  The 
elder  girls  thus  receive  some  of  the  instruction  in  simple  cooking 
which  is  so  necessary.  This  knowledge  should  be  supplemented 
at  continuation  classes. 

The  rules  for  the  diet  of  school  children  embrace  a  plain, 
wholesome,  generous,  nutritious,  digestible,  and  varied  fare,  in 
which  the  amount  of  fresh  meat  allowed  is  limited,  and  fresh 
fruit,  and  baked  and  stewed  fruit,  should  figure  prominently. 
Raw  apples  and  nuts,  in  addition  to  their  nutritive  value,  are 
specially  good  for  the  teeth,  more  particularly  at  the  end  of  a 
meal.  The  craving  for  sweet  things  should  be  met  by  supplying 
these  in  reasonable  quantity  at  the  end  of  a  meal,  after  the  appe- 
tite has  been  first  satisfied. 

Indigestion  may  arise  from: — Bad  teeth;  improper  mastica- 
tion; irregular  meals;  tough  and  improper  food;  too  frequent 
meals;  food  too  hot;  stewed  tea;  tight  belts,  stays,  etc. 

The  good  habits  to  be  cultivated  are: — Slow  eating  and  good 
chewing;  sufficient  but  not  excessive  food;  regular  meals; 
regular  evacuations ;  the  cleaning  of  the  teeth. 

Bad  teeth  may  cause: — Pain  and  loss  of  rest;  abscess  and  the 
swallowing  of  pus;  enlarged  glands  and  disfiguring  scars;  indiges- 
tion ;  foetid  breath ;  the  habits  of  eating  soft  food  and  imperfectly 
masticating  the  food;  grave  constitutional  conditions  due  to 
malnutrition.  An  abscess  in  connection  with  the  temporary 
teeth  may  affect  the  development  of  the  permanent  teeth,  and 
this  may  lead  to  imperfect  mastication  and  defective  articulation. 

Quite  85  per  cent,  of  scholars  give  evidence  of  some  degree  of 
dental  caries.  When  this  condition  is  extensive  the  physical 
measurements  are  generally  below  the  average.  A  tooth 
attacked  with  caries  tends  to  promote  the  spread  of  the  con- 
dition to  other  teeth.  The  preservation  of  the  teeth  is  most 
important,  and  the  conservative  treatment  should  commence 
before  8.  A  yearly  inspection  of  the  teeth  is  therefore  desirable, 
and  the  general  use  of  tooth-l')rushes  should  be  considered  an 
nsseiUial  act  of  cleanliness. 

The  value  of  Anthropometrical  Data  is  considerable.    Thej' 


SrHOOI.    HYGIENE  583 

enable  us  to  learn  whether  growth  is  occurring  at  an  exceptional 
rate  at  any  age,  and  thus  to  make  provision  for  the  fact  that 
the  powers  of  mental  and  physical  application  are  thereby 
reduced.  In  this  connection  it  is  important  to  note  that  excep- 
tional growth  is  most  liable  to  occur  at  or  about  puberty,  and  that 
growth  in  height  without  a  corresponding  increase  in  weight 
demands  attention. 

If  growth  is  found  to  be  deficient,  it  may  indicate  insufficient 
food  or  clothing,  an  excessive  expenditure  of  energy  in  mental 
work,  or  the  onset  of  some  disease. 

Good  nurture  promotes  growth,  and  hence  the  height  and 
weight  are  indications  of  nutrition.  It  is  for  this  reason  that 
children  of  the  better  classes  are  heavier  and  taller  in  both  sexes 
than  those  of  the  poorer  classes.  Dr.  Kerr  has  pointed  out  that 
dullards  are  generally  below  the  mean  height.  The  effects  of 
heredity  and  home  environment,  underfeeding,  neglect,  and  bad 
conditions  of  the  mother's  life  (before  and  after  birth)  are  very 
evident  in  the  anthropometrical  data  of  schools  in  the  very  poor 
districts  of  large  cities. 

The  only  anthropometrical  data  which  it  is  found  possible  to 
obtain  at  present  under  the  scheme  of  medical  inspection  of 
elementary  school  children,  relate  to  the  weight  and  height;  but 
in  many  private  schools  chest  measurements  are  also  taken  at  the 
level  of  the  nipple,  both  after  emptying  and  expanding  the  lungs. 
The  chief  aims  of  anthropometrical  observations  are  as  follows: 

1.  To  determine  averages  and  standard  deviations  at  different 
ages  and  for  both  sexes,  having  due  regard  to  racial  and  environ- 
mental differences. 

2.  To  correlate  mental  and  physical  growth,  with  a  view  to 
testing  the  efficiency  of  different  systems  of  education  and  of 
indicating  the  amount  of  work  that  may  advantageously  be 
attempted  at  different  ages,  thereby  minimizing  the  dangers  of 
overpressure  and  adapting  education  to  local  needs. 

3.  To  mark  out  the  physically  or  mentally  unfit  for  special 
educational  treatment. 

4.  Where  the  deviation  is  abnormal  in  a  mnnber  of  indi- 
viduals, a  whole  school,  or  a  whole  area,  it  would  point  to 
the  necessity  for  special  investigations  of  social  conditions  and 
environment. 

The  subjoined  table  shows  that: 

I.  Boys  are  heavier  than  girls  up  to  12,  but  soon  after  12  they 
lose  their  superiority  for  three  years,  regaining  it  by  i6. 


584 


HYGIENE  AND  PUBLIC  HEALTH 


2.  In  boys  the  greatest  increase  occurs  from  about  14  to  16, 
in  girls  from  about  12  to  15. 

3.  The  rate  of  growth  is  irregular  or  interrupted.  Boys  are 
taller  than  girls  up  to  12,  when  girls  pass  them,  and  retain  an 
advantage  to  nearly  15. 

4.  In  boys  the  greatest  annual  increases  are  from  5  to  6  (almost 
3  inches)  and  from  14  to  15  (about  3  inches) — viz.,  at  the  beginning 
and  the  end  of  elementary  school  education. 

5-  In  girls  the  greatest  annual  increase  is  about  12. 

6.  In  girls  the  annual  increase  is  more  uniform  than  in  boys 
up  to  14. 

7.  In  girls  growth  begins  to  slow  down  between  12  and  13, 
and  at  14I  girls  have  nearly  completed  their  growth,  while  boys 
grow  rapidly  up  to  19. 

8.  Girls  of  13  and  14  are  generally  taller  and  heavier  than  boys 
of  the  same  age. 

Anthropometrical  Measurements  (Anthropometrical  Committee  of 
THE  British  Association). 


Age. 

Average  Weight  (in  pounds). 

•Average  Height  (in  inch 

es). 

5 

Boys. 

Increase. 

Girls. 

Increase. 

Roys. 

1  ncrease. 

Girls. 

Increase. 

39-9 



39-2 



41-03 

_ 

40-55 



6 

44-4 

4-5 

41-7 

2-5 

44-00 

2-97 

42-88 

2-33 

7 

49-7 

5-3 

47-S 

5-8 

45-97 

1-97 

44-45 

1-57 

8 

54-9 

5-2 

52-1 

4-6 

47-05 

1-08 

46-60 

2-15 

9 

6o'4 

s-s 

5S-S 

3-4 

49-70 

2-65 

48-73 

2-13 

10 

67-S 

7-1 

62-0 

6-5 

51-84 

2-14 

51-05 

2-32 

II 

72-0 

4-5 

68-1 

6-1 

53-50 

1-66 

53-10 

2-05 

12 

76-7 

4.7 

76-4 

8.3 

54-99 

1-49 

55-66 

2-56 

13 

82-6 

5-9 

87-2 

IO-8 

56-91 

1-92 

57-77 

2-11 

14 

92-0 

9-4 

96-7 

9-5     ' 

59-33 

2-42 

59-80 

2-03 

IS 

I02'7 

IO-7 

106-3 

9-6 

62-24 

2-91 

60-93 

1-13 

16 

IIQ'O 

16.3 

II3-I 

6-8 

64-31 

2-07 

61-75 

0-82     , 

1 

In  addition  to  special  schools  for  the  blind,  deaf  and  dumb, 
epileptic,  and  definitel}'  feeble-minded  children,  some  provision 
has  been  made  during  the  past  few  years  for  the  partially  deaf, 
backward,  physically  defective,  delicate,  and  tuberculous  chil- 
dren, and  children  suffering  from  ophthalmia  and  ringworm. 
The  establishment  of  open-air  schools,  playground  classes,  and 
open-air  classrooms,  are  further  new  features  in  the  educational 
scheme.  But  apart  from  certain  classes  of  abnormal  children 
who  require  special  school  training,  there  are  many  whose  special 


SCHOOL   HYGIENE  585 

needs  can  be  met  by  an  adaptation  of  the  arrangements  that 
obtain  in  ordinary  pubhc  elementary  schools. 

Open-air  recovery  schools  are  of  value  more  especially  for 
children  suffering  from  anaemia,  incipient  (closed)  pulmonary 
tuberculosis,  struma  and  scrofula,  mental  dulness  and  backward- 
ness, and  heart  disease.  Simple  wooden  or  Doecker  buildings 
suffice  for  open-air  schools,  and  chairs  or  rugs  are  placed  on  the 
adjoining  grounds  both  for  class  purposes  and  to  enable  children 
to  rest  and  sleep  for  two  hours  after  the  early  dinner.  A  nurse 
is  in  constant  attendance;  and  great  benefits, physical  and  mental, 
are  derived  by  the  children.  Although  the  amount  of  formal 
teaching  does  not  usually  exceed  three  hours  per  day,  the  scholars 
are  generally  found  to  have  kept  their  places  on  return  to  school; 
and  improvements,  in  general  appearance  and  carriage,  in  nutri- 
tion (as  evidenced  by  weight),  an  increased  amount  of  hcemo- 
globin  in  the  blood,  and  an  improved  educational  response,  are 
generally  to  be  noted.  Something  is  also  being  done  to  supply 
the  need  for  open-air  residential  schools,  in  addition  to  open-air 
day-schools. 

The  State  has  the  right  to  intervene  and  protect  a  child  not 
only  against  an  employer,  but  also  against  its  parents.  That 
this  protection  is  needed  in  the  educational  interest  of  the  child, 
apart  from  other  considerations,  was  proved  by  an  inquiry  made 
some  years  ago,  when  it  was  estimated  that  50,000  children 
under  14  years  of  age  were  working  over  20  hours  a  week,  in 
addition  to  the  2yh  hours  at  school.  Under  such  a  strain  it  is 
certain  that  the  physical  health  and  development  of  young 
children  must  suffer,  and  the  insufficient  recreation  involved  in 
much  out-of-school  work  must  materially  reduce  the  educational 
response.  It  is,  therefore,  important  to  briefly  review  the  legal 
provisions  which  now  exist  for  limiting  the  amount  and  regulat- 
ing the  nature  of  the  out-of-school  work  which  an  elementary 
school-child  may  perform.  Under  the  Elementary  Education 
Acts,  1876,  1899,  a  child  under  10  years  of  age  may  not  be  em- 
ployed for  trade  or  gain,  nor  even  after  10  years  of  age,  unless 
certified  as  having  reached  the  prescribed  standard;  from  12 
years  of  age  the  child  may  be  partially  exempted  from  school 
attendance  on  certain  conditions. 

Under  the  Factories  and  Workshops  Act  of  1901  a  child  under 
12  years  of  age  may  not  be  employed  in  or  about  mines  or  fac- 
tories; children  under  14  years  of  age  are  more  or  less  protected 
as  to  hours  of  work,  overtime,   meal-times,  night  and  Sunday 


586  HYGIENE    AND    PUBLIC    HEALTH 

work,  and  dangerous  industries;  such  children  may  only  be  em 
ployed  for  half  days  or  alternate  days;  and,  further,  a  child  under 
i6  years  of  age  must  obtain  a  certificate  of  physical  fitness  before 
being  allowed  to  work  in  factories  (or,  maybe,  in  workshops). 
Under  the  Employment  of  Children  Act  of  1903  no  child  imder 
II  years  of  age  may  be  employed  in  street  trading,  and  the  local 
authority  may  prohibit  or  conditionally  permit  this  up  to  the 
age  of  16;  and  the  employment  of  a  child  under  14  may  be  pro- 
hibited below  a  certain  age,  beyond  or  between  certain  hours,  or 
in  specifie'd  dangerous  or  injurious  occupations,  if  so  ordered  by 
the  local  authority. 

3.  The  Spread  of  Infection  in  Schools. 

Among  the  means  of  spreading  infection  by  personal  communi- 
cation, compulsory  school  attendance  at  the  most  susceptible 
period  of  life  must  occupy  a  prominent  place.  At  the  present 
time  we  are  dependent  in  our  efforts  to  prevent  the  spread  of 
infection  in  schools  on  {a)  the  compulsory  information  supplied 
under  the  Infectious  Disease  Notification  Act,  and  (b)  on  the 
information  supplied  by  teachers  and  others,  as  to  measles, 
whooping-cough,  etc.,  in  the  districts  where  these  diseases  are 
not  compulsorily  notifiable.  It  is  now  usual  for  the  medical 
officer  of  health,  on  the  receipt  of  the  notification  of  a  case  of 
infectious  disease  in  the  person  of  a  child  attending  school,  to 
inform  the  school  authorities  of  the  case,  so  that  all  children  in 
the  same  house  attending  school  may  be  excluded  until  the 
premises  are  declared  free  from  infection.  If  the  child  attacked 
is  promptly  removed  to  an  isolation  hospital,  the  room,  clothes, 
and  bedding  can  be  at  once  disinfected,  and  the  other  children 
may  be  allowed  to  return  to  school  on  the  expiration  of  the 
number  of  days  corresponding  to  the  maximum  incubation 
period  of  the  disease  in  question.  If  the  child  attacked  is  kept 
at  home  during  its  illness,  the  other  children  in  the  house  must 
be  excluded  from  school  until  the  recovery  of  the  patient,  and 
the  disinfection  of  the  premises.  The  diseases  for  which  these 
precautions  are  especially  necessary  are  small-pox,  typhus, 
diphtheria,  and  scarlet  fever;  and  measles  and  whooping-cough 
also,  when  such  children  are  attending  the  infant  departments 
of  schools, 

The  medical  officer  of  health  has  power,  by  issuing  a  certifi- 
cate which  is  endorsed  by  the  local  sanitary  authority  or  any 
two  members  of  it,  to  close  a  school;  or  he  may  obtain  such 


SCHOOL    HYGIENE  587 

closure  by  getting  the  formal  approval  thereto  of  the  school 
medical  officer.  Owing  to  the  co-operation  of  the  school  officer 
and  the  officer  of  health  it  is  now  becoming  unusual  for  the 
medical  officer  of  health  to  take  such  action  through  the  sanitary 
authority ;  but  when  this  course  is  taken  he  must  at  once  certify 
to  the  school  medical  officer,  and  this  is  also  necessary  when  he 
excludes  children  from  school  attendance. 

It  is  safe  to  conclude  that,  excluding  the  infant  department, 
the  large  majority  of  children  attending  school  have  already 
suffered  from  measles;  but  in  this,  as  in  other  infectious  diseases, 
the  proportions  of  those  who  have  previously  suffered  will 
vary  in  different  schools,  and  in  different  classes;  and  it  is  a 
great  advantage  in  our  efforts  to  control  the  spread  of  infectious 
disease  to  be  able  to  refer  to  an  infectious-fever  history  of  the 
scholars  in  each  class.  In  the  case  of  measles  and  whooping- 
cough,  school  closure  rarely  proves  of  value;  good  results  have 
more  often  been  obtained  by  closing  a  classroom  on  the  ninth 
day  after  the  occurrence  of  the  first  case,  for  five  days ;  and  then 
readmitting  to  the  class  only  those  who  are  quite  free  from  any 
suspicious  symptoms.  A  similar  procedure  may  be  adopted 
in  reference  to  mumps,  chicken  -  pox,  and  whooping  -  cough. 
During  the  prevalence  of  measles  all  children  with  "  colds  " 
should  be  excluded  for  three  days,  and  the  same  rigid  exclusion 
of  all  those  who  might  conceivably  be  sickening  has  to  be  prac- 
tised during  the  prevalence  of  other  infectious  diseases.  In  those 
cases  where  it  seems  desirable  to  go  beyond  the  closure  of  a 
classroom  or  of  a  department  and  to  close  the  school,  neigh- 
bouring schools  should  be  included  in  special  circumstances,  and 
the  Sunday-schools  should  then  also  be  closed.  But  only  when 
there  is  imminent  risk  of  an  epidemic,  or  when  the  evidence  points 
to  a  school  or  class  as  a  source  of  infection,  should  class  or  school 
closure  be  resorted  to.  Certainly  school  closure  in  urban  dis- 
tricts never  offers  the  same  advantages  as  school  closure  in  rural 
districts,  because  in  the  former  case  the  children  mix  so  much 
out  of  school.  The  best  preventive  results  are  to  be  expected 
from  a  prompt  exclusion  of  all  suspects  and  carrier  cases  of 
infection;  and  as  school  teachers  become  better  informed  and 
more  skilled  in  detecting  suspicious  cases  of  early  infection, 
and  as  a  frequent  medical  inspection  of  scholars  during  the 
epidemic  prevalence  of  disease  is  more  generally  provided,  the 
occasions  on  which  school  closure  is  demanded  will  become  few 
and  far  between.     In   this  connection  it  is  only  necessary  to 


588  HYGIENE    AND   PUBLIC   HEALTH 

allude  to  the  significance  of  brief  absences  of  scholars,  when  in- 
fectious disease  is  prevalent  in  the  district,  and  the  dangers  of 
then  attempting  to  maintain  high  average  attendances. 

Whenever  a  sufferer,  a  contact,  or  a  suspect,  is  excluded  from 
school,  it  is  important  that  a  knowledge  of  this  fact  should  be 
shared  by  the  school  medical  officer,  the  medical  officer  of  health, 
and  the  head-teacher  of  the  school ;  and  that  preventive  measures 
should  include  such  inter-notification  as  will  secure  this  end. 
Moreover,  the  school- attendance  officer  should  notify  any  such 
cases  not  already  known  to  the  school  medical  officer,  the  medical 
officer  of  health,  and  the  head-teacher.  It  may  also  be  neces- 
sary to  obtain  the  closure  of  elementary  schools  for  defective 
sanitary  arrangements,  which  appear  to  have  some  connection 
with  illness  (such  as  enteric  fever,  diarrhoea,  or  diphtheria) 
occurring  amongst  the  scholars. 

To  enable  a  decision  to  be  arrived  at  as  to  what  extra  measures 
are  called  for,  in  order  to  reduce  the  spread  of  infection  at  schools, 
it  is  necessary  to  appreciate  the  fact  that  a  larger  part  of  the 
spread  results  from  undiagnosed  mild  cases  of  infection  than 
from  children  resuming  school  attendance  too  soon  after  the 
disease  has  been  diagnosed  and  treated.  The  measure  which 
has  met  with  most  favour  is  to  submit  the  scholars  to  repeated 
medical  inspections  during  the  exceptional  prevalence  of  infec- 
tious disease,  and  to  exclude  all  suspects  from  school  attendance. 
A  good  knowledge  of  the  early  symptoms  of  communicable 
diseases  enables  teachers  to  take  similar  action  day  b}^  day.  It 
is  most  important  that  greater  efforts  should  be  made  to  promote 
this  knowledge  among  school  teachers.  In  all  schools  a  medical 
man  or  woman  should  in  non-epidemic  times  examine  the 
scholars  occasionally,  with  the  view  of  detecting  those  numerous 
conditions  which  unfit  a  scholar  temporarily  for  school  attend- 
ance, or  which  require  early  correction,  such  as  developmental 
defects,  faulty  vision,  overpressure,  and  diseased  conditions  not 
necessarily  infectious.  He  should  also  be  able  to  make  a  prompt 
examination  of  every  pupil  referred  to  him  at  any  time  by  a 
teacher,  and  should  lecture  to  and  instruct  the  teachers  upon  the 
symptoms  of  disease  in  school  life.  All  suspicious  cases  should  be 
excluded  from  school,  and  after  diagnosis  should  be  handed  over 
to  the  care  of  their  regular  medical  attendant,  when  such  exists. 

The  common  symptoms  of  fever  are: — Irritability,  peevish- 
ness and  drowsiness;  nausea  and  vomiting;  shivering  fits;  head- 
ache; loss  of  appetite,  coated  tongue  and  thirst;  frequent  pulse 


SCHOOL   HYGIENE  589 

and  respirations;  hot,  dry  skin  or  sweating;  temperature  above 
100°  F. 

The  chief  special  symptoms  of  the  infectious  fevers  are: — 

Diphtheria. — Extreme  prostration;  sore  throat,  with  dirty 
white  patches  on  tonsils;  often  noisy  breathing  and  hoarseness, 
swelling  of  glands  at  angles  of  lower  jaw  and  nasal  discharge 
("  Nasal  Diphtheria  ").     No  rash. 

Scarlet  Fever  or  Scarlatina. — Sore  throat;  vomiting;  "  straw- 
berry tongue  ";  bright  red  rash,  first  on  neck  and  upper  chest, 
and  then  spreading  over  body;  later  a  branny  peeling  of  skin. 
May  be  discharge  from  ear. 

Measles. — Symptoms  of  a  bad  "  cold  in  the  head  ";  then  after 
three  days  a  blotchy  dusky-red  rash  appears  on  face  and  hands, 
soon  spreading  over  body;  often  a  hard  cough;  sometimes  sore 
throat. 

German  Measles. — A  rash,  somewhat  similar  to  Measles,  but 
preceded  by  sore  throat  instead  of  cold  in  head. 

Whooping-Cough.—-A  week  or  two  of  ordinary  cough  and  then 
a  series  of  short  violent  expiratory  coughs,  followed  by  a  long 
crowing  inspiration  ("  whoop  "),  which  may  be  followed  by 
vomiting  or  nose-bleeding. 

Mumps. — Painful  swellings  at  sides  of  the  neck,  in  front  and 
below  ear;  sometimes  only  on  one  side. 

Enteric  or  Typhoid  Fever. — Frontal  headache;  pains  in  limbs; 
nausea  and  vomiting;  prostration;  generally  diarrhoea.  A  few 
small  pink  spots,  chiefly  on  abdomen,  after  the  tenth  day  of  illness. 

Small-Pox. — Sickness,  backache  and  considerable  illness  for  a 
day  or  two;  then  pimples  appear,  first  on  face,  which  become 
watery  blebs  in  3  days  and  crusts  in  another  few  days. 

Chicken-Pox. — Mild  fever.  Scattered  pimples,  first  on  body 
and  fewest  on  face;  rapidly  becoming  watery  blisters.  Crusts 
in  4  or  5  days. 

N.B. — If  child  has  been  vaccinated  Small-pox  is  generally 
very  mild  and  resembles  Chicken-pox. 

Typhus. — Marked  fever;  great  nervous  disturbance  (prostra- 
tion, depression,  etc.).  Mulberry- hued  spots  and  motthng  of 
skin  in  parts — chiefly  over  stomach  and  on  chest. 

Influenza. — Shivering  attacks;  sneezing;  running  of  eyes  and 
nose;  pains  in  limbs;  great  prostration;  often  cough. 

Epidemic  Cerebrospinal  Fever. — Intense  headache;  persistent 
vomiting;  stiffness  and  retraction  of  neck;  pain  down  spine; 
drowsiness;  varied  rashes. 


590  HYGIENE    AND    PUBLIC   HEALTH 

Tuberculosis  of  Lungs  (Consumption). — Lassitude;  loss  of 
strength;  wasting;  cough  and  shortness  of  breath.  The  preva- 
lence of  this  disease  among  school  children  varies  somewhat  in 
different  districts.  It  probably  does  not  exceed  i  per  cent.,  on 
the  average,  in  England  and  Wales;  but  the  disease  is  more 
prevalent  among  the  teachers. 

The  danger  of  infection  is  not  necessarily  proportional  to  the 
severity  of  the  attack. 

"  A  sudden  cold  in  the  nose  or  throat,  a  hot  face,  unnaturally 
bright  eyes,  a  rash,  a  swollen  neck,  a  cough  ending  in  the  charac- 
teristic whoop,  a  fit  of  sickness  or  shivering,  a  day  or  two  of  un- 
usual irritability,  are  all  signs  which  no  one  can  afford  to  neglect." 
— -Board  of  Education. 

The  circumstances  favouring  the  spread  of  infectious  diseases 
at  school  are: 

Mild  and  unrecognized  cases;  "  carrier  "  cases;  and  those 
incubating  and  in  early  stages  of  infectious  diseases  (especially 
Measles  and  Whooping-Cough).  The  close  personal  contact  of 
scholars  in  classrooms  and  at  play.  The  favourable  ages  of 
the  scholars.  The  too  hasty  return  to  school  of  sick  children 
and  "  contacts."  The  favouring  circumstances  of  cloakrooms, 
and  of  school  books,  etc.,  used  in  common. 

The  special  precautions  when  an  epidemic  threatens  or  is 
established,  are: — 

Inspection  of  Scholars.  Cleansing  and  Disinfection.  The 
exclusion  of  children  with  possible  Fever  symptoms,  such  as — 

If  Diphtheria. — Those  with  sore  throat,  enlarged  glands  in  neck 
or  nasal  discharge. 

If  Scarlet  Fever  or  German  Measles. — Those  with  sore  throat. 

//  Measles  or  Influenza.- — Those  with  severe  "  cold,"  with 
sneezing,  redness  of  eyes  and  running  of  nose. 

//  Whooping-Cough. — ^Those  with  a  violent  cough. 

//  Small-Pox. — Those  with  headache,  vomiting  and  pain  in 
back. 

If  Enteric  Fever. — Those  with  diarrhoea  and  abdominal  dis- 
comfort or  pain. 

If  Mumps. — Those  with  a  swelling  in  front  of  or  below  ears. 

The  Education  (Administrative  Provisions)  Act  of  1907  re- 
quires the  Medical  Inspection  of  all  elementary  school  children 
at  the  period  of  commencing  school  attendance,  and  on  such 
other  occasions  as  the  Board  of  Education  may  direct,  and  gives 
the  local  Education  Authority  power  to  make  such  arrangements 


SCHOOL   HYGIENE  59I 

in  the  lu-altli-intcrcsts  uf  the  child  as  the  Board  of  Education 
may  sanction. 

Since  the  passing  of  this  Act  the  Board  of  Education  has 
issued  several  circulars  upon  the  subject  of  the  medical  inspec- 
tion of  children  in  public  elementary  schools.  In  the  circular 
issued  November,  1907,  stress  is  laid  upon  the  fact  that  school 
hygiene  cannot  be  divorced  from  home  hygiene,  and  that,  gener- 
ally speaking,  the  work  of  the  inspection  should  be  supervised  by 
the  medical  officer  of  health  of  the  authority  which  appoints  the 
Education  Committee.  In  appointing  assistants  for  this  work, 
it  is  suggested  that  preference  should  be  given  to  medical  men 
and  women  who  have  been  trained  in  State  medicine  or  hold  the 
Diploma  in  Public  Health,  who  have  had  some  definite  experience 
of  school  hygiene,  and  special  opportimities  for  the  study  of  dis- 
eases in  children ;  the  teacher,  the  school  nurse  (where  such  exists), 
and  the  parents  or  guardians  of  the  child  must  heartily  co-operate 
with  the  school  medical  officer;  the  character  and  degree  of 
medical  inspection  is  to  embrace  medical  examination  and  super- 
vision, not  only  of  children  known  to  be  weakly  or  ailing,  but  of 
all  children  of  the  elementary  schools,  with  a  view  to  adapting 
and  modifying  the  system  of  education  to  the  needs  and  capacities 
of  the  child,  procuring  the  early  detection  of  unsuspected  defects, 
checking  incipient  maladies  at  their  onset,  and  furnishing  the 
facts  which  will  guide  educational  authorities  in  relation  to  the 
physical  and  mental  development  of  the  school  child.  Tlie 
Board  maintains  that  not  less  than  three  inspections  during  the 
school  life  of  the  child  will  be  necessary  to  secure  the  results 
desired — namely,  the  first  at  the  time  of  admission  to  school; 
the  second  at  or  about  the  third  year  of  school  attendance;  and 
the  third  at  or  about  the  sixth  year.  A  further  inspection  im- 
mediately before  the  departure  of  the  child  into  working  life  is 
also  advocated.  It  is  required  that  the  inspections  should  be 
made  in  school  hours  and  on  school  premises ;  and  that  the  facts 
revealed  by  inspection  must  be  entered  in  a  register  kept  at 
the  school,  a  copy  of  the  entries  being  transmitted  to  any  other 
school  to  which  the  child  may  go.  Every  school  medical  ofiticer 
must  report  annually  to  the  Local  Education  Authority,  and 
send  two  copies  of  the  report  to  the  Board  of  Education;  the 
report  to  deal  with  the  calendar  year.  Local  Education  Author- 
ities are  to  make  arrangements  without  delay  for  obtaining 
amelioration  of  the  evils  revealed  by  medical  inspection. 

In  a  circular  issued  in  August,  1908,  the  Board  of  Education 


592  HYGIENE    AND   PUBLIC    HEALTH 

draws  attention  to  the  fact  that  the  school  medical  officer  of  the 
Local  Education  Authority  is  for  the  first  time  recognized  in  the 
Education  Code  of  1908,  as  an  officer  having  specific  functions, 
as  follows: 

1.  Those  of  reporting  on  the  working  and  effect  of  any  arrange- 
ments made  under  Article  44  for  educating  children  at  open-air 
schools  or  other  places  selected  with  the  view  to  the  improve- 
ment of  the  health  and  physical  condition  of  the  children. 

2.  The  power  of  advising  or  approving  the  closure  of  the  school 
on  account  of  infectious  disease. 

3.  The  power  of  authorizing  the  exclusion  of  certain  children 
from  school  on  the  grounds  that  such  exclusion  may  prevent  the 
spread  of  infectious  disease. 

The  New  Code  also  makes  it  a  condition  of  grant  that  satisfac- 
tory provision  for  the  medical  inspection  of  children  shall  be 
made.  In  this  circular  it  is  further  pointed  out  that  where 
medical  inspection  reveals  defects,  the  first  step  should  be  to 
notify  parents,  and  to  urge  the  desirability  of  obtaining  treat- 
ment by  medical  practitioners;  that  a  school  nurse  is  useful  in 
assisting  in  the  work  of  medical  inspection,  and  in  applying,  or 
showing  the  parents  how  to  apply,  remedies  for  minor  ailments; 
that  after  efforts  to  obtain  the  provision  of  spectacles  by  the 
child's  parents  or  by  any  voluntary  associations  have  failed,  the 
Board  will  consider  proposals  for  a  Local  Education  Authority 
to  provide  these  free  of  charge;  that  before  direct  treatment 
of  ailments  is  undertaken  by  the  Local  Education  Authority, 
whether  by  means  of  a  school  clinic  or  by  themselves  supplying 
and  paying  for  medical  treatment,  full  advantage  should  be  taken 
of  the  benefits  of  such  institutions  as  hospitals,  dispensaries,  etc., 
to  the  funds  of  which  they  are  empowered  to  make  a  contribution. 
School  clinics  are  either  Inspection  Clinics,  where  certain  of  the 
children  found  to  be  defectiveat  the  ordinaryinspectionsare  further 
examined,  or  Treatment  Clinics,  more  especially  for  the  treatment 
of  eye,  ear,  and  throat  troubles,  dental  caries,  and  ringworm. 

To  whatever  extent  medical  inspection  may  lead  to  the  detec- 
tion and  alleviation  of  physical  defects  in  school  children,  to  a 
corresponding  extent  will  children  gain  in  general  health  and 
development;  better  results  will  be  obtained  from  the  teaching 
at  school;  the  more  healthy  and  physically  fit  child  will  be  less 
a  drag  upon  the  resources  of  the  family;  and  the  State  and  pos- 
terity will  benefit  from  a  healthier  stock. 

Dr.   Thresh    compiled    the    following    statistical    table  (1909), 


SCHOOL  HYGIENE 


593 


from  the  results  of  the  medical  inspection  of  over  40,000  children 
in  certain  counties  and  towns  in  England  during  1908  and  1909 : 


Reported  to  be  suffering  from— 

- 

Apparent  Average 
Percentage. 

Uncleanly  head  and  body  .         .         .         .          i8-o 

Enlarged  tonsils 

13-0 

Defective  vision 

13-0 

Defective  nutrition 

8-0 

Adenoids    . 

8-0 

Badly  decayed  teeth 

8-0 

Eye  disease 

3-0 

Bodily  deformity 

2-4 

Skin  disease 

1-9 

External  ear  disease 

1-8 

Heart  disease 

1-5 

Lung  affections  . 

1-4 

Mentally  defective 

1-3 

Tuberculous  disease 

0-8 

Summary  of  Regulations  (London  County  Council)  with  Regard 
TO  THE  Exclusion  of  Children  from  School  on  Account  of 
Infectious  Diseases. 


Disease. 


Small-pox. 
Cholera. 


Diphtheria. 

Membranous 

Croup. 


Scarlet  Fever 
or  Scarla- 
tina. 


Erysipelas. 
Typhoid 

Fever  or 
Enteric  Fever. 


Measles. 


Exclusion  of  Children  suflFerinc 
from  the  Disease. 


(i)  Until  the  medical  at- 
tendant certifies,  if  the 
case  is  treated  at  home. 

(2)  Until  after  discharge 
from  hospital. 

( 1 )  If  the  case  is  treated  at 
home,  until  a  medical 
certificate,  based  upon 
bacteriological  exami- 
nation, is  furnished. 

(2)  Until  a  fortnight  after 
date  of  discharge  from 
hospital. 

(i)  Until  the  medical  at- 
tendant certifies,  if  the 
case  is  treated  at  home. 

(2)  Until  a  fortnight  after 
date  of  discharge  from 
hospital. 

(i)  Until  the  medical  at- 
tendant certifies,  if  the 
case  is  treated  at  home. 

{2)  Until  after  discharge 
from  hospital. 

At  least  one  month. 


Exclusion  ot  Children  living  in 
Houses  where  the  Disease  exists. 


Until  7  days  shall  have 
elapsed  after  the  date  of 
the  certificate  from  the 
Medical  Officer  of  Health 
that  the  house  is  free 
from  infection.  In  the 
event  of  the  head-tea- 
cher not  receiving  the 
certificate  that  the  pre- 
mises are  free  from  in- 
fection, it  becomes  his 
duty  to  send  to  the 
offices  of  the  local  Sani- 
tary Authority,  in  order 
that  he  may  procure  it. 


Not  to  be  excluded.  No 
proceedings  to  be  taken 
to  enforce  attendance  if 
Medical  Officer  of  Health 
specifically  orders  ex- 
clusion. 

Infants. — -All  infants  to  be 
excluded,  until  Monday 
following  14  days  from 
occurrence  of  last  case. 

3^ 


594 


HYGIENE    AND    PUBLIC   HEALTH 


Summary  of  Regulations  (London  County  Council)  with  Regard 
TO  THE  Exclusion  of  Children  from  School  on  Account  of 
Infectious  Diseases.— Continued. 


Disease. 

Exclusion  of  Children  .suffering 
from  the  Disease. 

Exelusion  of  Children  living  in 
Houses  wliere  the  Disease  exists. 

Measles. 

At  least  one  month. 

Seniors. — If  child  has  had 
the  disease,   not  to  be 
excluded.     If  child  has 
not  had  the  disease,  ex- 
clude until  Monday  fol- 
lowing    14    days    from 
occurrence  of  first  case. 

Mumps. 

One  month. 

Infants. — All  infants  to  be 
excluded  for  such  time 
as     medical     attendant 
considers  necessary.     If 
no    medical    attendant, 
for  three  weeks. 

Seniors. — If  child  has  had 
the  disease,  not  to  be 
excluded.     If  child  has 
not  had  the  disease,  ex- 
clude    for     the     same 
period  as  infants. 

Whooping- 
cough. 

As  long  as  the  cough  con- 
tinues,  but  not  to  be 

Infants. — -AH  infants  to  be 
excluded  two  weeks. 

readmitted      until     at 

Seniors. — If  child  has  had 

least  5  weeks  from  the 

the  disease,   not  to  be 

commencement     of 

excluded.     If  child  has 

whooping. 

not  had  the  disease,  ex- 
clude for  two  weeks. 

Chicken-pox. 

Two     weeks,      or     until 

Infants. — All  infants  to  be 

every  scab  is  off  scalp 
or  body. 

excluded  two  weeks. 
Seniors.- — If  child  has  had 
the  disease,   not  to  be 
excluded.      If  child  has 
not  had  the  disease,  ex- 
clude for  two  weeks. 

Ringworm, 

Until  medical  certificate 

Not  to  be  excluded. 

Favus. 

is    obtained    that    the 

Ophthalmia 

child  is  cured.     Wher- 

(Blight). 

ever  certificates  are  not 

Trachoma. 

readily    procurable, 

Scabies  (Itch). 

teachers     to     exercise 
their   discretion   as   to 
readmission,  and,  if  in 
doubt,    to    ask    school 
nurse. 

Consumption. 

Exclude  if  the  disease  is 

Ditto. 

accompanied  by  cough 
ing  or  spitting. 

• 

Note. — If  a  medical  attendant  or  the  Medical  Officer  of  Health  should 
certify,  in  any  special  case,  that  the  above  periods  of  exclusion  should  be 
extended,  teachers  are  to  observe  such  instructions,  and  to  at  once  com- 
municate with  the  Medical  Officer  (Education). 


SCHOOL   HYGIENE 


595 


SCHEDULE  OF  MEDICAL  INSPECTION  ISSUED  BY  THE 
BOARD  OF  EDUCATION. 

Schedule  of  Medical  Inspection. 

I. — Name Date  of  birth^ 

Address School 

II. — ^Personal  History: 

(a)  Previous  illnesses  of  child  (before  admission). 


Measles. 

Whooping- 
cough. 

Chicken-         Scarlet 
pox.              Fever. 

Diph- 
theria. 

Other 
Illnesses. - 

{b)  Family  medical  history  (if  exceptional).^ 


I.   Date  of  inspection     .... 

I. 

II.     1 

in.   ! 

1 

IV. 

1 

2.  Standard    and    regularity  of    atten- 

dance* ...... 

3.   Age  of  child -■      ..... 

4.  Clothing  and  footgear" 

III. — General  Conditions. 

5.  Height' 

6.  Weight*     ...... 

7.   Nutrition^           ..... 

8.  Cleanliness  and  condition  of  skin'"    . 

Head 

Body 

IV. —  Special  Conditions. 

1 

Q.  Teeth  1       .....          . 

10.  Nose  and  throat'-      .... 

Tonsils 

Adenoids        ..... 

! 

Submaxillary  and  cervical  glands  . 

II.   External  eye  disease'-* 

12.  Vision'*      ...... 

R. 

L. 

13.   Ear  disease  ^      ..... 

14.  Hearing  "            ..... 

1 5.   Speech '^               .          .          . 

16.  I\Iental  condition'*     .... 

\  — Disease  or  Dejonnitv.  ^ 

17.   Heart  and  circulation'-" 

18.  Lungs"'      ...... 

19.  Nervous  system-'-'       .... 

20.  Tuberculosis  •*    . 

21.   Rickets' 

22.  Deformities,  spinal  disease,  etc.-^ 

23.   Infectious  or  contagious  disease  " 

24.  Other  disease  or  defect-'   . 

Medical  officer's  initials 

1 

General  Observations. 
Directions  to  Parent  or  Teacher. 


596  HYGIENE    AND    PUBLIC    HEALTH 

RcfcTcficc 

Number  NoTES    FOR    INSPECTING    OFFICER. 

of  Note. 

1  Date  of  birth  to  be  stated  exactly,  date  of  month  and  year. 

2  "  Other  illnesses  "  should  include  any  other  serious  disorder  which 
must  be  taken  into  account  as  affecting,  directly  or  indirectly,  the  health 
of  the  child  in  after-life  —  e.g.,  rheumatism,  tuberculosis,  congenital 
syphilis,  small-pox,  enteric  fever,  meningitis,  mumps,  fits,  etc.  The  effects 
of  these,  if  still  traceable,  should  be  recorded. 

2  State  if  any  cases  of,  or  deaths  from,  phthisis,  etc.,  in  family. 

*  Note  backwardness. 

^  Age  to  be  stated  in  years  and  months,  thus,  5^*.t. 

^  Insufficiency,  need  of  repair,  and  uncleanliness  should  be  recorded 
(good,  average,  bad). 

'  Without  boots,  standing  erect  with  feet  together,  and  the  weight 
thrown  on  heels,  and  not  on  toes,  or  outside  of  feet. 

^  Without  boots,  otherwise  ordinary  indoor  clothes. 

Height  and  weight  may  be  recorded  in  English  measures,  if  preferred. 
In  annual  report,  however,  the  final  averages  should  be  recorded  in  both 
English  and  metric  measures. 

^  General  nutrition  as  distinct  from  muscular  development  or  physique 
as  such.  State  whether  good,  normal,  below  normal,  or  bad.  Under- 
nourishment is  the  point  to  determine.  Appearance  of  skin  and  hair, 
expression,  and  redness  or  pallor  of  mucous  membrane,  are  among  the 
indications. 

^^  Cleanliness  may  be  stated  generally  as  clean,  somewhat  dirty,  dirty. 
It  must  be  judged  for  head  and  body  separatel)'.  The  skin  of  the  body 
should  be  examined  for  cleanliness,  vermin,  etc.;  and  the  hair  for  scurf, 
nits,  vermin,  or  sores.  At  the  same  time  ringworm  and  other  skin  diseases 
should  be  looked  for. 

11  General  condition  and  cleanliness  of  temporary  and  permanent  teeth 
and  amount  of  decay.  Exceptional  features,  such  as  Hutchinsonian  teeth, 
should  be  noted.     Oral  sepsis. 

1-  The  presence  or  absence  of  obstruction  in  the  naso-pharynx  is  the  chief 
point  to  note.  Observation  shoiild  include  mouth-breathing;  inflamma- 
tion, enlargement,  or  suppuration  of  tonsils;  probable  or  obvious  presence 
of  adenoids,  polypi ;  specific  or  other  nasal  discharge,  catarrh,  malformation 
(palate),  etc. 

13  Including  blepharitis,  conjunctivitis,  diseases  of  cornea  and  lens, 
muscular  defects  (squints,  nystagmus,  twitchings),  etc. 

1*  To  be  tested  by  Snellen's  test  types  at  20  feet  distance  (=  6  metres). 

Result  to  be  recorded  in  the  usual  way — e.g.,  normal  V.=  -.     Examination 

of  each  eye  (R.  and  L.)  should  as  a  rule  be  undertaken  separately.     If 

the  V.  be  worse  than     ,  or  if  there  be  signs  of  eyestrain  or  headache,  fuller 

9 
examination  should  be  made  subsequently.     Omit  vision  testing  of  children 
under  six  years  of  age. 

1^  Including  suppuration,  obstruction,  etc. 

1^  If  hearing  be  abnormal,  or  such  as  interferes  with  class-work,  subse- 
quent examination  of  each  ear  should  be  undertaken  separately.  Apply 
tests  only  in  a  general  way  in  case  of  children  under  six  years  of  age. 

'■^  Including  defects  of  articulation,  lisping,  stammering,  etc. 

'^  Including  attention,  response,  signs  of  overstrain,  etc. 

The  general  intelligence  may  be  recorded  under  the  following  heads: 
(a)  Bright,  fair,  dull,  backward;  (b)  mentally  defective;  (c)  imbecile. 
Omit  testing  mental  capacity  of  children  under  six  years  of  age. 

'"  Under  the  following  headings  should  be  inserted  particulars  of  diseased 


SCHOOL   HYGIENE  597 

conditions  actually  present  or  signs  of  incipient  disease.  The  extent  of 
this  part  of  the  inspection  will  largely  depend  upon  the  findings  under 
previous  headings. 

-°  Include  heart-sounds,  position  of  apex-beat,  aninmia,  etc.,  in  case  of 
anything  abnormal  or  requiring  modification  of  school  conditions  or 
exercises. 

-I  Including  physical  and  clinical  signs  and  symptoms. 

--  Including  chorea,  epilepsy,  paralysis,  and  nervous  strains  and 
disorders. 

-•'  Glandular,  osseous,  pulmonary,  or  other  forms. 

-*  State  particular  form,  especially  in  younger  children. 

25  Including  defects  and  deformities  of  head,  trunk,  limbs.  Spinal 
curvature,  bone  disease,  deformed  chest,  shortened  limbs,  etc. 

28  Including  any  present  infectious,  parasitical,  or  contagious  disease, 
or  any  sequelae  existing.  At  each  inspection  the  occurrence  of  any  such 
diseases  since  last  inspection  should  be  noted. 

-"^  Any  weakness,  defect,  or  disease  not  included  above — e.g.,  ruptures — 
specially  unfitting  the  child  for  ordinary  school  life  or  physical  drill,  or 
requiring  either  exemption  from  special  branches  of  instruction,  or  par- 
ticular supervision. 


CHAPTER  XI 

DISINFECTION 

As  already  mentioned,  the  virus  of  a  contagious  disease  under- 
goes enormous  multiplication  in  the  body  of  the  sick  person,  and 
is  cast  off  during  the  period  of  illness  in  the  mucous  discharges 
and  secretions,  in  the  breath,  and  from  the  skin.  The  contagion 
infects  the  air  around  the  patient,  and  infects  the  bedding,  clothes, 
and  furniture  of  the  sick-room.  Disinfection  aims  at  the  destruc- 
tion of  the  virus  in  these  various  situations. 

In  the  first  place,  it  would  be  natural  to  suppose  that  the 
infective  particles  might  be  destroyed  before  leaving  the  body,  or 
as  soon  as  they  are  carried  into  the  air;  but  chemical  reagents 
strong  enough  to  destroy  specific  micro-organisms  would  cause 
injury  when  taken  into  the  system  or  when  diffused  into  the  air 
around  the  patient.  Where  the  virus  is  only  contained  in  the 
evacuations,  as  in  enteric  fever,  these  can  be  at  once  disinfected 
by  chemical  solutions;  but  in  the  case  of  the  other  common 
infectious  maladies  complete  disinfection  of  a  room  and  its 
contents  is  only  possible  when  the  patient  is  convalescent  and 
no  longer  a  source  of  infection  himself. 

No  agent  can  be  regarded  as  a  disinfectant  unless  it  is  capable 
of  destroying  the  organisms  with  which  it  is  brought  into  contact ; 
agents  which  merely  inhibit  bacterial  growth  and  prevent  de- 
composition are  known  as  antiseptics ;  while  others,  such  as 
charcoal,  which  oxidize  or  absorb  odorous  products,  are  termed 
deodorants.  Liquid  disinfectant  preparations  are  preferable  to 
solid,  for  they  can  be  much  more  efficiently  distributed;  and 
until  a  solid  disinfectant  is  in  solution,  it  is  powerless  to  act 
directly  upon  organisms.  The  final  results  attained  in  disinfec- 
tion are  greatly  influenced  by  the  nature  of  the  material  to  be 
disinfected.  Infectious  organisms  are  always  in  association  with 
a  greater  or  less  amount  of  other  organic  matter  under  natural 
conditions;  and  the  practical  question  which  has  to  be  cuiswered 

598 


DISINFECTION  599 

is: — What  is  the  required  strength  of  any  disinfecting  agent  to 
ensure  destruction  of  a  given  infection  in  its  natural  environment  ? 
Since  disinfectants  are  intended  for  the  destruction  of  the 
germs  of  specific  diseases,  it  has  long  been  recognized  that  the 
only  satisfactory  method  of  judging  their  relative  values  is  by 
ascertaining  the  actual  strengths  at  which  they  must  be  employed 
in  order  to  kill  these  germs  under  certain  tixed  conditions.  It 
is  true  that  bacteriologists  have  already  determined  the  action 
of  many  disinfectants  on  a  variety  of  micro-organisms,  but  owing 
to  the  employment  by  different  observers  of  different  methods, 
different  organisms,  and  different  standards  of  comparison,  the 
discrepancy  as  to  the  relative  value  of  disinfectants,  that  may  be 
found  in  the  literature  on  the  subject,  is  most  perplexing.  What 
is  wanted  is  a  standard  method  of  comparison  that  shall  be  both 
scientific  and  easily  practicable,  in  which  the  various  agents 
are  tested  side  by  side  under  precisely  similar  conditions.  With 
this  object  Rideal  and  W^alker  have  proposed  that  phenol  should 
be  taken  as  the  standard  disinfectant,  and  Bacillus  typhosus 
as  the  standard  germ  in  such  tests.  The  suggested  method  of 
working  is  as  follows: — To  5  c.c.  of  a  particular  dilution  of  the 
disinfectant  in  sterilized  water  are  added  5  drops  of  a  24  hour 
blood-heat  culture  of  Bacillus  typhosus  in  broth;  after  thorough 
admixture,  sub-cultures  are  taken  every  2|  minutes  up  to  15 
minutes,  and  these  are  incubated  for  at  least  48  hours  at  38°  C. 
The  temperature  during  medication  should  be  from  15°  to  18°  C, 
and  the  standard  broth  employed  should  have  a  reaction  of 
+ 15.  The  strength  or  efficiency  of  the  disinfectant  can  then  be 
expressed  in  multiples  of  carbolic  acid,  as  follows: — a  dilution 
of  the  disinfectant  being  obtained  which  does  the  same  work 
as  the  standard  carbolic  acid  dilution,  the  former  is  divided  by 
the  latter,  and  thus  a  ratio  is  obtained  which  is  called  the 
"  carbolic  acid  coefficient."  The  method  is  useful  as  one  upon 
which  it  may  be  found  possible  to  base  a  practical  test;  but 
it  does  not  tell  us  of  the  strength  at  which  the  various  disinfec- 
tants must  be  employed  in  actual  practice,  because  it  does  not 
take  into  account  the  influence  of  the  associated  organic  matter 
upon  the  potentialities  of  the  disinfectant.  In  other  words,  we 
have  not  in  practice  to  disinfect  the  typhoid  organism  in  a  broth 
culture,  but  the  organism  implanted  in  faeces  and  urine,  and 
often  more  or  less  protected  from  chemical  disinfectants  by 
surrounding  organic  matter. 


600  HYGIENE   AND   PUBLIC   HEALTH 

In  the  Martin-Chick  (Lister  Institute)  test  for  the  standardiza- 
tion of  disinfectants  for  practical  purposes,  the  temperature  for 
medication  is  fixed  at  20°  C,  an  interval  of  15  minutes  is 
allowed  for  the  disinfectant  to  act  on  the  test  organism  {Bacillus 
typhosus),  and  the  germicidal  value  is  not  determined  upon  the 
naked  organism  in  broth  culture,  but  an  emulsion  is  made  con- 
taining 3  per  cent,  of  human  faeces,  dried  at  102°  C,  and  subse- 
quently sterilized  by  steam  at  120°  C,  to  which  the  test  organism 
is  added.  The  results  obtained  by  the  Martin-Chick  test  indi- 
cate "  phenol  coefficients,"  which  are  very  much  less  than  those 
obtained  by  the  "  drop  "  method  of  Rideal  and  Walker.  From 
this  it  would  appear  that  the  germicidal  properties  of  many 
disinfectants  of  the  coal  tar  series  are  very  much  reduced  when 
the  test  organism  is  surrounded  or  protected  by  organic  matter 
of  the  nature  of  human  faeces. 

A  modification  of  the  Rideal-Walker  "  drop  "  method  has 
been  suggested  {The  Lancet,  November  20,  1909),  in  which 
Bacillus  coli  communis  is  advocated  as  the  test  organism,  instead 
of  Bacillus  typhosus. 

Disinfection  may  be  carried  out  in  several  ways : — 

1.  By  burning  or  exposure  to  high  temperatures  (hot  air, 
steam,  boihng). 

2.  By  the  action  of  oxidizing  agents  (atmospheric  air,  ozone, 
nitric  peroxide,  peroxide  of  hydrogen,  chlorine,  chlorates,  bleach- 
ing powder,  etc.).  Oxygen  burns  up  all  organic  matter  into 
carbonic  acid,  ammonia,  and  water;  but  it  exercises  no  selective 
influence  on  bacteria.  Certain  organisms  die  at  once  in  atmo- 
spheres containing  oxygen;  some  cannot  exist  in  the  absence  of 
oxygen;  while  others  are  indifferent  either  to  its  presence  or  absence. 

Fresh  air  is  universally  regarded  as  a  powerful,  if  slow,  disin- 
fectant. Its  powers  in  this  respect  are  mainly  due  to  the  molecular 
oxygen  contained  in  it;  if,  however,  oxygen  can  be  Hberatcd  in  a 
nascent  atomic  condition,  its  activity  considerably  exceeds  that 
of  atmospheric  oxygen.  The  disinfectant  properties  of  fresh  air 
are  enhanced  by  the  actinic  rays  of  sunlight.  Rays  of  sunlight, 
in  the  presence  of  air  and  moisture,  will  destroy  even  resistant 
organisms  after  varying  periods  of  exposure;  but  there  is  no 
evidence  of  the  destruction  of  the  spores  of  anthrax  bacilli  by  this 
means.  The  actinic  rays  probably  exert  their  effects  by  promoting 
oxidation,  or  possibly  by  leading  to  the  production  of  small 
quantities  of  ozone  and  peroxide  of  hydrogen — two  powerful 


DISINFFXTION  6oi 

oxidizers.     The  ultra-violet  rays  are  much  inure  powerful  in  this 
respect  than  the  infra-red. 

3.  By  the  action  of  reducing  agents  (sulphurous  acid,  ferrous 
sulphate,  etc.). 

4.  By  agents  which  enter  into  combination  with  albumin 
(perchloride  of  mercury,  sulphate  of  copper,  etc.).  These  kill 
by  their  action  on  the  albumin  of  the  organism;  or,  by  pre- 
cipitating the  albuminous  matter  around  the  germ,  they  may 
rob  it  of  its  nourishment. 

5.  By  agents  which  exercise  a  direct  poisonous  effect  on 
micro-organisms  (perchloride  of  mercury,  iodide  of  mercury, 
phenols,  etc.). 

Deodorants  act  by  absorbing  (slaked  lime),  condensing  (char- 
coal), or  oxidizing  (permanganate  of  potash)  odorous  gases  or 
vapours,  such  as  sulphuretted  hydrogen,  ammonia,  the  com- 
pound ammonias,  and  some  organic  vapours.  Many  deodorants 
(charcoal,  permanganate  of  potash,  etc.)  possess  but  little  dis- 
infecting power. 

Having  regard  to  the  circumstances  of  actual  practice,  it 
must  be  borne  in  mind  that  no  disinfectant  can  be  expected  to 
act  instantaneously,  for  it  cannot  be  brought  to  bear  in  sufficient 
volume  upon  all  the  organisms  present;  hence  the  agent  should 
possess  some  degree  of  permanence  in  its  action.  Those  disin- 
fectants, for  instance,  which,  by  giving  up  oxygen,  soon  expend 
themselves  in  contact  with  organic  matter,  are  inferior  to  sub- 
stances like  carbohc  acid,  which  have  greater  permanence  of 
action,  and  exert  a  direct  toxic  effect  upon  organisms.  In 
practice,  no  agent  of  the  kind  which  does  not  perform  its  functions 
within  a  limit  of  about  thirty  minutes  can  be  regarded  as  satis- 
factory. Preference  should  be  given  to  one  which  is  non- 
poisonous  to  the  higher  forms  of  animal  life,  cheap,  readily 
soluble  in  water,  and  otherwise  convenient  in  use.  It  should 
not  injure  utensils  in  which  it  is  placed,  or  articles  exposed  to  its 
action,  nor  should  it  possess  an  offensive  odour. 

Burning. — This,  the  most  efficient  means  of  disinfection,  can 
be  applied  often  in  the  sick-room  itself  to  all  articles  of  little 
or  no  value.  Rags  used  for  receiving  the  discharges  from  the 
mouth  and  nose,  or  from  the  open  wounds  of  patients  in  an  in- 
fectious state,  should  be  promptly  placed  upon  the  fire,  before 
they  have  time  to  become  dry.  Old  mattresses,  pillows,  and 
other  large  articles  which  are  not  required  for  further  use  should 


602  HYGIENE    AND    PUBLIC    HEALTH 

be  saturated  with  paraffin  and  burned.  This  is  generally  done 
in  the  small  destructor  which  forms  part  of  a  disinfecting  station. 
The  stools  of  cholera  and  enteric  fever  patients  may  be  cremated ; 
if  no  destructor  be  available  for  the  purpose,  they  must  be  mixed 
with  plenty  of  sawdust,  and  the  mixture  then  saturated  with 
paraffin  and  ignited. 

Boiling. — Infectious  material  which  can  be  boiled  for  twenty 
minutes  is  thereby  as  a  rule  efficiently  disinfected;  but  there  is 
evidence  that  some  of  the  more  resistant  organisms  (B.  anthracis) 
may  resist  boiling  for  longer  periods.  This  method  is  most  fre- 
quently employed  for  the  purpose  of  disinfecting  bed  and  body 
linen.  It  is  important  to  bear  in  mind  that  if  the  articles  are 
stained  with  albuminous  matter,  such  as  blood  or  fieces,  the 
boihng  tends  to  fix  the  stains;  on  this  account  the  stains  should 
first  be  removed  by  soaking  in  cold  water,  and,  if  necessary,  by 
rubbing  with  a  little  soap. 

Faeces  have  been  disinfected  in  cauldrons  by  means  of  steam, 
or  by  boihng  with  strong  solutions  of  Izal,  etc. 

Hot  Air. — This  method  of  disinfecting  textile  articles  is  rapidly 
falling  into  disuse;  for  the  high  temperature  required  to  destroy 
resistant  organisms  injures  the  articles  exposed,  and  an  incon- 
veniently long  period  of  exposure  is  necessary  to  secure  sufficient 
penetration  of  the  heat  into  the  interior  of  bulky  objects.  Dry 
air  being  a  bad  conductor,  the  heat  penetrates  slowly  and  imper- 
fectly. Resistant  bacteria  placed  in  the  interior  of  mattresses 
may  survive  an  exposure  of  some  three  hours,  even  when  the 
temperature  to  which  the  surfaces  of  the  mattresses  are  exposed 
reaches  140°  C. ;  but  a  temperature  exceeding  120°  C.  would 
certainly  damage  many  articles,  such  as  wool,  leather,  and  silk. 
By  this  method,  therefore,  fabrics  are  often  damaged  by  scorch- 
ing; but,  short  of  this,  they  are  liable  to  suffer  a  change  in  colour, 
to  shrink,  and  to  lose  elasticity  and  gloss.  Stains,  especially 
those  of  an  albuminous  nature  (blood,  faeces),  are  liable  to  become 
fixed;  but  these  can  always  be  removed  prior  to  disinfection  by 
soaking  and  subsequent  rubbing  in  cold  water.  Fusible  sub- 
stances, such  as  glue  and  wax,  are  melted,  and  the  overdrying 
renders  many  articles  brittle. 

Dry  heat  is  serviceable  for  articles  of  leather,  morocco,  and 
india-rubber,  and  for  furs,  books,  and  some  other  objects  which 
are  injured  by  the  employment  of  the  more  efficient  method  next 
to  be  described. 


DISINFECTION  603 

Steam.  —  Steam  under  pressure  penetrates  into  bulky  and 
badly  conducting  articles,  such  as  mattresses,  pillows,  and 
clothing,  far  more  rapidly  than  dry  heat.  As  such  steam 
penetrates  into  the  interstices  of  a  cold  body,  it  undergoes  con- 
densation, and  imparts  its  latent  heat  instantaneously  to  the 
cold  objects  in  contact  with  it.  When  thus  condensed  into 
water,  it  occupies  only  a  very  small  fraction  (about  tisVo)  of 
its  former  volume.  To  fill  the  vacuum  thus  formed,  more 
steam  presses  forward,  in  its  turn  yielding  up  its  latent  heat 
and  becoming  condensed,  and  so  on  until  the  whole  mass  has 
been  penetrated.  On  the  other  hand,  hot  air  in  yielding  up  its 
heat  undergoes  contraction  in  volume  only  to  a  very  small 
extent  as  compared  with  that  undergone  by  steam  in  con- 
densing to  water. 

Body  lice  and  their  eggs  are  destroyed  by  exposure  to  steam 
at  100°  C.  for  ten  minutes,  or  to  boihng  water  for  five  minutes. 

The  various  stoves  now  employed  for  disinfecting  by  steam 
may  be  classified  as  follows: 

1.  Stoves  in  which  steam  without  pressure  is  employed.  These 
are  of  course  cheaper,  but,  as  the  temperature  of  the  steam  does 
not  exceed  100°  C,  less  efficient  than — 

2.  Those  in  which  steam  at  low  pressure  (2,  3,  or  5  pounds  per 
square  inch)  is  used.  Although  the  temperature  of  110°  C, 
which  can  be  reached  by  these  stoves,  is  sufficient  for  most 
purposes,  a  higher  temperature  can  never  be  employed  in 
them.  These  stoves,  though  cheaper,  are  therefore  less  efficient 
than — 

3.  Those  in  which  steam  at  high  pressure  (10  pounds  and  over) 
can  be  employed.  A  temperature  of  115°  C.  to  120°  C. — which 
should  not  be  exceeded — can  be  obtained  in  these  stoves;  and 
an  exposure  of  articles  for  from  a  quarter  to  half  an  hour  will 
suffice  for  their  disinfection.  The  higher  the  pressure  of  the 
steam,  the  more  rapid  the  penetration,  and  the  less  time  required 
for  disinfection. 

The  steam,  which  must  be  free  from  air,  may  be  current  or  con- 
fined. Current  steam  serves  to  drive  the  air  out  of  the  interstices 
of  fabrics,  and  thus  to  aid  penetration;  but  since  more  steam  is 
used,  more  fuel  is  consumed.  In  the  stoves  using  steam  confined 
under  pressure,  the  steam  should  be  allowed  to  escape  from 
time  to  time,  as  this  serves  to  displace  the  air  (otherwise  often 
compressed)  in  the  centre  of  bulky  articles.     The  greatest  effect 


604  HYGIENE   AND    PUBLIC   HEALTH 

is  of  course  produced  when  the  steam  has  been  under  very  high 
pressure. 

The  steam  employed  may  be  saturated  or  superheated,  the 
former  being  far  preferable  to  the  latter,  owing  to  its  more  rapid 
and  thorough  penetration.  The  use  of  superheated  steam,  there- 
fore, involves  a  longer  exposure  in  the  chamber,  and  a  greater 
expenditure  of  fuel,  in  addition  to  an  increased  liability  to  injure 
articles.  The  distinction  between  saturated  and  superheated 
steam  is  an  important  one.  By  increasing  the  pressure,  steam 
may  be  generated  at  temperatures  exceeding  ioo°  C,  but  it 
always  remains  saturated  steam;  if,  however,  the  steam  is 
further  raised  in  temperature  without  increasing  the  pressure,  as 
may  be  done  by  bringing  it  into  contact  with  a  surface  raised 
above  its  own  temperature,  it  becomes  superheated.  Now,  super- 
heated steam  has  properties  similar  to  those  of  a  gas,  and  will  not 
condense  until  it  has  parted  with  all  its  "  superheat  "  by  the 
slow  process  of  conduction;  whereas  saturated  steam,  being  a 
vapour,  condenses  at  once  on  objects  which  are  but  sHghtly 
cooler  than  itself.  Since  penetration  depends  upon  condensa- 
tion, the  disinfectant  value  of  superheated  steam  does  not  much 
exceed  that  of  dry  air.  The  amount  of  "  superheat  "  which 
is  generally  given  to  the  steam  in  practice  is  not,  however, 
sufficient  to  cause  it  to  act  very  differently  from  saturated 
steam. 

Steam,  therefore,  should  not  be  superheated,  or  only  to  so 
slight  an  extent  that  it  can  at  once  condense  upon  any  object 
slightly  cooler  than  itself. 

The  time  required  for  disinfection  by  steam  obviously  depends 
on  the  organism  to  be  destroyed,  the  bulk  of  the  infected  articles, 
and  the  pressure  of  the  steam  employed.  The  best  researches 
indicate  a  temperature  of  115°  to  120°  C.  for  twenty  minutes, 
as  alone  trustworthy  in  all  cases. 

Satisfactory  provision  must  be  made  to  ensure  that  the  infected 
articles  are  not  allowed  to  become  too  wet,  as  otherwise  colours 
are  liable  to  run;  and  the  disinfected  articles  should  be  fairly 
dry  on  removal. 

By  bearing  the  foregoing  facts  in  mind,  an  opinion  upon  the 
suitability  and  efficiency  of  any  steam  disinfector  can  be  readily 
formed.  The  rapidity  of  the  penetration  of  heat  into  articles  is 
ascertained  by  placing  within  them  a  thermometer,  which  when 
the  required  temperature  is  reached  causes  a  bell  to  ring  by  reason 


DISINFECTION  605 

of  the  mercury  completing  the  circuit  of  an  electric  current  from 
a  battery.  The  efficiency  of  the  provision  for  drying  the  articles 
is  gauged  by  the  amount  of  moisture  remaining  in  them  after 
removal  from  the  stove,  as  calculated  by  the  increase  in  weight 
of  the  article.  The  maximum  temperature  reached  in  the  stove 
and  the  uniform  distribution  of  the  heat  may  be  tested  by  means 
of  recently  standardized  maximum  thermometers  wrapped  up 
in  blankets  and  exposed  in  the  stove;  and  the  pressure  within 
the  stove  can  be  ascertained  at  any  time  by  the  external  pressure 
gauge. 

The  construction  of  the  apparatus  must  be  such  as  to  combine 
simplicity  of  design  with  facility  of  management — so  that  highly 
skilled  labour  is  not  an  absolute  essential. 

The  machines  made  under  Washington  Lyon's  patents  are 
most  used  in  this  country.  The  "  Nottingham  "  stove,  made  by 
Goddard,  Massey,  and  Warner,  consists  of  a  rectangular  chamber 
with  a  double  wall  or  jacket,  the  lower  part  of  the  jacket  con- 
taining water  and  serving  as  the  boiler.  Steam  is  made  to 
occupy  the  space  between  the  double  wall,  at  a  pressure  of  some 
20  pounds;  this  serves  to  heat  the  walls  of  the  chamber,  and  to  a 
less  extent  the  articles  inside  it,  so  that  when  the  steam,  also  at 
a  pressure  of  about  20  pounds,  is  allowed  to  fill  the  chamber, 
the  condensation  which  would  otherwise  take  place  upon  the 
walls  of  the  chamber  is  prevented,  and  only  a  slight  initial 
condensation  on  the  surface  of  the  now  heated  infected  articles 
results.  Articles  arc  thus  kept  comparatively  dry;  but  before 
they  are  removed  they  are  further  dried,  either  by  allowing  the 
steam  to  remain  in  the  jacket,  after  that  in  the  interior  of  the 
chamber  has  been  removed,  or  preferably  by  drawing  off  the 
steam  from  the  chamber  and  then  drying  by  means  of  a  current 
of  hot  air.  The  hot  air  (heated  by  steam,  so  as  to  limit  the 
temperature  and  guard  against  scorching)  can  be  drawn  into 
the  chamber  by  means  of  a  vacuum  apparatus.  Steam  exhausts 
are  employed  in  some  apparatus  to  produce  a  partial  vacuum 
in  the  chamber  prior  to  the  admission  of  the  steam,  and 
these  greatly  promote,  by  the  withdrawal  of  air,  the  rapidity 
of  penetration.  One  of  these  stoves,  of  medium  size,  costs 
about  £250. 

The  stove  {Washington-Lyon)  made  by  Manlove,  Alhott  and 
Co.,  is  oval  in  section,  and  the  steam  is  led  into  the  jacket  and 
the  chamber  of  the  stove  from  a  special  detached  boiler.     The 


6o6  HYGIENE    AND    PUBLIC   HEALTH 

disinfector  is  fitted  with  a  vacuum  apparatus  and  hot  -  air 
chamber.  In  working,  steam  is  first  admitted  into  the  jacket; 
then  a  vacuum  is  created  in  the  oven,  so  as  to  withdraw  air. 
Steam  is  then  admitted  into  the  oven,  and  a  pressure  equivalent 
to  a  temperature  of  140°  F.  or  150°  F.  maintained  for  twenty 
minutes.  A  vacuum  is  again  produced,  and  finally  air  heated 
by  passing  over  the  steam  coils  in  the  hot-air  chamber  is  ad- 
mitted, so  as  to  dry  the  steam-heated  articles.  The  whole 
process  occupies  rather  over  thirty  minutes  from  the  time  the 
infected  articles  are  introduced  into  the  oven.  There  is  an 
advantage  in  having  a  separate  detached  boiler,  which  can  be 
readily  inspected  and  tested  for  boiler  insurance  purposes. 

The  Eqtiifex  Disinfector  is  a  non- jacketed  cylinder,  into  which 
steam  at  a  pressure  of  10  pounds,  and  a  temperature  of  about 
115°  C,  is  admitted.  The  steam  which  first  enters  is  allowed 
to  blow  off,  so  as  to  displace  the  air  in  the  chamber;  and  the 
pressure  of  the  steam  can  be  intermitted  so  as  to  facilitate 
penetration.  Condensation  upon  the  walls  of  the  cyHnder  is 
prevented  by  an  arrangement  of  coils  inside  the  chamber  which 
are  first  filled  with  steam  at  high  pressure;  and  articles  are 
subsequently  dried  by  hot  air.  A  low-pressure  apparatus  is  also 
made  of  the  Equifex  type.  A  medium  size  Equifex  stove  costs 
about  £250. 

Reek's  Stove  is  a  non-jacketed  cylinder,  in  which  current  steam 
is  employed  at  about  i|  pounds  pressure  (about  105°  C).  The 
apparatus  is  very  simple  and  handy.  Its  special  feature  is  an 
arrangement  for  the  introduction  at  the  top  of  the  chamber  of 
a  shower  of  cold  water,  which  falls  upon  an  umbrella-shaped 
plate,  and  is  thus  diverted  from  the  articles  which  have  been 
disinfected.  The  sudden  introduction  of  the  cold  shower  after 
the  goods  have  been  disinfected  causes  a  rapid  condensation  of 
all  live  steam,  which  is  carried  away  with  the  water  through 
an  outlet  in  the  bottom  of  the  stove,  air  entering  automatically 
through  a  valve  in  the  front  of  the  apparatus  to  restore  the  partial 
vacuum  produced  by  the  condensation  of  the  steam.  In  this 
way  the  chamber  is  freed  of  the  steam,  and  the  articles  are  dried  ; 
but  the  drying  is  not  quite  so  complete  as  in  most  other  forms 
of  apparatus.  The  original  stove  has  been  improved  by  sur- 
rounding the  disinfecting  chamber  with  a  water-jacket,  by 
which  sufficient  heat  is  retained  to  dry  the  clothes  when  air  is 
admitted, 


DISINFECTION  607 

Thresh's  Stove. — Here  current  steam  is  employed,  without 
pressure,  at  a  temperature  of  about  los""  C,  the  "  superheat  " 
being  obtained  by  using  in  the  boiler  a  calcium  chloride  solution, 
the  boiling-point  of  which  is  considerably  above  that  of  water. 
The  lower  part  of  the  jacket  of  the  cylinder,  which  contains  the 
saline  solution,  acts  as  the  boiler,  and  is  heated  by  a  small  furnace. 
The  steam,  which  enters  the  chamber,  escapes  continuously 
through  a  chimney.  For  the  subsequent  displacement  of  the 
steam  and  for  the  drying  of  the  articles,  hot  air  is  drawn  into  the 
chamber  through  a  coil  of  tubes,  which  is  surrounded  and  heated 
by  the  boiling  solution.     The  medium  size  stove  costs  about 

A  current  saturated  pressure  steam  disinfector  (Delepine- 
Jones)  has  been  lately  introduced  by  the  Thresh  Disinfector 
Company. 

Steam  disinfectors  are  made  portable,  so  that  they  may  be 
taken  to  infected  premises,  or  be  moved  from  village  to  village. 
Their  cost  varies  from  about  60  to  150  guineas,  according  to 
the  size. 

In  all  those  apparatus  in  which  steam  is  employed  at  a  low 
pressure  or  in  a  superheated  form  {i.e.,  at  temperatures  not 
exceeding  104°  to  110°  C),  objects  should  be  exposed  for  at  least 
one  hour. 

A  disinfecting  station  should  comprise: 

1.  Two  rooms  completely  separated  from  each  other  by  a  wall, 
into  which  the  stove  is  built,  so  that  it  communicates  with  both 
rooms.  The  infected  articles  are  brought  into  one  room  and 
placed  in  the  stove,  and  after  disinfection  they  are  removed  from 
the  other  end  of  the  stove,  which  opens  into  the  non-infected 
room.  No  infectious  material  must  be  allowed  to  enter  the  non- 
infected  room,  and  there  should  be  no  direct  means  of  com- 
munication between  it  and  the  infected  room.  The  workers  in 
the  infected  side  should  always  wear  "  overalls."  The  floors 
and  walls  of  both  rooms  should  be  made  of  some  smooth  and 
non-porous  material,  which  can  be  readily  and  efficiently  cleansed 
by  water;  and  exceptionally  good  provision  should  be  made  for 
ventilation  and  light. 

2.  An  incinerator  or  destructor,  provided  with  a  small  second 
fire  to  cremate  the  products  of  imperfect  combustion  before  they 
pass  up  the  flue. 

3.  Separate  sheds  must  be  provided  for  [a]  vans  employed  to 


6o8 


HYGIENE   AND   PUBLIC   HEALTH 


bring  in  infected  articles,  and  {b)  those  employed  to  return  the 
disinfected  articles. 
4.  A  laundry  and  bath-room  sometimes  form  part  of  a  dis- 


infecting station,  a  charge  being  made  for  any  laundry  work 
undertaken. 


DISINFECTION 


609 


Liquid  Disinfectants. 
Solutions  of  the  following  substances  are  employed: 
Pcrcli'oridc  of  Mercury  (HgClg,  corrosive  sublimate). — This  is 


WmSm»mW»i&h>.aimrismmSiii'.»..^. 


one  of  the  most  powerful  and  one  of  the  most  convenient  dis- 
infectant  agents  known.      It  forms  a  colourless,   non-odorous 

3y 


6lO  HYGIENE   AND   PUBLIC   HEALTH 

solution,  which  is,  however,  poisonous  to  human  beings.  Unless 
the  solution  is  acidulated,  it  has  a  marked  precipitating  effect 
upon  albumin,  and  its  power  of  penetration  into  the  interior  of 
particles  of  organic  matter  is  thereby  limited. 

It  acts  as  a  direct  poison  to  bacteria,  and  also  exerts  its  disin- 
fectant action  by  coagulating  their  protoplasm. 

One  part  of  the  salt  to  i,ooo  parts  of  water  constitutes  a 
stronger  disinfectant  than  even  5  per  cent,  carbolic  solution, 
and  it  is  trustworthy  for  the  disinfection  of  non-spore-bearing 
bacteria;  but  i  in  500  is  necessary  for  spore-bearing  bacteria. 

The  solution  should  not  be  stored  in  metal  receptacles,  as 
it  corrodes  them,  and  is  then  liable  to  decomposition.  It  should 
always  be  made  distinctly  acid,  and  a  little  colouring  matter 
should  be  added  to  guard  against  its  being  swallowed  in  mistake 
for  water.  For  the  same  reason  it  should  be  placed  in  dark  blue 
bottles  bearing  a  large  poison  label. 

Half  an  ounce  of  perchloride  of  mercury,  i  ounce  of  hydro- 
chloric acid,  and  i  grain  of  aniline  blue,  to  3  gallons  of  water,  is 
a  mixture  which  costs  about  fourpence,  and  furnishes  a  non- 
staining  disinfectant  solution,  containing  about  i  in  1,000  of  the 
perchloride. 

The  salt  has  been  made  up  into  tablets  of  about  20  grains 
each  in  weight,  so  that  one  tablet  to  a  quart  of  water  furnishes 
a  solution  of  i  in  1,000  of  the  perchloride.  This  constitutes  a 
portable  form,  convenient  to  travellers  and  troops  on  the  march ; 
but  there  is  risk  in  introducing  the  tablets,  which  look  very  like 
sweets,  into  ordinary  households. 

Mercuric  Iodide  (Hgig)  is  less  poisonous  than  the  perchloride, 
and  does  not  precipitate  albumin  to  the  same  extent.  Its  dis- 
infectant power  is  at  least  equal  to,  and  there  is  evidence  that  it 
even  excels,  that  of  the  perchloride.  It  constitutes  an  excellent 
disinfectant  solution  for  the  hands.  Although  insoluble  in  pure 
water,  it  is  readily  soluble  in  the  presence  of  excess  of  iodide 
of  potassium.     Like  the  perchloride,  it  attacks  metals. 

Phenols  are  obtained  from  tar  distillates  as  dark  oily  liquids, 
which  contain  in  the  crude  state,  besides  the  many  members  of 
the  phenol  group,  the  neutral  tar  oils.  Phenols  are  poisonous, 
possess  a  caustic  action,  and  coagulate  albumin. 

Carbolic  Acid  (CgHgO)  is  the  member  of  the  group  most  em- 
ployed for  disinfecting  purposes,  although  its  powers  are  slightly 
inferior  to  those  of  cresylic  acid   (C^HyO).      It  is  not  a  true 


DISINFECTION  6ll 

deodorant,  but  it  masks  offensive  gases  and  vapours  by  its  own 
strong  and  unpleasant  odour.  A  5  per  cent,  solution  at  least 
must  be  employed  against  resistant  organisms.  Many  trade  i)ro- 
ducts,  consisting  of  oils  procured  from  the  destructive  distillation 
of  coal,  are  on  the  market,  and  they  for  the  most  part  possess 
disinfectant  value  similar  to  that  of  carbohc  acid.  They  are 
mostly  dark  brown  liquids  which,  when  added  to  water,  form 
milky  emulsions,  one  advantage  in  their  use  being  that  they  are 
practically  non-poisonous,  and  somewhat  cheaper  than  pure 
carbolic  acid.  Izal,  containing  a  body  allied  to  the  phenols  of  the 
carbolic  acid  scries,  is  a  powerful  and  valuable  disinfectant ;  it  is 
practically  non-poisonous.  It  mixes  well  with  water  and  has  an 
agreeable  odour.  According  to  Klein,  an  emulsion  of  i  in  200 
disinfects  non-spore-bearing  organisms  in  5  minutes,  and  a  10  per 
cent,  solution  kills  even  the  virulent  spores  of  Bacillus  anthracis 
in  about  15  minutes.  Cyllin  is  very  similar  to  Izal  in  its  disinfec- 
tant property.  Saprol  is  a  dark  brown  oily  fluid,  much  used  in 
Germany;  it  appears  to  be  of  similar  strength  to  carbolic  acid, 
and  possesses  the  advantage  that,  while  its  contained  phenols 
mix  with  a  liquid,  an  oily  film  floats  over  its  surface. 

The  disinfectants,  like  izal,  cyllin,  lysol,  sanitas-okol,  sanitas- 
bactox,  kerol,  MacDougal's  M.O.H.  fluid,  Lawes'  fluid,  Cooke's 
cofectant  fluid,  Jeyes'  fluid,  etc.,  which  are  coal  tar  derivatives, 
contain  varying  proportions  of  phenols,  neutral  oils,  resins  and 
fatty  acids,  and  water.  Most  of  them  are  able  to  form  emulsions 
with  water  by  reason  of  the  presence  of  the  resins  and  fatty  acids; 
but  in  some  a  non-resinous  emulsifier,  such  as  gelatine,  is  used. 
It  seems  probable  that  the  activity  of  these  disinfectants  is  in 
part  dependent  on  the  fineness  of  the  emulsification  formed  when 
the  crude  article  is  mixed  with  water.  The  fine  particles  of  an 
emulsion  are  in  a  constant  state  of  Brownian  movement,  and  thus 
a  kind  of  bombardment  of  the  micro-organisms  is  kept  up  by 
these  incessant  movements  of  the  disinfectant  molecules.  In 
the  presence  of  organic  matter,  however,  whether  in  solution  or 
in  suspension,  the  Brownian  movements  of  the  particles  of  the 
emulsion  appear  to  be  impeded,  with  the  result  that  the  germi- 
cidal action  of  the  emulsified  disinfectant  is  not  nearly  so  great 
as  when  it  has  to  act  only  on  the  naked  organism.  Where  the 
organisms  to  be  destroyed  are  in  the  presence  of  an  excess  of 
organic  matter,  it  is  possible  that  emulsions  may  have  but  little 
advantage  over  clear  solutions. 


6l2  HYGIENE    AND   PUBLIC   HEALTH 

Chloride  of  Lime  (CaClgO,  bleaching  powder)  is  a  mixture  of 
chloride  and  hypochlorite  of  calcium,  and  should  contain  about 
35  per  cent,  of  available  chlorine.  It  gives  off  a  most  unpleasant 
odour.  Chloride  of  lime  solution  is  made  by  first  stirring  up 
the  bleaching  powder  with  a  little  water  so  as  to  make  a  thick 
cream,  and  then  diluting  to  the  required  extent.  The  solution 
exerts  a  corrosive  action  on  metals;  it  tends  to  dissolve  the 
albumin  of  faecal  and  other  matter,  and  its  powers  may  be 
entirely  exhausted  upon  such  organic  matter,  bacteria  conse- 
quently escaping.  The  disinfectant  and  deodorizing  action 
of  the  solution  is  due  to  the  fact  that,  in  presence  of  moisture 
and  carbonic  or  other  acids,  hypochlorous  acid  (HCIO)  is  liberated, 
and  this  acts  as  an  oxidizing  agent  by  splitting  up  into  HCl 
and  O.  A  15  per  cent,  solution  of  the  powder  (about  2^  ounces 
to  the  gallon),  containing  05  per  cent,  of  available  chlorine,  should 
generally  be  employed,  except  when  dealing  with  organisms  whose 
resistance  is  known  to  be  slight;  in  such  cases  experiments  show 
that  a  solution  containing  i  part  of  chlorine  in  1,000  will  suffice. 

Sodium  Hypochlorite,  like  bleaching  powder,  possesses  consider- 
able disinfecting  power  on  account  of  its  available  chlorine.  The 
strength  at  which  it  should  be  employed  must  be  governed  by 
the  fact  that  the  solution  should  contain  in  practice  at  least  05 
per  cent,  of  available  chlorine,  except  where  organisms  of  little 
resistance  are  to  be  dealt  with.  A  liquid  on  the  market,  sold  as 
Chloros,  contains  10  per  cent,  of  available  chlorine.  Solutions 
of  hypochlorites  are  apt  to  lose  their  strength  somewhat  on 
keeping ;  they  should  therefore  be  kept  tightly  stoppered  in  a 
dark  place.  The  absence  of  lime  renders  a  solution  of  sodium 
hypochlorite  preferable  to  one  of  bleaching  powder,  when  the 
disinfectant  is  to  be  emptied  down  the  drains. 

Hypochlorous  Acid  is  formed  by  the  electrolysis  of  sea-water 
(Hermite  process),  which  is  thereby  constituted  a  powerful 
deodorizing,  but  weak  and  unstable,  disinfectant  solution.  The 
electrolysis  of  a  solution  of  magnesium  and  sodium  chlorides, 
produces  a  mixture  containing  available  chlorine  in  a  more 
stable  condition  than  is  the  case  with  electrolysed  sea-water. 

Hydrochloric  and  other  mineral  acids  are  markedly  disinfectant 
when  employed  in  such  strengths  as  will  give  the  solution  a. 
marked  acid  reaction. 

Sulphate  of  Copper  (CUSO4). — In  5  per  cent,  solution  this  salt: 
is  a  powerful  disinfectant.     It  acts  by  coagulating  albu'/jip  apdi 


DISINFECTION  613 

by  exerting  a  poisonous  action  on  bacteria.  It  will  absorb 
ammonia,  the  compound  ammonias,  sulphuretted  hydrogen,  etc., 
and  is  therefore  a  useful  deodorant. 

Chloride  of  Zinc  (ZnCy  is  a  poisonous  salt  with  very  similar 
properties  to  those  of  sulphate  of  copper.  A  10  per  cent,  solution, 
to  which  a  little  hydrochloric  acid  has  been  added,  should  be 
employed  where  spores  are  concerned,  but  5  per  cent,  will  suffice 
for  non-spore-bearing  bacteria;  it  has,  however,  a  corrosive 
action  if  used  in  solutions  containing  much  more  than  5  per  cent, 
of  the  salt.  Its  disinfectant  powers  are  somewhat  inferior  to 
those  of  sulphate  of  copper,  but  they  are  far  superior  to  those 
of  ferrous  sulphate.  "  Burnett's  Fluid  "  contains  about  50  per 
cent,  of  ZnCl2. 

Ferrous  Sulphate  (FeS047H20,  Green  Copperas)  acts  mainly 
by  its  reducing  action  while  taking  up  oxygen  to  become  a  ferric 
salt.  It  is  a  feeble  disinfectant  unless  used  in  great  strength 
(20  to  30  per  cent.),  but  it  is  a  good  deodorant,  absorbing  ammonia 
and  sulphuretted  hydrogen.  In  practice  it  is  suitable  only  for 
excreta,  as  it  stains  badly,  and  tends  to  form  iron  moulds.  The 
same  general  remarks  apply  to  FcgCle,  which  is,  however,  a  feeble 
oxidizer. 

"  Chinosol  "  is  a  readily  soluble  crystalline  yellow  powder, 
with  a  slight  aromatic  odour,  belonging  to  the  quinoline  group. 
Its  solution  is  non-poisonous  and  non-corrosive,  does  not  coagu- 
late albumin,  and  possesses  marked  deodorant  properties.  There 
is  satisfactory  experimental  evidence  to  show  that  a  i  in  1,000 
solution  will  rank  with  perchloride  of  mercury  solution  of  similar 
strength. 

Potassium  Permanganate  (K2Mn20y)  is  an  oxidizing  agent  which 
can  only  be  used  in  practice  in  weak  solutions  as  a  deodorant, 
since  a  5  per  cent,  solution,  at  least,  is  required  for  the  dis- 
infection of  resistant  organisms.  A  solution  of  this  strength 
would  be  expensive,  and  would  stain  everything  with  which  it 
came  in  contact.  Gases,  hke  sulphuretted  hydrogen,  reducing 
salts  in  solution,  and  the  more  unstable  organic  matter, 
first  rob  the  permanganate  of  its  oxygen;  and  the  whole  of 
the  permanganic  radical  may  be  reduced  to  black  manganic 
oxide,  or  even  to  a  lower  oxide,  before  the  bacteria  are 
destroyed. 

"  Candy's  Red  Fluid  "  is  a  mixture  of  the  permanganate  and 
sulphate  of  soda. 


6l4  HYGIENE    AND   PUBLIC    HEALTH 

Formic  Aldehyde  (CHOH),  in  solution  of  i  to  2  per  cent.,  is  a 
liquid  giving  off  an  irritating  odour,  and  ranking  high  as  a  rapid 
disinfectant  and  deodorant;  it  costs  far  less  than  carbolic  acid 
of  equal  disinfecting  strength.  An  aldehyde  is  an  alcohol 
dehydrogenated ;  thus,  wood  spirit  (methyl  alcohol,  CH3OH), 
when  deprived  of  Hg,  becomes  CHOH,  called  formic  aldehyde 
because  it  very  readily  changes  to  formic  acid  (CHOOH).  In 
aqueous  solution  the  gas  can  be  concentrated  to  about  40  per 
cent.,  in  which  state  it  is  sold  as  "  Formalin." 

Sanitas  Fluid  has  the  odour  of  pine  wood  and  is  a  practicall}^ 
non-poisonous  liquid.  Used  in  the  strength  of  10  per  cent,  in 
water  it  is  said  to  be  capable  of  destroying  non-spore-bearing 
organisms  in  10  minutes.  It  is  one  of  the  less  powerful  disin- 
fectants. 

Gaseous  Disinfectants. 

Formic  Aldehyde  is  also  used  as  a  gaseous  disinfectant.  The 
aldehyde  vapours,  which  are  non-poisonous,  but  very  irritating 
to  the  eyes  and  throat,  are  powerfully  disinfectant  and  deodorant. 
So  far  as  their  application  for  the  purpose  of  the  surface  disin- 
fection of  rooms  is  concerned,  they  may  be  regarded  as  likely 
to  fulfil  all  the  requirements  of  general  practice,  if  they  are 
employed  in  sufficient  quantities.  Formic  aldehyde  is  more 
rapidly  disinfectant  than  equal  quantities  of  sulphurous  acid, 
and  it  does  not  affect  colours  or  (with  the  exception  of  iron  or 
steel)  metallic  surfaces,  although  it  fixes  stains  of  blood  or  faeces. 
It  is  somewhat  difficult  to  confine  to  the  room,  but  there  is  no 
danger  and  little  difficulty  attending  its  practical  application 
if  the  rooms  are  well  sealed  up. 

Formalin  vapour  is  most  efficacious  at  a  temperature  of  70°  F. 
and  a  humidity  of  70  per  cent. ;  if  temperature  and  humidity  are 
much  below  these  optimum  conditions,  the  disinfection  can  liardly 
be  regarded  as  reliable. 

The  production  of  the  gas  by  means  of  specially  devised  methyl- 
alcohol  lamps  is  often  imperfect  and  unsatisfactory  in  practice. 
In  these  the  aldehyde  is  generated  by  allowing  the  vapour  of 
wood  alcohol,  well  mixed  with  air,  to  pass  over  the  surface  of 
red-hot  platinum,  when  the  alcohol  is  converted  into  aldehyde 
and  water.  The  gas  can  best  be  liberated  from  formalin  by 
means  of  Trillat's  apparatus,  in  which  the  formalin  is  heated 
under  pressure  in   an   autoclave.     A  little  calcium  chloride   is 


DISINFECTION 


615 


placed  in  the  solution,  which  is  then  known  as  "  formo-chlorol," 
and  as  the  boiling  point  of  the  calcium  chloride  solution  is  above 
100°  C,  and  the  aldehyde  is  given  off  below  that  temperature,  it 
may  in  this  manner  be  obtained  in  a  practically  dry  state. 
When  the  attached  pressure  gauge  registers  a  pressure  of  40 
pounds  in  the  autoclave,  the  vapours  are  allowed  to  escape 
through  a  long  thin  copper  tube,  which  is  passed  through  the 
keyhole  into  the  infected  compartment.  The  apparatus  costs 
about  ;^i8.  Half  an  hour  is  required  to  get  up  the  necessary 
pressure,  and  in  an  ordinary  sized  room  the  vapours  would  be 
allowed  to  escape  for  about  half  an  hour.  From  ^  to  i  litre  of 
formo-chlorol  should  be  employed  for  every  1,000  cubic  feet,  an 
extra  quantity  of  the  liquid  being  used  in  the  autoclave  to  guard 
against  danger  from  drying  up.  About  twenty  minutes  is 
required  to  rid  each  litre  of  formo-chlorol  of  its  aldehyde. 

This  constitutes  the  best  known  means  of  liberating  large 
quantities  of  the  aldehyde.  Owing  to  the  large  quantities 
which  can  be  generated  and  the  high  diffusibility  of  the  gas,  the 
method  is  specially  suitable  where  passages,  corridors,  or  stair- 
cases, with  communicating  rooms,  require  disinfection  at  the 
same  time.  The  drawbacks  against  the  adoption  of  the  method 
by  sanitary  authorities  are  the  weight  of  the  apparatus  and  the 
time  consumed  in  getting  up  steam  and  charging  the  room. 

If  an  attempt  is  made  to  concentrate  aqueous  solutions  of  the 
aldehyde  beyond  40  per  cent,  polymerization  ensues,  and  a 
white  precipitate  of  paraformaldehyde  forms.  This  material 
is  made  into  small  tablets  and  sold  as  "  Paraform  Tablets," 
each  weighing  about  one  gramme.  A  considerable  amount  of 
the  aldehyde  may  be  obtained,  in  a  very  convenient  manner,  by 
means  of  a  spirit  lamp  so  constructed  that  the  hot  and  moist 
products  of  combustion  from  the  lamp  act  upon  these  paraform 
tablets.  Twenty-five  tablets  should  be  employed  to  every 
1,000  cubic  feet  of  space. 

Ligner's  glyco-formal  vaporizing  apparatus  has  furnished 
better  results  in  the  hands  of  experimenters  than  those  obtained 
from  the  use  of  paraform  tablets.  The  apparatus  consists  of  a 
ring  boiler  in  which  steam  is  generated  and  driven  into  a  reser- 
voir containing  a  mixture  of  formic  aldehyde,  glycerine,  and 
water,  which  are  thus  vaporized  and  injected  in  fine  sprays  into 
the  room.     The  apparatus  costs  £4. 

The  gas  is  neutralized  by  ammonia;  and  if  necessary,  the  last 


6i6  Hygiene  and  public  health 

traces  can  be  removed  from  a  room  by  exposing  vessels  containing 
a  little  dilute  solution  of  ammonia.  Goggles,  specially  made  so  as 
to  protect  the  eyes,  may  be  worn  when  the  room  is  unsealed. 

The  Autan  method  of  producing  formaldehyde  is  as  follows: 
For  every  i,ooo  cubic  feet  of  room  space  to  be  disinfected  take 
5  ounces  of  potassium  permanganate  crystals,  and  place  in  a 
metalhc  pail.  Take  |  pint  of  formahn  {^y  to  40  per  cent,  formic 
aldehyde)  and  pour  over  the  permanganate  crystals.  After  a 
few  seconds  chemical  action  takes  place  between  the  perman- 
ganate and  about  one-fifth  of  the  formaldehyde,  which  produces 
heat  sufficient  to  evaporate  nearly  all  the  remainder.  The 
room  must  be  closed  and  sealed  in  the  ordinary  way,  and  kept 
closed  for  six  hours.  Where  formahn  is  not  available,  100  para- 
form  tablets  (i  gramme  each)  may  be  taken,  crushed  into  a 
powder,  placed  in  a  pint  of  hot  water,  which  is  rapidly  brought 
to  boiling  point,  and  used  as  if  it  were  liquid  formahn.  Double 
the  amount  of  potassium  permanganate  should  be  used — namely, 
10  ounces,  instead  of  5  ounces,  per  1,000  cubic  feet.  In  all  cases 
the  amount  of  the  permanganate  needed  is  exactly  half  the 
weight  of  the  hquid  to  be  added.  As  the  mixture  is  hable  to 
froth  over  and  escape  from  the  container,  and  thus  lead  to  the 
injury  of  carpets,  it  is  necessary  to  use  a  large  and  deep  container. 

Sulphurous  Acid  (SOg)  is  a  gas  with  a  density  about  double 
that  of  the  atmosphere,  and  which  therefore  diffuses  badly.  It 
has  a  slight  bleaching  action,  which  is  not  sufficient,  however,  to 
militate  against  its  use.  In  association  with  moisture  it  has 
marked  disinfectant  powers,  a  5  per  cent,  solution  killing  the 
spores  of  Bacillus  anthracis,  and  a  i  per  cent,  solution  killing  non- 
spore-bearing  bacteria,  within  twenty-four  hours,  according  to 
Koch;  but  used  in  the  gaseous  form  it  is  little  more  than  anti- 
septic. Like  other  acids,  sulphurous  acid  absorbs  ammonia, 
compound  ammonias,  and  organic  bases  (ptomaines,  etc.);  it 
decomposes  sulphides  and  sulphuretted  hydrogen,  and  reduces 
or  enters  into  combination  with  organic  matter;  it  also  probably 
exerts  a  direct  toxic  effect  on  bacteria. 

The  old  process  of  disinfecting  a  room  by  sulphurous  acid  is 
rapidly  going  out  of  use,  now  that  equally  convenient  and  more 
efficient  methods  are  available.  The  former  very  general 
practice  admitted  of  division  into  two  stages: 

I  The  charging  of  the  atmosphere  for  from  six  to  twenty-four 
hours  with  from  i  to  2  per  cent,  of  the  gas. 


DISINFECTION  617 

2.  A  subsequent  thorough  aeration  of  the  room  for  several 
liours — -an  essential  feature  of  this  method. 

The  gas  was  generated  and  employed  as  follows: 

1.  Rolled  sulphur  was  broken  up  into  pieces  of  about  the  size 
of  a  marble,  placed  in  an  iron  vessel,  and  then  moistened  with  a 
little  spirit  and  ignited.  At  least  2  pounds  of  sulphur  was  advo- 
cated for  every  i,ooo  cubic  feet  of  space,  about  2  per  cent,  of 
sulphurous  acid  being  thereby  furnished  to  the  atmosphere. 
The  fact  that  the  sulphur  did  not  always  burn  out  was  a  drawback 
to  this  method,  and  it  was  therefore  found  preferable  to  employ- — 

2.  Sulphur  candles,  in  which  the  powdered  sulphur,  mixed 
with  inflammable  material,  was  placed  in  a  small  metal  saucer  and 
lighted  by  a  wick.  These  invariably  burn  out,  and  were  very 
convenient  and  expeditious  in  use. 

3.  An  ordinary  benzohne  lamp  filled  with  carbon  bisulphide;  as 
this  burns,  sulphurous  acid  is  given  off  (CSg  +  202=  COg  +  SOg  +  S) . 

4.  The  gas  can  be  liquefied  by  a  pressure  of  three  atmospheres 
(about  45  pounds  to  the  square  inch),  the  liquefied  gas  being 
passed  into  metal  cyhnders  holding  about  20  ounces.  In  use,  a 
short  piece  of  lead  pipe  with  soldered  end,  which  communicates 
with  the  interior,  is  cut  off,  and  the  cylinder  placed  in  a  basin  with 
the  cut  surface  downwards,  when  the  liquid,  being  reheved  of 
its  pressure,  passes  into  the  gaseous  state.  At  least  two  cylinders 
were  recommended  to  every  1,000  cubic  feet  of  space,  for  the 
contents  of  one  cylinder  would  furnish  slightly  under  i  per  cent. 
The  cost  of  the  cyhnders  is  one  shilhng  each.  There  is  experi- 
mental evidence  that  the  gas  hberated  from  the  hquid  state  is 
not  so  efficient  as  that  obtained  directly  from  the  burning  of 
sulphur. 

Accidents  by  'fire,  when  burning  sulphur  was  used,  have  been 
very  rare,  but  to  guard  against  them  it  is  well  to  support  the 
burning  sulphur  over  a  pail  or  basin  of  water.  This  water, 
especiahy  if  hot,  aids  in  saturating  the  atmosphere,  and  thereby 
increasing  the  disinfecting  power  of  the  gas. 

A  sufficiency  of  moisture  must  be  present  in  the  air  of  the 
room  if  the  SOg  generated  is  to  exert  disinfectant  properties. 
If  the  pan  containing  the  sulphur  to  be  burnt  is  placed  in  a 
shallow  dish  containing  water,  owing  to  the  amount  of  heat 
evolved  in  the  burning,  aqueous  vapour  is  formed  from  the 
water  in  sufficient  amount  to  saturate  the  atmosphere,  and  good 
results  may  be  obtained.     The  saturation  of  the  atmosphere 


6i8 


HYGIENE    AND   PUBLIC   HEALTH 


may  be  assumed  if,  on  the  opening  of  the  room  after  twelve  or 
twenty-four  hours,  condensed  moisture  is  found  on  the  floor, 
walls,  and  surfaces  of  the  apartment.  The  heat  of  the  com- 
bustion of  the  sulphur  causes  the  gas  to  expand,  and  materially 
aids  in  its  diffusion.  The  gas  should  be  evolved  as  high  as 
possible  in  the  room,  and  at  more  than  one  place  unless  the 
room  is  very  small,  so  as  to  aid  diffusion  and  prevent  oxidation 
of  the  gas  before  diffusion  takes  place.  Colonel  Beveridge, 
R.A.M.C,  who  has  made  experiments  on  sulphur  fumigation, 
recommends  that  3  pounds  of  sulphur  should  be  burned  for 
every  1,000  cubic  feet  of  space.  This  amount  of  sulphur,  which 
theoretically  produces  35  per  cent,  of  SOg  in  the  air,  was  found 
in  all  cases  to  be  effective  in  destroying  cultures  of  different 
organisms  exposed  at  the  level  of  the  floor  or  ceiling  after  twenty- 
four  hours'  exposure.  Colonel  Beveridge  estimates  that  five 
cylinders  of  compressed  SOg  (hquefied),  each  containing  20 
ounces,  would  be  required  to  produce  a  percentage  of  SOg  equal 
to  that  evolved  by  burning  3  pounds  of  sulphur.  The  gas 
liberated  in  this  manner  from  tins  of  liquefied  gas  does  not 
diffuse  nearly  so  well  as  the  gas  given  off  by  burning  sulphur, 
and  unless  the  air  of  the  room  is  previously  moistened  by  steam 
or  other  means,  the  requisite  amount  of  aqueous  vapour  is  not 
present  to  enable  the  liberated  gas  to  exert  its  disinfectant 
properties. 

Sulphurous  acid  gas  is  very  useful  for  the  purpose  of  destroying 
vermin,  and  in  this  respect  it  is  far  mox-e  powerful  than  formic 
aldehyde. 

The  gas  is  so  irrespirable  that  it  is  often  impossible  to  enter 
and  unseal  the  room  containing  it.  A  wet  towel,  moistened  with 
washing  soda,  and  placed  over  the  mouth,  will  always  enable  the 
operator  to  enter.  As  bronze,  gilt,  and  copper  surfaces  are 
tarnished  by  the  sulphur  fumes,  these  should,  where  detachable, 
be  wiped  with  i  per  cent,  carbolic  and  placed  just  outside  the 
room  prior  to  the  liberation  of  the  sulphurous  acid. 

Chlorine  (CI).— This  gas  has  most  of  the  defects  of  sulphurous 
acid;  it  is  a  very  irritant  and  heavy  gas,  which  diffuses  badly, 
and  moisture  is  essential  to  its  disinfectant  action.  Compared 
with  sulphurous  acid,  it  is  a  heavier  gas,  possessing  greater  bleach- 
ing properties,  and  somewhat  more  irritant;  it  is  less  convenient 
in  use  and  more  expensive.  On  the  other  hand,  when  present 
to  the  extent  of  i  per  cent,  in  the  atmosphere,  its  disinfectant 


DISINFECTION  619 

power  considerably  exceeds   that  of  a  similar  strength  of  sul- 
phurous acid. 

The  disinfectant  and  deodorant  properties  of  tlie  gas  depend 
upon  its  affinity  for  hydrogen.  Thus,  in  the  presence  of 
moisture,  and  especially  in  daylight,  it  releases  nascent  oxygen 
(Clg  +  HgO^  2HCl-i-0),whicli  burns  up  organic  matter,  including 
bacteria.     It  decomposes  sulphuretted  hydrogen 

(CU  +  SH2-2HCI  +  S), 

and  also  ammonia 

(3CU  +  8NH3=  6NH4CI  +  No). 

It  is  usually  produced  by  the  action  of  sulphuric  or  hydro- 
chloric acid  on  bleaching  powder — 

(CaCl^O  +  2HCI -  CaCl2  +  H2O  +  CI2). 

It  is  advisable  to  use  2  pounds  of  bleaching  powder  and  about 
I  pound  of  the  commercial  acid  for  every  1,000  cubic  feet  of 
space.  The  mixture  should  be  divided  into  several  parts, 
because  of  its  bulk  and  to  ensure  distribution  of  the  gas,  and 
placed  as  high  in  the  room  as  practicable.  Some  experiments 
indicate  the  necessity  of  using  much  larger  quantities  of  the 
bleaching  powder  for  the  more  resistant  infections.  The  powder 
contains  about  35  per  cent,  of  available  chlorine,  and  it  must 
be  kept  dry. 

All  metal  fittings  and  articles  of  silk,  etc.,  should  be  removed 
beforehand;  and  if  great  difficulty  is  experienced  in  entering 
the  room  for  the  purpose  of  unsealing,  the  operator  should  first 
saturate  a  towel  with  weak  ammonia  solution  and  place  it  over 
his  mouth. 

Bromine  (Br)  is  a  heavy  gas,  more  irritating  than  chlorine, 
more  destructive  to  articles  exposed  to  it,  and  also  more  expen- 
sive. It  is  readily  given  off  from  the  volatile  fluid  known  as 
"  liquid  bromine."  As  with  chlorine,  the  presence  of  moisture 
is  essential  to  the  disinfecting  action  of  the  gas. 

Iodine  (I)  is  a  heavy  gas  some  eight  times  heavier  than  air, 
and  more  than  three  times  as  heavy  as  chlorine.  This  circum- 
stance, added  to  the  fact  that  it  stains  exposed  articles  and  is  not 
a  powerful  germicide,  excludes  iodine  from  the  list  of  serviceable 
gaseous  disinfectants. 

Hydrochloric  Acid  (HCl)  fumigation  has  been  advocated. 
Like  other  acids,  it  has  marked  disinfectant  properties,  which 


620  HYGIENE   AND  PUBLIC  HEALTH 

are  doubtless  mainly  due  to  the  circumstance  that  any  marked 
acidity  is  inimical  to  germ  life. 

Nitrous  Acid  (HNOg). — Nitrous  acid  acts  as  an  oxidizer  owing 
to  the  circumstance  that  it  readily  parts  with  oxygen  to  oxi- 
dizable  matter  and  becomes  nitric  oxide  (NO).  This  gas  com- 
bines with  the  oxygen  in  the  atmosphere  (2NO  +  02=  2NO2), 
and  thus  serves  as  a  carrier  of  oxygen  to  oxidizable  matter. 
Nitrous  acid,  therefore,  remains  constantly  active  and  is  not  used 
up  like  chlorine,  over  which  it  also  possesses  the  additional 
advantage  that  it  does  not  destroy  organic  colouring  matters. 
But  the  reddish  fumes  of  nitric  peroxide  (NOg)  are  very  irritating, 
and  their  disinfecting  powers  are  inferior  to  those  of  chlorine. 
For  every  1,000  cubic  feet  of  space  at  least  3  ounces  of  nitric 
acid  should  be  mixed  with  an  equal  volume  of  water,  and  the 
mixture  poured  upon  i  ounce  of  copper  shavings  placed  in  an  old 
jar  or  basin — 

3Cu  +  8HN03=  3Cu(N03)2  +  2NO  +  4H2O. 

Vaporized  Phenol  (CgHgO). — Although  it  is  claimed  by  some 
that  the  use  of  this  agent  succeeds  well  in  practice,  such  large 
quantities  have  to  be  employed  that  the  odour  which  remains 
after  use  is  extremely  persistent.  The  phenol,  placed  in  a  bottle- 
shaped  metal  receiver,  may  be  vaporized  by  means  of  an  iron  rod 
made  red  hot,  which  is  placed  inside  the  receiver  and  allowed  to 
remain  there.     A  pint  of  phenol  can  be  vaporized  in  this  way. 

Solid  Disinfectants. 

These  can  only  be  conveniently  and  effectually  employed  as 
deodorants  in  the  form  of  powders. 

Powders  are  made  containing  phenols,  sulphurous  acid,  etc., 
but  they  all  lose  strength  on  keeping. 

Carbolic  Powders. — The  "  vehicle  "  for  the  carbolic  acid  is 
frequently  lime,  which  is  often  in  very  great  excess.  There  is  a 
resulting  formation  of  carbolate  of  lime,  and  the  powder  soon 
becomes  practically  inert,  for  the  reason  that  it  contains  little  or 
no  available  carbolic  acid.  The  best  class  of  carbolic  powders 
are  warranted  to  contain  at  least  15  per  cent,  of  phenols,  silicious 
matter,  not  lime,  being  used  as  their  basis  ("  carbolized  silicate 
powders  "),  or  absorbent  wood  fibre,  or  peat  ("  carbolized  peat- 
powders  ").  All  such  powders  are  liable  to  lose  from  i  to  2  per 
cent,  of  carbolic  acid  by  volatilization. 


DISINFECTION  62 1 

Slaked  Lime  is  a  good  deodorant,  as  it  absorbs  sulphuretted 
hydrogen  and  most  organic  vapours.  Like  bleaching  powder,  it 
exerts  a  caustic  action,  and  attacks  metals.  Bleaching  powder 
(chloride  of  lime)  deposits  about  40  per  cent,  of  lime,  and  should 
not,  therefore,  be  put  down  drains. 

A  mixture  of  equal  parts  of  "  Sanitas  Powder  "  and  lime  is  a 
good  deodorant,  which  of  itself  gives  off  no  unpleasant  odour. 

Carbon  condenses  gases  in  its  pores,  and  oxidizes  them  by 
means  of  the  condensed  oxygen  therein  contained.  Vegetable 
charcoal  is  a  better  deodorant  than  animal,  but  both  forms  should 
be  only  employed  when  freshly  prepared  and  dry. 

Ordinary  Soap  possesses  marked  disinfecting  properties.  There 
is  little  or  no  advantage  in  using  soaps  impregnated  with  small 
quantities  of  disinfectants. 

Room  Disinfection. 

Wearing  apparel  and  bedding  should  be  steam  disinfected; 
and  if  carpets,  curtains,  rugs,  and  upholstered  articles  were  not 
removed  when  the  sick-room  was  prepared  for  the  patient,  these 
should  also  be  set  aside  for  steam  disinfection.  Thus  the  disin- 
fection of  the  room  is  practically  one  of  surface  disinfection  only, 
for  no  gas  or  vapour,  employed  at  the  current  temperature  and 
pressure,  possesses  powers  of  penetration  to  any  valuable  degree. 

To  be  satisfactory  in  practice,  methods  of  room  disinfection 
must  be  efficient  but  must  not  injure  the  articles  exposed.  The 
facihty  of  application  and  the  cost  are  also  important  considera- 
tions. 

There  are  three  well-known  methods  of  disinfecting  the  exposed 
surfaces  in  rooms,  involving: — 

1.  The  use  of  sprays  or  atomizers,  by  which  the  disinfectant 
(in  solution)  can  be  applied  directly  in  the  form  of  a  very  fine 
spray  to  the  surfaces  of  the  room. 

2.  The  washing  of  all  surfaces  with  a  solution  of  the  disinfec- 
tant, or  the  rubbing  down  of  such  surfaces  with  breadcrumbs. 

3.  Fumigation,  in  which  the  air  is  charged  with  the  dis- 
infectant in  the  form  of  a  gas  or  vapour,  for  a  period  of  from 
six  to  twenty-four  hours.  In  this  method  the  room  should  be, 
as  far  as  possible,  hermetically  sealed — the  windows  closed  and 
chinks  pasted  over  with  paper,  the  chimney  outlet  closed  up, 
and  the  door  crevices  and  keyhole  carefully  pasted  over. 
Before  the  room  is  again  occupied  all  the  fiat  surfaces  of  the 


622  HYGIENE   AND    PUBLIC   HEALTH 

room  upon  which  dust  can  settle  should  be  washed  down  with 
some  disinfectant  solution. 

In  the  case  of  schools  and  hospitals,  the  skirting  and  floor 
boards  should  be  removed  and  washed,  and  all  ventilators  should 
be  swept  out  and  disinfected. 

4.  It  is  advisable  in  most  cases  to  strip  the  wall  papers  and 
limewhite  the  ceiling  as  a  further  precaution. 

After  the  room  has  been  dealt  with,  the  bedding,  clothes,  etc., 
should  be  placed  within  canvas  bags,  which  should  be  damped 
outside  with  water,  and  then  taken  to  the  van  for  removal  to  the 
disinfecting  station  for  steam  disinfection.  The  moistening  of 
the  bag  is  a  precaution  against  the  dislodgment  and  escape  of 
bacteria  from  it  during  the  removal  of  the  articles  from  the  room, 
through  the  house,  and  to  the  station. 

As  mistakes  sometimes  happen,  it  is  necessary  to  make  out  a 
list  of  the  articles  removed  from  each  house,  and  to  obtain  the 
signature  of  some  responsible  person  to  this  list.  The  use  of 
canvas  bags,  which  can  be  placed  with  their  contents  direct  into 
the  stove,  reduces  the  possibility  of  the  mixing  of  articles  from 
different  houses,  and  obviates  the  necessity  of  the  man  at  the 
station  handling  the  infected  articles.  Any  articles,  however, 
which  are  stained,  and  require  to  have  the  stains  removed  before 
being  placed  in  the  stove,  would  be  overlooked  unless  a  special 
bundle  is  made  of  them;  and  books,  leather  articles,  feathers 
and  furs,  which  are  injured  by  steam  disinfection,  must  be 
separately  collected  together. 

The  individual  engaged  in  })reparing  a  room  for  disinfection 
should  always  wear  overalls,  which  shoiild  be  afterwards  left 
behind  in  the  room,  and  removed  with  the  other  articles  for  steam 
disinfection.  This  precaution  diminishes  the  risk  of  the  infection 
being  conveyed  from  the  sick-room,  and  when  the  disinfection  is 
jicrformed  by  the  sanitary  authority  the  precaution  serves  as  a 
useful  object-lesson  to  the  people. 

A  great  deal  has  been  claimed  for  the  spray  method  of  disin- 
fection in  France,  where  it  is  the  official  one. 

The  efficiency  of  a  good  sprayer  must  depend  on  its  ability  to 
deliver  the  liquid  in  the  most  finely  divided  state  possible,  for 
the  more  this  requirement  is  met,  the  more  uniform  will  be  the 
distribution  of  the  disinfectant.  The  Equifex  sprayer  consists 
of  a  metal  reservoir,  which  holds  the  disinfectant,  and  is  lined 
with  ebonite,  so  that  the  metal  is  not  attacked.     The  fluid  is 


DISINFECTION  623 

driven  through  a  spray  nozzle  by  means  of  a  hand  pump,  wliich 
forces  air  into  the  reservoir.  An  extremely  fine  spray,  at  a  velocity 
sufficient  to  ensure  a  slight  degree  of  penetration,  is  made  to 
issue  from  the  end  of  a  metal  tube  of  such  a  length  that  it  can  be 
held  close  to  all  the  surfaces  to  be  treated.  The  cost  is  from  £S 
to  £ib. 

The  spraying  process  must  be  carried  out  in  the  most  comjilcte 
manner,  inch  by  inch,  over  all  the  surfaces  it  is  intended  to 
disinfect.  It  is  calculated  that  to  efficiently  disinfect  800  square 
feet  of  wall  space  two  hours'  spraying  is  required. 

Lumley's  "  Invicta  "  spray  requires  no  pumping  when  at 
work,  the  disinfecting  solution  in  the  tank  of  the  apparatus 
being  brought  under  an  air  pressure  of  ^5  pounds  to  the  square 
inch,  which  causes  the  spraying.  This  is  a  much  cheaper  form 
of  spray  producer  than  the  Equifex. 

The  disinfecting  solutions  to  be  preferred  in  spraying  are: 
Perchloride  of  mercury,  formic  aldehyde,  "  Chinosol,"  or  sodium 
hypochlorite.  The  operation  of  disinfecting  a  small  room 
occupies  one  hour. 

Washing  and  rubbing  methods  appear  to  be  efficient.  All  the 
horizontal  surfaces  of  a  room  may  be  washed  down,  or  coated 
with  disinfectant  by  means  of  a  large  paint  brush,  and  the 
vertical  surfaces  may  be  wiped  and  stroked  with  a  rag  moistened 
with  the  disinfectant.  When  a  brush  is  employed,  two  coats  of 
the  disinfectant  should  be  put  on,  one  with  vertical  strokes  and 
the  other  with  horizontal,  to  ensure  that  the  disinfectant  reaches 
all  the  crevices.  The  German  official  method  is  to  rub  down 
the  walls  with  bread — ordinary  German  loaves,  forty-eight  hours 
old,  being  employed,  cut  into  pieces  6  inches  square,  with  the 
crust  at  the  back  to  afford  a  firm  hold.  The  crumbs  having 
been  swept  up  and  burned,  the  walls  and  ceiHng  are  thoroughly 
sprinkled  with  carbolic  solution,  and  the  floors  and  furniture 
are  washed  with  this  solution. 

An  advantage  which  is  claimed  for  gaseous  disinfectants  is 
that  their  use  necessitates,  before  the  room  can  be  reoccupied,  a 
thorough  exposure  to  fresh  air  for  several  hours — itself  a  useful 
adjunct  to  disinfection. 

While  the  room  is  occupied  by  an  infectious  patient,  it  is  a 
very  general  custom  to  hang  a  sheet  outside  the  door,  and  to 
keep  this  sheet  constantly  moistened  with  disinfectant.  There 
is.  a  tendency  to  regard  the  practice  as  useless,  but  its  retention 


624  HYGIENE    AND    PUBLIC    HEALTH 

is  certainly  to  be  advocated.  Although  such  a  sheet  cannot 
present  an  impassable  barrier  to  the  passage  of  infection,  it  must 
tend  to  limit  the  infection ;  and  its  presence  serves  as  a  warning 
to  all,  and  an  object-lesson  of  the  constant  necessity  for  pre- 
caution. 

The  infectious  sick-room  should  be  kept  clean  by  means  of 
damp  sweeping  and  dusting.  It  has  been  demonstrated  that 
minute  drops  of  infected  moisture  may  be  sprayed  into  the  room 
by  a  patient  coughing,  sneezing,  or  even  speaking;  and  that 
such  drops  may  be  scattered  to  a  distance  of  4  feet  from  the 
patient. 

Books.— Books,  leathern  articles,  furs,  and  feathers  liable  to 
injury  by  being  placed  in  a  hot  air  stove  may  be  disinfected  in  a 
small  compartment  in  which  formic  aldehyde  vapours,  in  sufficient 
quantity  to  furnish  3  per  cent,  to  the  atmosphere,  are  generated. 

The  compartment  is  then  sealed  for  three  or  four  hours.  In  the 
ceiling  of  the  compartment  several  lines  of  wire  are  loosely  fixed, 
so  that  the  books  can  be  suspended  by  their  covers,  the  pages 
being  open,  fan-shape,  to  admit  the  disinfectant;  or  the  articles 
may  be  placed  upon  perforated  shelves  arranged  above  the 
apparatus  from  which  the  formic  aldehyde  is  being  liberated. 
It  does  not  appear  that  books  harbour  infection  except  when  they 
are  old  and  soiled. 

Dead  Bodies  should  be  wrapped  in  a  sheet  soaked  in  "  Izal  " 
(2  per  cent.),  carbolic  acid  (5  per  cent.),  perchloride  of  mercury 
(i  in  500),  formic  aldehyde  (i  per  cent.),  or  other  disinfectants 
of  equal  strength.  Cremation  is  specially  desirable  in  the  case 
of  infectious  bodies. 

GuLLEYS  may  be  sprinkled  over  with  a  good  carboHc  powder, 
or  with  a  mixture  of  equal  parts  of  "  Sanitas  Powder  "  and  lime. 
Bleaching  powder  has  too  unpleasant  an  odour,  and  it  badly 
corrodes  the  metal  grids. 

Stools,  etc. — To  disinfect  enteric  fever  stools,  cholera  evacua- 
tions, tubercular  sputa,  and  other  discharges  from  the  infectious 
sick,  either  Hquid  disinfectants,  boiling,  or  cremation  must  be 
resorted  to.  The  following  liquid  disinfectants  may  be  employed : 
Acid  solution  of  corrosive  sublimate  (i  in  500)  coloured  blue  with 
aniline.  Preparations  containing  carbolic  or  cresylic  acid  (10  per 
cent.),  or  four  tablespoonfuls  of  the  acids  to  i  pint  of  water. 
Solution  of  sulphate  of  copper  or  ferrous  sulphate  (10  per  cent.). 
Solution  of  formic  aldehyde  (4  per  cent.).     Bleaching  powder 


DISINFECTION  625 

solution  acidified  (4  per  cent.).  All  solid  stools  should  be  broken 
up  with  a  piece  of  stick  and  thoroughly  mixed  with  the  disinfect- 
ant. The  agent  must  be  allowed  to  remain  in  contact  with  the 
infected  material  for  at  least  half  an  hour;  and  all  disinfectant 
solutions  must  be  added  to  the  matter  to  be  disinfected  in  such 
quantities  that  they  are  present  in  the  whole  mixture  to  the  re- 
quired extent,  as  indicated  above.  Even  then,  some  of  the 
excreta  may  escape  disinfection.  Sputum  is  disinfected  with 
great  difficulty  by  means  of  hquid  disinfectants;  and  either 
burning  or  steam  for  20  minutes  should  be  employed  in  preference 
to  other  methods. 

Enteric  and  cholera  stools  are  preferably  disinfected  by  the 
following  means: — ■ 

Boiling  for  half  an  hour  under  steam  pressure ;  boiling  for  half 
an  hour  with  i  in  20  carbolic  acid  solution;  mixing  with  a  rela- 
tively large  amount  of  straw  or  sawdust,  then  saturating  with 
paraffin  or  petroleum  and  burning;  mixing  with  coal  dust  and 
ashes,  and  burning  in  an  incinerator  with  a  high  flue. 

The  impossibihty  of  disinfecting  or  sterilizing  large  volumes  of 
sewage  or  night  soil  by  the  use  of  chemical  reagents,  unless  apphed 
in  enormous  and  ruinous  quantities,  need  hardly  be  insisted  on. 
Small  quantities  of  chemical  reagents  may  be  very  efficient 
deodorizers,  for  offensive  smells  are  thus  concealed  or  destroyed; 
but  the  removal  of  offensiveness  must  never  be  regarded  as 
equivalent  to  destruction  of  infection. 

Hands.— The  disinfection  of  the  hands  is  a  matter  of  great 
difficulty,  and  it  is,  therefore,  wise  to  protect  the  hands,  where 
possible,  by  wearing  thin  india-rubber  gloves.  The  best  practical 
means  of  deahng  with  infected  hands  is  to  scrub  them  thoroughly 
with  soap  and  hot  water,  using  a  nail  brush  assiduously,  then  to 
scrub  and  soak  them  in  absolute  alcohol  for  five  minutes,  and  then 
to  steep  them  for  five  minutes  in  a  solution  containing  i  in 
500  of  the  iodide  of  mercury  dissolved  in  the  iodide  of  potassium. 
It  is  useful  to  have  a  little  alcohol  added  to  the  disinfectant 
solution. 

Ships.— Clayton  gas  is  a  useful  means  of  disinfecting  ships. 
The  Clayton  apparatus  consists  of  an  iron  furnace  specially 
constructed  to  burn  sulphur  in  a  current  of  air,  a  flexible  rubber 
hose  conveying  the  gas  from  the  apparatus  to  any  part  of  the 
ship.  The  gas  contains  about  15  per  cent,  of  sulphurous  acid 
together  with  some  sulphuric  acid.     It  is  usually  recommended 

40 


626  Hygiene  aNd  public  Health 

that  one  pound  of  sulphur  is  required  for  the  disinfection  of  250 
cubic  feet  of  space,  so  that  there  may  be  from  three  to  five  per 
cent,  of  the  gas  in  the  atmosphere  of  the  compartment  to  be 
disinfected.  There  is  testimony  to  the  fact  that  all  rats  and 
insects  in  a  ship  are  destroyed  in  two  hours  in  these  circum- 
stances; but,  although  the  method  is  valuable  for  cabins  and 
empty  holds,  owing  to  the  rapid  absorption  of  sulphur  di-oxide 
by  most  articles  of  cargo  its  use  on  this  account  for  laden  vessels 
is  restricted.  Pathogenic  bacteria  require  a  somewhat  larger 
percentage  of  the  gas  and  an  exposure  of  several  hours;  and 
sporing  specific  organisms  (such  as  Anthrax)  cannot  be  thus 
disinfected.  Although  the  application  of  the  process  is  subject 
to  considerable  limitations,  it  is  better  on  the  whole  than  either 
of  the  processes  which  have  been  suggested  involving  the  use  of 
carbonic  acid  or  carbon  monoxide;  for,  with  these  disinfectants, 
rats,  etc.,  die  in  their  hiding-places,  whereas  they  more  often 
come  out  into  the  open  to  die,  when  exposed  to  sulphurous  acid. 

Fleas  and  Bugs. — The  body-louse  {Pediculus  vestimenti) 
closely  resembles  the  head-louse.  It  lives  in  the  creases  of  the 
garments  worn  next  the  skin,  and,  after  biting,  sucks  blood  from 
the  skin.  The  female  deposits  its  ova  on  the  garments  it  infects, 
and  the  embryos  are  hatched  out  in  about  a  week.  Both  head 
and  body  lice  are  transferred  from  person  to  person  by  close 
contact  or  by  the  wearing  of  infected  caps  or  clothes. 

The  common  flea  {Pulex  irritans)  takes  nearly  four  weeks  to 
develop  from  the  eg^.  The  female  deposits  its  barrel-shaped 
white  eggs  in  the  cracks  of  furniture,  walls,  or  floors;  and  flea 
larvae  have  been  reared  in  the  sweepings  of  the  carpets. 

Under  the  Cleansing  of  Persons  Act  of  1897,  Sanitary  Authori- 
ties may  make  provision  for  freeing  persons  from  vermin,  and 
for  this  purpose  arrangements  are  made  whereby  the  verminous 
individual  may  receive  a  bath  while  the  clothing  is  being  steam 
disinfected.  It  is  often  found  necessary  to  deal  with  the  person's 
home  on  the  same  day  as  that  on  which  the  person  is  cleansed. 
Again,  under  the  Children's  Act  of  1908  power  is  given  to 
obtain  the  cleansing  of  verminous  school-children.  It  is  diffi- 
cult to  speak  too  highly  of  the  value  of  this  work,  and  of  the 
good  services  which  school-nurses  perform  in  respect  to  ver- 
minous children;  for  not  only  are  vermin  dangerous  and  de- 
moralizing, but  by  robbing  children  of  rest  and  sleep  they 
render  many  mentally  unfit  to  properly  respond  to  educational 


DISINFECTION  627 

influences.     The  preventive  measures  may  be  briefly  defined  as 
follows : — 

In  the  first  place  it  is  desirable  that  the  homes  of  the  poorer 
class  should  be  made  as  vermin-proof  as  possible,  by  avoiding 
wooden  skirtings,  mouldings,  etc.,  and  even  wall-papers,  unless 
these  are  sized  and  varnished.  It  cannot  be  too  strongly  im- 
pressed that  a  verminous  house  is  a  dirty  house,  and  that  one 
of  the  greatest  preventive  measures  against  lice  and  bugs  is 
cleanliness.  Verminous  bedding  and  clothing  can  only  be 
satisfactorily  dealt  with  by  steam  disinfection.  The  infected 
rooms  may  then  be  fumigated  with  sulphur,  three  pounds  of 
sulphur  being  burnt  to  every  1,000  cubic  feet  of  space.  Subse- 
quently to  this  the  rooms  should  be  thoroughly  washed,  and  iron 
bedsteads  and  wire-mattresses,  etc.,  exposed  to  a  plumber's 
blow-lamp  or  brushed  over  with  a  strong  solution  of  the  per- 
chloride  of  mercury  and  rectified  spirit  or  petroleum ;  the  raking 
of  cracks  in  the  floor  boards  and  the  dusting  in  of  dry  powdered 
lime  is  also  of  service,  and  old  wall-papers  must  generally  be 
removed.  Of  the  odorous  substances  which  discourage  fleas 
and  bugs,  the  essence  of  thyme  appears  to  be  the  most  efficacious. 

The  Disposal  of  the  Dead. 

Cremation  is  the  most  sanitary  method  of  disposal  of  the  dead. 
The  method  is  of  great  antiquity,  and  was  commonly  employed 
by  the  ancient  Greeks  and  Romans.  The  body  can  by  this 
method  be  reduced,  within  the  space  of  two  hours,  to  a  small 
quantity  of  odourless  ash,  which  can,  if  the  relatives  of  the 
deceased  so  desire,  be  preserved  in  sealed  urns  in  a  columbarium 
adjacent  to  the  crematorium.  Cremation,  too,  prevents  the 
pollution  of  the  ground — a  pollution  which  is  of  a  dangerous 
character  when  the  bodies  of  those  who  have  died  of  infectious 
diseases  are  interred. 

This  method  of  disposal  of  the  dead  is  making  progress  in  this 
and  other  countries,  and  several  crematoria  have  been  provided 
in  Great  Britain  during  recent  years.  Temperatures  of  i,8oo°- 
2,000°  F.  are  now  attained  in  the  furnaces;  and  the  heated  gases 
from  the  furnace  perform  their  work  in  under  two  hours. 

The  main  objections  which  are  raised  against  cremation  at  the 
present  day  are  based  on  sentimental  and  religious  grounds, 
which  time  and  education  will  remove,  for  the  ultimate  effects 
of  cremation  and  earth  burial  are  precisely  the  same.     In  earth 


628  HYGIENE    AND   PUBLIC   HEALTH 

burial  the  ultimate  resolution  of  the  body  into  its  component 
elements  may  take  a  year  or  many  years  to  accomplish,  whereas 
by  incineration  the  same  products  are  formed  in  as  many 
hours.  These  products  are  largely  gaseous,  and  whereas  in 
cremation  special  provision  is  made  to  completely  burn  them  up 
without  offence,  in  earth  burial  they  necessarily  pollute  the  soil, 
and  escape  into  the  general  atmosphere.  There  are  only  two 
real  objections  which  can  be  raised  against  cremation: — namely, 
the  cost  of  the  process,  and  the  fact  that  the  complete  destruction 
of  the  body  involves  also  the  destruction  of  evidence  of  certain 
crimes.  As  regards  the  first  objection,  the  original  cost  of  erection 
of  a  crematorium  is  considerable,  and  the  working  expenses  are 
high;  but,  where  there  is  a  crematorium  within  easy  access  by 
road  or  rail,  cremation  can  now  be  carried  out  at  about  the  same 
cost  as  earth  burial.  To  meet  the  second  objection.  State 
officials  could  be  appointed,  as  in  France  and  Germany,  to 
inquire  into  and  verify  the  death  certificates;  and,  as  a  means 
to  the  same  end,  the  English  Cremation  Society  has  drawn  up  a 
code  of  very  stringent  rules  (including  two  independent  certifi- 
cates of  death)  which  mast  be  complied  with  before  a  body  can 
be  cremated. 

Earth  Burial. — This  method  causes  pollution  of  both  soil  and 
air,  and  should  be  discontinued  within  the  borders  or  in  the  near 
neighbourhood  of  towns  and  thickly  populated  districts.  As  the 
old  burial  grounds  in  towns  become  filled  up  they  have  to  be 
closed,  and  these  can  then  be  converted  into  open  spaces  and 
garden  recreation  grounds.  Burial  sites  at  a  distance  from  the 
town  must  then  be  provided,  at  great  cost  and  much  incon- 
venience to  the  ratepayers. 

It  is  necessary,  in  order  to  carry  out  earth  burial  under  the 
most  favourable  conditions,  to  provide  from  a  quarter  to  half  an 
acre  of  land  to  every  i,ooo  of  the  population  for  some  fourteen 
years,  according  to  the  suitability  of  the  soil  for  the  purposes  of 
interment. 

A  sandy  and  calcareous  loam  is  the  best  soil  for  a  graveyard; 
a  stiff  clay,  which  retards  dissolution,  is  the  worst.  In  clay  sites, 
moreover,  the  ground  is  liable  to  crack  in  very  dry  weather, 
and  the  gases  of  putrefaction  may  then  find  a  direct  outlet  to 
the  surface  of  the  burial  ground.  Coarse  gravel,  comparatively 
free  from  any  binding  material,  and  broken  rock  are  too  loose 
and  open  to  constitute  good  soils  for  burial  sites;  and  chalk 


DISINFECTION  629 

is  contra-indicated  on  account  of  the  risk  of  fissures  transmitting 
impurities  to  the  air  above  or  to  a  water  supply  below.  An 
isolated  tract  of  ground,  with  good  surface  falls  for  natural 
drainage,  and  having  a  considerable  thickness  of  fine  sand  and 
sandy  loam,  or  sandy  and  loamy  gravel,  resting  upon  a  deep  bed 
of  clay,  would  constitute  an  ideal  site.  The  earth  should  have  a 
depth  of  not  less  than  10  feet,  and  graves  should  never  be  dug 
deeper  than  8  feet  from  the  surface.  In  every  case  a  space  of  at 
least  2  feet  should  intervene  between  the  bottom  of  the  grave 
and  the  surface  of  the  subsoil  water. 

As  at  present  practised,  with  the  use  of  lead  shells  and  strong 
wood  coffins,  the  method  of  earth  burial  preserves  the  bodies  for 
a  very  long  period.  Nothing  whatever  is  gained  by  this  lengthy 
preservation;  and  the  aim  of  rational  earth  burial  should  be  to 
facihtate  the  ultimate  reduction  of  the  body  into  its  component 
elements.  To  this  end,  the  body  should  be  placed  in  an  easily 
perishable  coffin  of  wickerwork  or  of  unprepared  wood,  and  the 
grave  should  not  be  deeper  than  3  to  5  feet  from  the  surface — 
the  earth  being  very  much  more  active  as  a  destructive  and 
purifying  agent  in  the  upper  layers  not  exceeding  5  feet  in 
depth  from  the  surface,  than  it  is  at  greater  depths. 

By  the  use  of  quicklime  in  earth  burial  the  soft  tissues  of  the 
body  are  rapidly  destroyed,  and  the  process  of  decomposition  is 
completed  at  a  comparatively  early  period. 

Other  methods  of  disposing  of  the  dead  are  : — (i)  By  simple 
exposure  to  the  air,  as  practised  by  the  Australian  aborigines; 
{2)  committal  to  the  sea;  (3)  the  exposure  of  the  body  in  the 
sun  and  open  air — the  fleshy  parts  may  be  eaten  by  vultures,  a 
method  followed  by  the  Parsees  of  India  in  their  "  Towers  of 
Silence  ";  (4)  desiccation  or  mummification. 

Embalming  was  commonly  practised  in  ancient  Egypt.  The 
abdominal  viscera  were  extracted  by  incision  on  the  left  side, 
and  the  cavity  was  then  cleansed  with  palm  oil  and  filled  with 
myrrh,  cassia,  and  other  odoriferous  substances.  The  body 
was  ultimately  wrapped  in  very  numerous  layers  of  cloth  and 
sealed  up  hermetically.  In  the  modern  method  of  temporarily 
preserving  bodies,  the  cavities  of  the  chest  and  the  abdomen 
are  emptied  and  washed  with  camphorated  spirit;  the  organs 
are  then  similarly  washed  and  injected  with  some  preservative 
fluid  before  they  are  replaced.  The  vascular  system  is  also  in- 
jected with  a  preservative  fluid,  it  being  a  common  practice  to 


630  HYGIENE    AND    PUBLIC   HEALTH 

inject  into  the  carotid  artery  some  6  to  8  pints  of  a  mixture, 
consisting  of  carbolic  acid  i  part,  glycerine  10  parts,  alcohol 
50  parts,  and  water  40  parts.  The  surface  of  the  body  should  be 
lubricated  with  vaseline  containing  5  per  cent,  of  carbolic  acid, 
and  it  is  advisable  to  fill  the  cavities  of  the  body  with  cotton  wool 
soaked  in  glycerine  containing  5  per  cent,  of  carbohc  acid. 

A  more  recent  method  of  preserving  bodies  is  by  exposure 
for  3  or  4  weeks  to  the  vapour  of  formic  aldehyde  (Rechter's 
method).  Underneath  the  open  wire  shelf,  on  which  the  body 
rests  in  the  sterilizing  chamber,  an  ice  closet  is  placed,  in  order 
to  inhibit  by  cold  the  action  of  the  intestinal  bacteria,  until  the 
formic  aldehyde  vapour  begins  to  produce  a  distinct  antiseptic 
effect. 


CHAPTER  XII 
STATISTICS 

Statistical  Inquiries. 

The  science  of  statistics  consists  in  the  collection  of  individual 
facts,  with  the  view  of  grouping  them  into  different  classes  accord- 
ing to  certain  definite  characters  they  possess.  The  rule  to 
which  attention  must  be  specially  directed,  in  dififerentiating  a 
series  of  facts,  is  that  the  points  of  difference  or  characteristics 
on  which  a  group  is  to  be  formed  should  be  common  to  each 
member  of  that  group,  but  absent  from  the  members  of  all  other 
groups.  The  dividing  character  must  be  constant,  and  must  be 
definite. 

It  does  not  follow  that,  because  in  any  series  of  cases  the 
groups  bear  a  certain  numerical  proportion  to  the  total  number 
of  cases,  these  proportions  will  be  the  same  in  any  subsequent 
series  of  like  cases,  unless  the  numbers  dealt  with  in  the  first 
case  are  infinitely  large. 

The  relative  values  of  two  or  more  series  are  as  the  square 
roots  of  the  number  of  units  of  observation;  and  thus  by  in- 
creasing the  number  of  observations  in  any  inquiry,  the  value  (or 
accuracy)  increases  as  the  square  root  of  the  number. 

The  smaller  the  number  of  individual  facts  on  which  the  groups 
are  founded,  the  greater  is  the  possible  deviation  from  the 
proportions  which  may  be  observed  in  any  subsequent  series 
of  like  facts.  By  Poissoji's  Rule  the  limits  of  error,  or  the  degree 
of  approximation  to  the  truth  of  the  numerical  relations  existing 
between  the  units  or  groups  of  a  series,  may  be  ascertained. 

Let  M=  total  number  of  cases  in  the  series  recorded. 
,,    m=  number  of  cases  in  one  group. 
,,     «=  number  of  cases  in  the  other  group. 

fft  "It 

Then  m  +  i>=M,  and  —   and  -   are  the  proportions  of  each 

M        :\i 

631 


632  HYGIENE    AND   PUBLIC   HEALTH 

part  to  the  whole.     But  on  subsequent  occasions,  with  another 
series  of  like  cases,  the  proportions  may  be 

w  / 2.m.n        w        .  /2.W.W 

^T^L  +  2  V ;  or  ,,—  2  V 

M  M^  M        ^     M^ 

And  the  same  holds  good  with  n  group  of  cases.     The  larger  the 

value  of  M,  the  less  will  be  the  value  of  the  fraction  of  which 

M^  is  the  denominator,  and  consequently  the  smaller  the  Umit 

of  error. 

Example. — 

M  =  100  cases  of  fever. 

m  =    25  cases  which  die. 

M  =    75  cases  which  recover. 

fit 
Then  the  proportion  ^  or  J  of  fatal  cases  may  be  in  other  instances 


,  ,       .   /2X  25  X75 

I-+2  A/  ^^p^  =  0'25  +  0'I225r=0' 

*  V  TOO* 


3725: 

0rJ-2A/  ^   3  -^  =0'25-0'I225  =  0'I275. 

That  is  to  say,  in  100  other  cases  of  the  same  fever,  instead 
of  the  deaths  being  25,  they  may  be  as  many  as  37,  or  as  few 
as  13. 

The  arithmetical  mean  of  a  series  of  figures  is  obtained  by 
adding  together  the  numerical  values  of  the  figures,  and  dividing 
the  total  by  the  number  in  the  series.  This  mean  number  will 
have  a  higher  numerical  value  than  belongs  to  some  of  the 
figures  composing  the  series,  and  a  lower  numerical  value  than 
belongs  to  others.  The  less  the  difference  between  the  mean 
and  the  figures  of  the  series,  the  greater  is  its  value,  and  the 
more  closely  does  it  conform  to  a  true  average.  The  relative 
values  of  two  or  more  similar  series  are  as  the  reciprocals  of  the 

squares  of  the  probable  errors  ;  that  is  as    ,  where  pe  is 

(:Pef 

the  probable  error.  The  probable  error  is  approximately  two- 
thirds  of  the  mean  error,  and  implies  that,  if  the  series  were 
prolonged  indefinitely,  the  error  would  probably  exceed  or  fall 
short  of  this  mean  to  the  proportion  indicated  by  the  figure  of 
the  probable  error.  It  is  obtained  as  follows:  i.  Find  the  mean 
of  the  series  of  observations ;  find  the  mean  of  all  the  observations 
above  the  mean,  and  subtract  the  mean  from  it;  this  gives  the 
mean  error  in  excess.  2.  Find  the  mean  of  all  the  observations 
helow  the  mean,  and  subtract  the  latter  from  the  mean;  this 
gives  the  mean  error  in  deficiency.     Add  the  two  quantities 


STATISTICS  633 

(mean  error  in  excess  and  mean  error  in  deficiency),  and  take 
the  half;  this  is  the  meaji  error. 
The  various  means  are: 

a+b+c+d+e 


The  arithmetical  mean  = 


The  geometrical  mean=  Vab  c  d  e 

5 


The  harmonic  mean=  i      i      i      i      i 

-  +-,+  -+  -+  - 
a     0     c     d     e 


/  a^  +  h^  +  c^  +  d^  +  e^ 


The  quadratic  mean: 

5 

If  the  terms  of  the  series  are  equal,  the  above  means  are  all 
identical.  If  the  terms  are  unequal,  the  quadratic  mean  is  the 
highest,  the  arithmetical  comes  next,  and  then  follow  the 
geometrical  and  harmonic  means. 

The  value  or  reliability  of  an  average  or  arithmetrical  mean, 
when  applied  to  any  one  factor,  is  evidently  dependent  upon  the 
degree  of  approximation  between  the  average  and  the  various 
factors  numerically  expressed.  Thus,  in  two  streets  A  and  B, 
each  containing  20  houses,  the  average  number  of  persons  per 
house  may  be  the  same,  but  the  value  of  the  average  in  its 
applicability  to  any  particular  house  in  either  street  may  be  ver}^ 
different.  Thus,  if  in  street  A  10  houses  have  8  inhabitants, 
6  have  4,  and  4  have  2,  the  average  is  5-6  persons  per  house; 
whilst  in  street  B  i  house  has  7  inhabitants,  10  houses  have  6, 
and  9  houses  have  5,  the  average  again  is  5-6  per  house.  But 
the  value  of  the  average  is,  according  to  biometricians,  in  inverse 
ratio  to  the  standard  deviation,  usually  denoted  y,  which  is 
obtained  by  the  following  mathematical  formula: 

o-^  ^/rh.cix'  +  n^az^  +  n^az^ 
N 
in  which  Wj  n^^,  etc.,  are  the  number  of  factors  having  the  same 
values  or  measurements,  and  a^  a^,  etc.,  are  the  number  of  units 
separating  each  group  value  from  the  mean  value  of  the  whole  N. 
The  standard  deviation  in  the  case  of  street  A  will  be  found 
to  be  2-5,  whilst  in  the  case  of  street  B  it  is  only  o-i8.^ 
1   (A)   a  =    A  /^ox^-4^+6xi-62+4X3-6^_  2.5. 

^  '  \^  20 


(B)  <T  =   .  /ix  i-4-+ioxo-4^  +  9XO-62^ 
V  20 


634  HYGIENE    AND    PUBLIC    HEALTH 

The  factors  in  these  equations  are  obtained  as  follows: 
Taking  street  A,  2-4-=  the  difference  between  8  and  5-6;  and 
1-6  that  between  4  and  5-6;  and  3-6  that  between  2  and  5-6. 

The  two  standard  deviations  above  given  are  comparable, 
because  the  arithmetical  means  coincide.  Two  standard  devia- 
tions without  their  corresponding  means  are  valueless.  If,  for 
example,  the  means  of  two  series  of  numbers  are  15  and  5,  and 
their  standard  deviations  are  2  and  i  respectively,  the  mean  15, 
with  a  standard  deviation  of  2,  is  nearer  to  the  truth  than  the 
mean  5,  which  has  a  standard  deviation  only  half  that  of  the 
former.  If  the  arithmetical  means  do  not  coincide,  then  com- 
parable figures  can  be  obtained  by  dividing  each  standard  devia- 
tion by  its  corresponding  mean  and  multiplying  by  100,  the  result 
obtained  being  called  the  cocjfwient  of  variation.  Thus,  if  we 
compare  streets  A  and  B  with  another  street  C  of  20  houses, 
of  which  10  houses  have  7  inmates,  6  houses  have  6  inmates,  and 
4  houses  have  5  inmates,  the  average  per  house  is  6-3  persons, 
and  the  standard  deviation  is  0-25.     The  coefficients  of  variation 

^^  A  u        ^  n  ^-1  2-5  o-i8  ,  0-25 

01  A,B,and  L  respectively  are  —  x  100,  x  100,  and  — -  x  100, 

5-6  56  6-3 

or  44-6,  3-2,  and  4-0. 

Correlation. — Series  of  phenomena  arc  said  to  be  correlated 
when  certain  values  of  one  phenomena  occur  more  commonly 
with  given  values  of  the  other.  The  correlation  may  be  positive 
or  negative.  If  the  increase  in  the  values  of  one  series  of  pheno- 
mena is  associated  with  an  increase  in  the  other,  the  correlation 
is  positive;  but  if  the  increase  in  the  one  series  is  associated  with 
a  decrease  in  the  other  the  correlation  is  negative.-^  Thus  there 
is  positive  correlation  between  summer  diarrhoea  prevalence  and 
the  temperatures  of  the  air  and  earth,  whilst  there  is  negative 
correlation  between  summer  diarrhoea  and  rainfall.  The  study 
of  correlation  has  for  its  object  the  determination  of  a  quantita- 
tive measure  of  the  degree  of  association  of  the  phenomena 
observed,  it  being  clearly  understood  that  the  correlation  of 
phenomena  in  no  sense  implies  that  they  stand  to  one  another 
in  the  relation  of  cause  and  effect,  but  that  there  is  similar 
association  of  the  variables  composing  the  phenomena.  The 
coefficient  of  correlation,  when  it  is  positive,  is  any  figure  between 
o  and  +  I.      If  the  phenomena  are  identical  in  their  variables, 

1  See  paper  by  Dr.  J.  M.  Troup  and  Mr.  G.  D.  IN'rynard,  on  "  iModern 
Statistical  Methods  "  {Lancet,  May  14,  1910). 


STATISTICS  635 

the  curves  representing  the  variables  will  also  be  identical,  and 

the  coefticient  (r)  is  +  i ;   if  there  is  no  correlation,  then  r=o. 

Similarly  complete  negative  correlation  is  indicated  by  r=  -  i, 

and  all  degrees  of  negative  correlation  lie  between  -  i  and  o. 

The   probable  error  of  a  coefficient  of  correlation   is  usually 

expressed  as — 

^  I — r'" 

0-6745  X 

r=  the  coefficient. 
A^=  the  number  of  cases  dealt  with. 

If  only  a  few  cases  have  been  considered  and  the  coefficient 
is,  say,  only  o-i,  then  it  is  quite  possible  that  really  there  is  no 
correlation  at  all,  as  the  accuracy  is  directly  proportional  to 
the  number  of  cases  under  observation. 

Theory  of  Probability. — The  object  of  the  theory  of  probability 
is  to  obtain  an  accurate  measure  of  the  likelihood  of  the  occur- 
rence of  events  under  conditions  some  of  which  are  known  and 
some  unknown.  Algebraically  the  probability  of  the  occurrence 
of  an  event  is  expressed  by  a  fraction,  the  numerator  of  which 
represents  the  number  of  ways  in  which  the  event  can  happen, 
and  the  denominator  the  sum  of  the  number  of  ways  in  which  it 
can  happen  and  in  which  it  can  fail.^  If  the  sum  of  the  two 
probabilities — -the  event  happening  and  the  event  failing — is 
unity,  the  measure  of  the  probability  may  vary  from  unity  to 
zero — unity  denoting  absolute  certainty  of  the  occurrence,  zero 
absolute  certainty  of  its  non-occurrence. 

Thus,  supposing  that,  on  the  average,  of  men  aged  twenty  to 
thirty-five  years  in  miUtary  service,  who  contract  tubercle  of  the 
lung,  20  per  cent,  recover  and  20  per  cent,  die  whilst  with  the 
colours,  whilst  60  per  cent,  are  invalided  out  of  the  service,  the 
probabiHties  of  recovery  and  of  death  are  equal — namely  i — 
whilst  the  probability  of  being  invalided  is  i;  or,  in  popular 
language,  the  odds  are  5  to  i  each  against  recovery  or  death,  and 
5  to  3  against  being  invalided. 

In  medical,  vital,  and  public  health  statistics,  series  of  pheno- 
mena are  often  claimed  to  be  related  to  one  another,  or  to  stand 
in  relation  to  one  another  as  cause  and  effect,  without  any 
account  being  taken  of  the  possibility  that  the  phenomena  may 
be  chance  distributions  explainable  under  the  theory  of  proba- 
bility. Thus  the  mortality  or  proportion  of  deaths  to  recoveries 
1   "  Modern  Statistical  JNIetliods,"  by  Troup  and  Maynard. 


636  HYGIENE    AND   PUBLIC   HEALTH 

(case-rate)  in  the  course  of  an  epidemic  of  any  disease  may  vary 
with  the  progress  of  the  epidemic,  and  this  might  be  due  to 
variation  in  virulence  of  the  infection,  to  variation  in  resisting 
powers  of  the  individuals  attacked,  or  to  other  special  circum- 
stances affecting  the  locale  or  environment,  but  it  might  in  whole 
or  part  be  a  chance  distribution  calculable  under  the  formulae 
applicable  by  the  theory  of  probability. 

Vital  Statistics. 

The  uses  of  vital  statistics  are  to  obtain  information  as  to 
the  health  of  the  people  and  as  to  the  various  diseases  from  which 
they  suffer;  to  assist  in  the  study  of  the  good  and  evil  conditions 
affecting  them ;  and  to  furnish  the  necessary  data  for  life  assurance. 

To  obtain  the  statistics  of  a  community  which  have  relation 
to  its  public  health,  it  is  necessary' to  have  a  correct  enumeration 
of  the  population,  a  complete  registration  of  births  and  deaths, 
and  a  correct  statement  as  to  the  cause  of  death,  together  with 
the  age  of  every  deceased  person.  The  number  of  births  and 
of  deaths  which  take  place  in  the  course  of  a  year  are  generally 
expressed  in  the  form  of  rates,  i.e.,  so  many  births  or  so  many 
deaths  to  1,000  of  the  population. 

The  first  inquiry,  therefore,  which  becomes  necessary  is  to 
ascertain  for  any  community  the  number  of  those  living  during 
any  year.  The  last  census  returns  give  the  exact  enumeration 
of  the  numbers  living  and  their  ages  at  the  time  the  census  was 
taken.  If  the  population  is  stationary — the  births  equalling  the 
deaths  and  no  emigration  or  immigration  taking  place— the  census 
returns  are  true  for  any  subsequent  year.  In  this  country  the  births 
have,  for  a  great  number  of  years,  exceeded  the  deaths  and  the 
emigrations,  with  the  result  of  a  steady  increase  of  the  population. 

By  the  Law  of  Population,  a  population  increases  in  regular 

geometrical  progression  when  the  births  exceed  the  deaths  and 

the  ratio  of  the  births  and  of  the  deaths  to  the  population  remains 

constant. 

Example. — If  the  birth  rate  of  a  population  numbering  5,000  is  30  per 
1,000,  and  the  death  rate  is  20  per  1,000,  and  these  rates  remain  con.stant 
for  ten  years,  the  annual  rate  of  increase  is  10  per  1,000,  or  0"0i  per  unit; 
i.e.,  one  person  becomes  i-oi  at  the  end  of  the  year,  or  1,000  persons  become 
1,010.  The  population  at  the  end  of  the  tenth  year  (the  last  term  of  the 
series  in  geometrical  progression)  =  5,000  x  i •0110=  5,523  persons.  For 
the  population  at  the  end  of  the  first  year  is  5,000  x  i-oi;  at  the  end 
of  the  second  year  it  is  (5,000  x  i-oi)  x  i'oi=  5,000  x  i-oi-;  at  the  end  of 
the  third  year  it  is  (5,000  x  i-oi^)  x  i'Oi=  5,000  x  i-oi^;  and  at  the  end  of 
the  tenth  year  it  is  5,000  x  i-oi  i". 


STATISTICS  637 

The  population  of  England  and  Wales  in  1843  was  about 
half  the  population  in  1901,  consequently  it  took  58  years  to 
double  itself. 

The  term  "  increment  of  life  "  is  sometimes  employed  to 
denote  the  excess  of  births  over  deaths  in  a  population,  and  if 
the  balance  is  on  the  opposite  side  it  is  sometimes  referred  to 
as  the  "  decrement  of  life." 

Sometimes  the  terms  "  effective  "  and  "  specific  "  are  applied 
to  a  population.  The  "  effective  "  population  is  the  population 
between  the  ages  of  twenty  and  seventy,  and  the  "  specific  " 
population  is  the  number  of  persons  to  each  acre  or  square  mile 
which  is  the  same  thing  as  the  density  of  the  population.  This 
is  more  usefully  stated  as  the  average  number  of  persons  occupy- 
ing a  room. 

In  calculating  birth  rates  or  death  rates  for  any  year,  the 
estimated  population  for  the  middle  of  that  year  must  be  taken 
as  the  basis;  for  it  alone  represents  the  average  number  of 
persons  who  are  living  throughout  that  year.  The  following 
method  is  used  by  the  Registrar-General  for  estimating  from  the 
last  two  census  returns  the  population  of  a  town  or  district  for 
the  middle  of  any  year. 

Example. — Suppose  the  population  of  a  town  by  the  census  of  1891 
is  X,  and  by  the  census  of  1901  is  y,  and  it  is  required  to  know  the  popula- 
tion in  the  middle  of  the  year  1905.  Then  the  log.  y  -log.  ,r=  log.  of  the 
rate  of  increase  for  10  years.  This  divided  by  10  will  give  the  log.  of  the 
rate  of  increase  for  i  year.  From  the  end  of  the  first  quarter  of  1901 
(when  the  census  was  taken)  to  the  middle  of  1905  is  4^  years,  and  there- 
fore the  log.  of  the  population  in  the  middle  of  1905=  log.  of  the  population 
in  1901  +  (4|  X  log.  of  I  year's  increase).  The  number  corresponding  to  this 
logarithm  will  give  the  calculated  population. 

This  method  assumes  that  the  population  of  the  town  is 
increasing  or  decreasing  in  the  same  ratio  since  the  last  census 
as  it  did  between  1891  and  1901.  It  is  here  that  a  fallacy 
may  arise.  Thus  the  population  which  serves  as  the  basis  for 
calculating  the  birth  and  death  rates  in  the  ten  years  inter- 
vening between  any  two  census  returns  is  only  an  estimate, 
and  therefore  only  approximately  true.  The  estimates  of 
population  so  obtained  generally  exhibit  a  considerable  diver- 
gence from  the  actual  truth  in  the  years  most  remote  from 
the  last  census.  Consequently,  statistics  calculated  upon  such 
estimates  are  usually  erroneous.  A  comparison  may  be  made 
between  this  estimate  and  that  arrived  at  by  a  calculation  of 


638  HYGIENE    AND   PUBLIC   HEALTH 

the  number  of  inhabited  houses  in  the  districts,  as  obtained 
from  the  rate  books,  and  the  average  number  of  inhabitants 
in  each,  as  shown  by  the  last  census;  but  this,  again,  is 
only  an  approximation.  The  average  number  of  persons  per 
inhabited  house  may  vary  from  4-5  to  9,  according  to  the  size 
of  the  house  and  the  class  of  property;  according  to  the  census 
of  1901,  it  was  5-19  in  England  and  Wales.  One  individual 
should  be  allowed  to  each  empty  house,  in  order  to  account  for 
caretakers  and  their  families.  Another  means  of  checking  the 
estimated  population  is  by  the  birth  rate,  if  this  remain  fairly 
constant  in  a  series  of  years;  and  this  computation  is  found 
generally  to  closely  approximate  to  the  truth,  when  applied  to 
large  populations.     Thereby  the  population  = 

registered  births  in  the  year  x  1,000 
average  birth  rate  for  previous  10  years' 

An  annual  birth  rate  or  death  rate  is  calculated  from  the 
number  of  births  and  deaths  respectively,  multiplied  by  1,000, 
and  then  divided  by  the  population.  The  births  or  deaths  are 
thus  expressed  as  so  many  to  every  thousand  persons  living. 

Birth  rates  and  death  rates  may  be  calculated  as  annual  rates 
to  1,000  persons  living  from  weekly,  monthly,  or  quarterly  returns. 
When  the  returns  are  for  a  less  period  than  a  year,  the  rate 
represents  the  number  of  births  or  deaths  that  would  take  place 
per  1,000  of  the  population  in  a  year,  if  the  proportion  of 
births  or  deaths  to  population  recorded  in  these  shorter  periods 
were  maintained  throughout  the  year.  Now,  the  correct  number 
of  days  in  a  natural  year  is  365-24226,  and  the  correct  number 
of  weeks  is  52-17747.  The  death  rate  may  therefore  be  accur- 
ately calculated  from  weekly,  monthly,  and  quarterly  returns 
as  follows  : 

A  weekly  death  rate  = 

number  of  deaths  recorded  in  week  x  52-17747  x  1,000^ 
the  population 
a  monthly  death  rate  = 

number  of  deaths  recorded  in  four  weeks  x  13  x  1,000  _ 
the  population 
a  quarterly  death  rate  should  deal  with  the  thirteen  weeks  which 
most  nearly  correspond  to  the  natural  quarter,  and  = 

number  of  deaths  recorded  in  quarter  x  4  x  1,000 
the  population 


STATISTICS  639 

A  better  method  of  stating  the  birth  rate  tlian  that  of  the 
ratio  of  births  per  annum  to  1,000  of  the  population  is  to  state 
the  proportion  of  births  per  1,000  women  of  conceptive  age,  i.e., 
15  to  45  years.  This  is  sometimes  called  the  "  corrected  " 
birth  rate.  If  this  method  is  adopted  it  is  desirable  to  carry 
the  analysis  further,  and  to  ascertain  also  the  proportion  of 
legitimate  births  per  1,000  married  women  aged  15-45,  and 
the  proportion  of  illegitimate  births  per  i.ooo  unmarried  and 
widowed  women  of  similar  age. 

England  and  Wales,   1900-2   (Average). 

Birth  rate  per  1,000  of  population    ....  28*0 

women  aged  15-45  .          .         .  114*8 

Legitimate  birth  rate  per  1,000  married  women        .  235-5 

Illegitimate     .,          ,,          ,,           unmarried     ,,           .  8-5 

In  large  towns  a  certain  number  of  deaths  occur  in  public 
institutions  (hospitals,  workhouses,  etc.),  which  have  to  be 
allotted  to  the  districts  in  which  the  deceased  persons  resided. 
In  London,  for  instance,  which  is  divided  into  a  number  of 
boroughs,  in  calculating  the  death  rate  of  any  borough,  the 
deaths  of  non-parishioners  which  occur  in  public  institutions 
in  the  borough  must  be  excluded;  whilst  deaths  of  parishioners 
occurring  in  the  pubHc  institutions  in  the  borough  and  outside 
it  must  be  included,  in  order  to  arrive  at  the  true  death  rate. 
In  London,  the  figures  required  for  this  purpose  are  now  supplied 
to  medical  officers  of  health  from  the  Registrar-General's  office. 
Formerly  it  was  the  custom  to  assign  to  each  sanitary  area,  out 
of  the  total  deaths  in  public  institutions  in  London,  a  number 
proportional  to  its  population. 

In  estimating  the  total  death  rate  of  a  combination  of  two  or 
more  districts,  which  exhibit  different  mortality  figures,  the 
method  of  taking  the  average  of  the  district  death  rates,  irre- 
spective of  population,  would  introduce  a  serious  error. 

Example. — If  A  has  a  population  of   10,000  and  a  death  rate  of  25 
per  1,000;  if  B  has  a  population  of  2,000  and  a  death  rate  of  10  per  1,000; 
and  if  C  has  a  population  of  7,000  and  a  death  rate  of  15  per  1,000,  the 
death  rate  of  the  combined  districts  with  a  population  of  19,000  is — 
/ 10,000  \      /  2,000         \      /  7,000  \ 

Vi97oc^^'v+ (19:000^  ^°)+ir^;^o^ '5  j= 

250-^20-1-105     375 

19  19        ^ ' 

If,  however,  the  average  of  25,  10,  and  15  had  been  taken,  viz.,  i6'6, 
an  error  of  3'i  per  1,000  would  have  been  committed. 


640  HYGIENE   AND    PUBLIC   HEALTH 

It  may  be  well  to  point  out  in  this  place — -especially  as  mis- 
understanding is  constantly  arising  on  the  subject — what  is  the 
true  significance  of  death  rates,  and  how  far  they  are  rehable 
as  tests  of  the  health  and  sanitary  surroundings  of  different 
communities. 

Death  rates  constructed  from  the  mortality  returns  of  short 
periods,  such  as  a  week  or  month,  are  not  reliable  as  tests  of 
health.  They  are  necessarily  subject  to  accidental  fluctuations, 
which  must  prevent  any  true  conclusions  being  drawn  from  them. 
So,  too,  with  the  death  rates  of  very  small  populations,  even 
when  they  exhibit  returns  covering  a  period  of  a  year.  The 
numbers  on  which  the  figures  are  founded  are  not  sufficiently 
large  to  exclude  those  accidental  fluctuations  from  varying  cir- 
cumstances which  must  be  got  rid  of  before  any  just  reasoning 
can  be  founded  on  death  rates.  It  is  different  with  the  death 
rates  from  yearly  returns  of  larger  populations.  Where  the  units 
on  which  the  figures  are  founded  are  sufficiently  large,  accidental 
fluctuations  are  submerged,  so  to  speak;  and  the  errors  traceable 
to  them  are  reduced  to  such  small  limits  that  trustworthy  con- 
clusions can  be  drawn. 

But,  in  comparing  death  rates  of  different  towns  or  districts 
with  each  other,  there  are  other  sources  of  error  which  must  be 
taken  into  account.  A  population  consists  of  a  number  of  people 
living  at  every  age,  from  the  time  of  birth  to  one  hundred  years 
or  more.  Now,  the  age  distribution  of  two  or  more  populations 
may  vary  widely,  the  proportions  of  children,  adults,  and  old 
people  to  the  total  population  being  often  very  different.  If  the 
death  rate  were  the  same  for  all  ages,  this  different  age  distribu- 
tion might  be  neglected.  But  such  is  not  the  case;  children 
under  five  and  old  people  over  fifty-five  years  of  age  die  at  a 
greater  rate;  while  those  from  the  age  of  five  up  to  fifty-five  die 
at  a  less  rate  than  that  represented  by  the  general  rate.  There 
is  another  disturbing  factor,  and  that  is  the  proportionate 
number  of  males  to  females  in  any  population.  Females  at  all 
ages  have  lower  death  rates  than  males,  except  in  the  age  period 
five  to  fifteen,  when  the  female  rate  is  slightly  higher.  The 
causes  of  the  higher  male  mortality  are  chiefly  to  be  found  in 
their  more  exacting  and  dangerous  occupations  and  their  greater 
indulgence  in  alcohol.  The  census  of  1901  showed  that  there 
were  106-9  females  to  every  100  males  in  the  population  of 
England  and  Wales. 


STATISTICS  641 

The  following  table  exhibits  the  death  rates  at  different  age 
periods  (calculated  upon  the  numbers  living  at  each  age  period) 
amongst  males  and  females  in  England  and  Wales. 

England  and  Wales  during  the  Year  1910. 


I 

Males. 

Females. 

All  ages 

14-4 

12-7 

Under  5  years 

37-5 

30-9 

S-io 

2.9 

2-9 

lo-is 

1-8 

1-9 

15-20 

2-6 

2-4 

20-25 

3-5 

2-9 

25-35 

4-8 

4-2 

35-45 

8-5 

7-1 

45-55 

iS-S 

I2'I 

55-65 

31-5 

23-5 

65-75 

69-7 

56-4 

75-85 

132-0 

119-4 

85  and  upwards  . 

293.6         j 

280-5 

(From  the  Annual  Reports  of  the  Registrar-General.) 

From  these  figures  it  will  be  seen  that  it  would  not  be  right 
to  compare  the  general  death  rates  of  two  towns,  one  of  which, 
let  us  suppose,  had  a  larger  proportion  of  females  and  of  young 
adults,  and  a  smaller  proportion  of  males  and  old  people,  than 
the  other.  Corrections  must  therefore  be  made  for  differences 
in  the  age  and  sex  distribution.  It  is  for  this  reason  that  the 
uncorrected  death  rates  of  rural  districts  overstate,  whilst  the 
death  rates  of  large  cities  understate,  the  real  mortality. 

Besides  normal  increase  of  population  by  excess  of  births  over 
deaths,  the  immigration  into  large  towns,  which  always  greatly 
exceeds  the  emigration  from  them,  tends  to  bring  large  numbers 
of  young  adults  into  the  population,  and  so  influences  the  age 
distribution. 

The  following  table  gives  the  age  distribution  of  1,000  persons 
in  England  and  Wales  (mean  of  censuses  of  1891  and  1901)  : 


All 
Ages. 

1,000 

Under 

5 

5-10 

10-15 

15-20 

20-25 

25-35 

.S5-45 

45-55 

55-65 

65-75 

75  and 
upwards 

13 

119 

112 

107 

lOI 

93 

156 

119 

88 

58 

34 

The  Registrar-General  has  adopted  the  following  method  for 

making  the  necessary  corrections  for  age  and  sex  distribution  in 
any  population  (Annual  Summary,  1883)  : 

41 


642  HYGIENE   AND   PUBLIC   HEALTH 

The  standard  death  rate  of  the  population  is  first  obtained. 
This  is  a  death  rate  calculated  on  the  hypothesis  that  the  mor- 
tality of  the  population  at  each  age  period  and  for  each  sex  corre- 
sponds to  that  obtaninig  in  England  and  Wales  as  a  whole.  The 
facts  as  to  the  age  and  sex  distribution  of  the  population  of  any 
area  are  ascertained  from  the  last  census  returns,  and  thus  the 
population  can  be  split  up  into  the  numbers  living  of  both  sexes 
at  the  different  age  periods.  Then,  for  the  purpose  of  calculating 
the  standard  death  rate  of  the  district,  it  is  assumed  that  those 
living  in  each  of  the  groups  will  die  at  the  same  rate  as  those 
dying  in  the  similar  age  periods  in  England  and  Wales  generally; 
and  thus  a  hypothetical  number  of  deaths  is  arrived  at,  on  the 
basis  of  applying  the  death  rates  of  England  and  Wales  at  different 
age  periods  to  those  living  at  such  periods  in  the  particular 
population  under  consideration.  The  total  deaths  thus  cal- 
culated X  1,000,  and  divided  by  the  population  under  considera- 
tion, will  furnish  the  standard  death  rate.  Now,  it  is  obvious 
that  if  any  town  has  the  same  relative  proportions  of  males  and 
females  in  the  different  age  periods  as  England  and  Wales,  then, 
if  the  mortality  rates  of  England  and  Wales  for  each  of  these 
age  periods  and  for  both  sexes  are  applied  to  these  proportions, 
the  standard  death  rate  of  that  town  will  be  the  same  as  the 
death  rate  of  England  and  Wales.  Any  difference,  therefore, 
can  only  be  due  to  the  fact  that  the  town  population  has  a 
different  age  and  sex  distribution. 

The  death  rate  of  England  and  Wales  is  therefore  divided  by 
the  calculated  standard  death  rate;  and  thus  a  factor  is  ob- 
tained which,  when  multiplied  into  the  recorded  death  rate, 
serves  to  make  allowance  for  differences  of  age  and  sex  distribu- 
tion, and  to  furnish  a  corrected  death  rate — comparable  with 
that  of  England  and  Wales  and  of  other  towns  corrected  on 
the  same  basis.  As  an  example  of  the  method  of  arriving  at  a 
corrected  death  rate,  the  table  on  p  643  may  be  given  (News- 
holme's  Vital  Statistics). 

The    standard    death    rate    for    Huddersfield   is    (see  Table) 

—^ '- .^16-47    per    1,000.      The    annual    death    rate    of 

95,420 

England    and   Wales   in    1881-90    was    19-15.     The    factor    for 

correction  for  Huddersfield  is,  therefore, 

'    ^==1-1627 
10-47 


STATISTICS 


643 


The  age  and  sex  distribution  (;f  Huddersfield  is  thus  seen  to  be 
more  favourable  to  a  low  death  rate  than  that  for  the  country 
as  a  whole;  and  when  the  recorded  death  rate  is  multiplied  by  the 
factor  and  brought  into  comparison  with  the  death  rate  of  England 
and  Wales,  it  is  thereby  increased.  As  a  general  rule,  in  rural  dis- 
tricts the  age  and  sex  distribution  of  the  population  is  less  favour- 
able to  a  low  death  rate  than  that  in  urban  districts  (Newsholme). 


Ages. 

Mean  Annual  Death 

Rate  of  Kngland  and 

Wales,  1881-90,  per 

1,000  living  at  each 

Group  of  Ages. 

Population  of 

Huddersfield 

in  1891. 

Calculated 

Number  of 

Deaths  in 

Huddersfield. 

1 
Males.     Females. 
280         249 

25  27 
15            16 
21              25 

26  30 
58             65 

69         66 
76         70 
83         86 
79         96 
41         69 

773       799 

1.572 

Under 

5- 
10- 

15- 
20- 

25- 
35- 
45- 
55- 
65- 
75  anc 

5 
upw 

ards 

Males.          Females. 

61-59         51-95 
5-35           5-27 
2-96           3-1 1 

4-33           4-42 

5-73            5-54 

7-78           7-41 

12-41          10-61 

19-36         15-09 

34-69         28-45 

70-39         60-36 

162-62        147-98 

Males.            Females. 
4,551            4,785 
4,691             5,081 

5,113            5,165 
4,905            5,549 
4,541             5,461 
7,466            8,834 
5,576            6,265 
3,944            4,649 
2,393            3.017 
1,128            1.590 
250                466 

Totals    . 

44.558         50,862 

95.420 

The  factor  for  correction  exceeds  unity  in  twenty-six  out 
of  the  twenty-eight  large  towns  of  the  Registrar-General,  thus 
showing  that  their  death  rates  without  correction  are  under- 
stated; and  the  factor  is  less  than  unity  in  the  remaining  two 
towns,  in  these  two  cases  the  uncorrected  death  rates  being 
overstated  compared  with  the  country  generally. 

The  comparative  mortality  figure  is  a  useful  means  of  expressing 
a  comparison  of  the  mortalities  of  different  districts.  For  any 
year  it  is  ^j^^  corrected  death  rate  x  1,000 

death  rate  of  England  and  Wales 

Taking  Huddersfield,  again,  as  an  example:  the  death  rate  of 
England  and  Wales  for  1897  was  17-43,  and  that  for  Huddersfield 
was  19-07;  the  comparative  mortality  figure  of  that  town  for  1897 
was,  therefore: 


19-07  X  1,000  _ 
17-43 


094. 


64^  HYGIENE  AND  PUBLIC  HEALTH 

This  implies  (hat,  after  making  allowance  for  age  and  sex 
distribution  of  the  population,  the  number  of  living  persons 
that  in  England  and  Wales  in  1897  furnished  1,000  deaths  in 
Huddersfield  actually  furnished  1,094. 

The  number  of  males  and  females  living,  and  the  mean  death 
rates  for  1881-90  at  the  twelve  age  periods,  among  a  million 
persons  in  England  and  Wales,  has  been  termed  the  "  Standard 
Million."  ^  This  is  also  of  great  utility  as  a  uniform  standard  of 
comparison  of  the  mortality  of  different  districts  with  one  another 
and  with  the  whole  country. 

Having  ascertained  the  death  rate  for  the  age  and  sex  groups 
in  the  population  of  a  given  district,  the  number  of  deaths 
which  would  have  occurred  in  each  of  the  similar  age  and  sex 
groups  of  "  the  standard  million,"  if  subject  to  the  same  mortality, 
is  calculated.  From  the  sum  of  these  deaths  a  death  rate  is 
calculated  for  the  district,  and  this  is  termed  the  "  corrected  " 
death  rate,  for  it  is  the  death  rate  which  would  have  prevailed 
had  the  age  and  sex  distribution  of  the  population  of  the  district 
been  the  same  as  that  of  England  and  Wales  as  a  whole. 

In  many  parts  of  large  towns  the  density  of  population  is 
very  great — 200  persons  to  an  acre  or  more — and  the  death  rate 
correspondingly  high.  The  high  death  rates  which  go  with 
dense  population  are  not  simply  the  result  of  aggregation. 
Aggregation  means,  no  doubt,  generally  polluted  air  and  possibly 
polluted  water  and  soil,  and  the  easy  spread  of  infectious  disease. 
But,  as  Dr.  Ogle  has  pointed  out,  the  more  crowded  a  community, 
the  greater  the  amount  of  abject  want,  filth,  crime,  drunkenness, 
and  other  excesses,  the  more  keen  is  the  competition,  and  the 
more  feverish  and  exhausting  the  conditions  of  life.  It  is,  too, 
in  these  crowded  communities  that  the  most  dangerous  and  un- 
healthy industries  are  carried  on.  These  indirect  consequences 
of  aggregation  influence  the  mortality  greatly  more  than  the 
direct. 

The  death  rate  from  a  disease  affecting  only  a  particular  class 
should  be  expressed  as  the  number  of  these  deaths  to  every  1,000 
of  those  who  are  liable  to  contract  the  disease.  The  death  rate 
from  puerperal  fever,  for  instance,  should  be  taken  as 

the  deaths  from  puerperal  fever  x  1,000 
the  number  of  registered  births 

^    Ftive  Supplement  to  the  55th  Annual  lieport  of  the  Registrar-General. 


STATISTICS  645 

since  it  is  only  those  females  who  have  recently  been  delivered 
of  a  child  who  are  liable  to  die  from  this  complaint. 

The  general  death  rate  fluctuates  considerably  throughout 
the  year.  In  large  communities  it  is  generally  high  through 
January,  February,  and  March,  and  falls  considerably  through 
April,  May,  and  June.  It  often  rises  again  through  July  and 
August,  to  fall  in  September  and  October,  and  it  again  rises 
in  November  and  December. 

Mild  winters  and  cool  summers  favour  a  low  death  rate,  from 
the  lessened  mortality  from  respiratory  diseases  and  intestinal 
diseases,  respectively. 

In  determining  the  cause  of  death  or  the  origin  of  an  outbreak 
of  disease,  much  more  than  the  mere  concurrence  of  two  pheno- 
mena is  required  to  prove  their  relation  as  cause  and  effect. 
The  inductive  methods  of  agreement,  of  difference,  and  of  con- 
comitant variations  must  be  worked  through,  and  the  possibility 
of  a  plurality  of  causes  should  never  be  lost  sight  of. 

The  number  of  deaths  at  a  special  age  period  must  not  be  stated 
as  a  proportion  of  the  total  population,  for  a  fallacy  is  involved 
in  attempting  to  establish  a  relationship  between  two  factors, 
both  of  which  are  variable.  The  number  of  deaths  at  a  certain 
age  period  must  be  expressed  as  a  proportion  of  the  number 
living  at  the  age  in  question,  this  number— as  we  have  seen — 
varying  considerably  in  different  communities.  The  special 
disease,  also,  may  be  one  affecting  chiefly  a  certain  age  period 
and  sex,  and  a  like  error  will  be  involved  if  the  rate  is  not 
expressed  as  per  1,000  of  the  population  living  at  the  same 
ages  and  of  the  same  sex  as  those  attacked. 

Thus,  more  than  90  per  cent,  of  the  deaths  from  scarlet  fever 
occur  among  children  under  ten  years  of  age.  Now,  children 
under  ten  amount  to  25  per  cent,  of  the  population  of  Berlin, 
but  only  to  12-4  per  cent,  of  that  of  Paris.  An  equal  death  rate 
from  scarlet  fever  in  the  two  cities  would,  therefore,  imply  a 
mortality  twice  as  great  in  Paris  as  in  Berlin. 

The  annual  birth  rate  in  England  and  Wales  is  now  about  25-1 
per  1,000  (1910) .  The  birth  rate  has  steadily  declined  since  the  year 
1876,  when  it  was  36-3  per  1,000,  and  the  highest  recorded  rate  of 
any  year  since  civil  registration  began  (1839).  The  now  prevaihng 
rate  is  lower  than  that  of  any  year  in  the  same  period  (1839- 1908). 

In  1910,  15-0  persons  were  married  per  1,000  of  the  population 
in   England   and  Wales.     The   marriage  rate  fell  continuously 


646 


HYGIENE  AND  PUBLIC  HEALTH 


from  the  year  1873  (17-6  persons  married  per  1,000)  to  the  year 
1886  (14-2  per  1,000),  but  has  since  sHghtly  risen  again. 

The  lowest  annual  death  rate  in  England  and  Wales  ever 
recorded  since  civil  registration  began  was  in  the  year  1910,  the 
rate  being  13-5  per  1,000.  A  high  mortality  prevailed  in  the 
four  years  1890,  1891,  1892,  and  1893,  the  average  death  rate 
being  19-5  per  1,000,  which  is  attributable  to  the  prevalence  of 
influenza  in  those  years  and  to  a  great  fatality  from  lung  diseases, 
the  sequelae  of  influenza. 

The  mean  annual  death  rate  of  the  ten  years  1861-70  was 
22-5  per  1,000;  of  the  ten  years  1871-80,  21-4  per  1,000;  of 
the  ten  years  1881-90,  19-1  per  1,000,  and  of  the  ten  years 
1891-1900,  i8-2  per  1,000.  The  mean  rate  for  the  ten  years 
1901-1910  was  only  15-4.  Although  to  a  great  extent  this 
lowered  death  rate  must  be  credited  to  the  operation  of  the 
Public  Health  Acts,  and  the  more  stringent  application  of  these 
Acts  and  of  local  by-laws,  still,  it  must  not  be  forgotten  that  the 
lowered  birth  rate  would  conduce  to  a  lowering  of  the  death  rate 
for  some  few  years  at  least,  as  the  proportion  of  children  under 
five  years  of  age,  whose  death  rate  is  high,  would  be  diminished, 
and  the  ratio  of  older  children  and  adults  to  the  entire  population 
would  be  increased.  If  the  birth  rate  continues  to  fall,  as  it 
has  done  in  the  last  twenty  years,  we  may  expect  the  death  rate 
eventually  to  rise  again,  owing  to  the  increase  in  the  mean  age 
of  the  population,  and  a  consequently  increased  ratio  of  old 
people  (over  fifty-five  years)  to  the  total  population. 

It  is  a  remarkable  fact  that  the  death  rate  in  town  or  urban 
districts  has  declined  to  a  greater  extent  than  that  in  rural 
districts,  as  the  following  table  (from  the  53rd  Annual  Report 
of  the  Registrar-General)  shows : 


Years. 

Death  Rate  per  i,ooo  Persons  living. 

England  and 

Town 

Country 

Wales. 

Districts. 

Districts. 

1851-60 

22*2 

24-7 

19-9 

1861-70 

22'5 

24-8 

19-7 

1871-80 

21-4 

23-1 

19-0 

1881-90 

I9-I 

20-3 

17-3 

I  891-1900 

l8-2 

20-3! 

14-9- 

I905-I909 

.  1         IS-I 

16-61 

12-62 

^  Urban  Counties. 

2  Rural    Counties     (Sujiplcmcnt    to    65tli    Ann. 
Corrected  for  age  and  sex  distribution. 


Rej^t.    of    Reg. -Gen.). 


STATISTICS  647 

This  means  that  sanitary  measures  carried  out  in  towns,  where 
they  were  most  needed,  have  done  more  to  prolong  human  life 
than  in  the  country,  and  that  sanitary  improvements  have  been 
undertaken  with  greater  vigour  and  thoroughness  in  urban 
districts. 

It  is  very  necessary,  in  comparing  the  death  rates  in  towns 
and  country  districts  respectively,  to  correct  for  the  very  different 
age  and  sex  distributions  in  the  country  and  in  towns,  which  are 
due  to  the  immigration  of  those  in  the  middle  age  periods  from 
the  country  districts  into  the  towns  with  the  object  of  finding 
employment  there  at  better  wages. 

The  leading  causes  which  serve  to  raise  the  death  rates  of  towns 
above  those  in  country  districts  are  as  follows : — Overcrowding, 
which  directly  causes  disease  and  promotes  the  spread  of  com- 
municable illness,  especially  summer  diarrhoea,  measles,  and 
phthisis;  the  higher  birth  rates,  attended  with  a  higher  rate 
of  infantile  mortality,  and  a  higher  zymotic  death  rate;  the 
less  healthy  occupations;  the  greater  amount  of  profligacy  and 
intemperance;  the  larger  number  of  accidents;  the  existence 
of  many  public  and  private  institutions  for  the  reception  of  the 
sick,  which  attract  people  from  the  neighbouring  rural  districts, 
and  the  fact  that  some  of  the  deaths  occurring  in  these  institu- 
tions may  not  be  allotted  to  the  districts  from  which  the  sufferers 
came. 

We  are  now  in  a  position  to  understand  the  influence  of  birth 
rate  upon  death  rate.  In  large  towns  high  death  rates  go  with 
high  birth  rates  ;  but,  as  pointed  out  by  the  late  Dr.  Farr,  high 
death  rates  are  not  the  result  of  high  birth  rates;  they  are  more 
generally  caused  by  density  of  population  (overcrowding  on 
space  and  in  houses)  and  by  bad  sanitary  conditions.  High  birth 
rates  should  cause  a  lowered  death  rate;  for  if  year  by  year 
the  births  exceed  the  deaths  amongst  a  population,  not  only  are 
additional  children  under  five  years  of  age,  whose  mortality  is 
high,  added  to  the  population,  but  a  still  larger  increase  of  those 
between  ten  and  forty,  whose  mortality  is  low,  takes  place  and 
counterbalances  the  other;  whilst  the  proportion  of  old  people 
over  fifty-five  years  of  age  to  the  total  population  is  diminished. 
A  high  birth  rate,  therefore,  continuing  over  a  period  of  years,  is 
favourable  to  a  low  death  rate,  and  a  low  birth  rate  to  a  high 
death  rate.  If  we  find — as  is  actually  the  case — that  a  rural 
district  with  a  low  birth  rate  has  also  a  low  death  rate,  whilst 


648 


HYGIENE    AND    PUBLIC    HEALTH 


an  urban  district  with  a  high  birth  rate  has  a  high  death  rate, 
we  must  conclude  that  the  sanitary  surroundings,  the  occupa- 
tions, or  the  social  conditions,  of  the  rural  districts  are  more 
favourable  to  life  than  those  of  the  urban.  These  are  the 
main  causes  of  the  varying  health  conditions  of  populations, 
of  which  death  rates,  with  certain  limitations,  afford  trust- 
worthy evidence. 

The  higher  birth  rate  in  large  urban  districts  is  due  to  the 
following  causes: — The  greater  proportion  of  women  at  child- 
bearing  ages,  the  higher  marriage  rate,  the  earlier  marriages, 
and  the  greater  infantile  mortahty.  The  state  of  national  pros- 
perity to  a  large  extent  determines  the  birth  and  marriage 
rates. 

The  marriage  rate  is  usually  expressed  as 

number  of  marriages  x  1,000 
population 

but  it  should  more  properly  be  expressed  as  the  number  of  persons 
married  annually  per  1,000  marriageable  persons  —  i.e.,  those 
over  fifteen  years  who  are  unmarried. 

The  marriage  rate  is  highest  in  large  towns  to  which  man}^ 
young  adults  emigrate  from  country  districts,  and  where  more 
constant  labour  at  a  higher  rate  of  remuneration  than  in  the 
country  can  be  secured.  The  average  annual  fecundity  of 
married  women  of  reproductive  ages  is  about  260  live  births  to 
1,000  women. 

Mean  Annual  Birth  Rates  per  1,000  in  England  and  Wales.  1 


Calculated  on 

Total  Populatioi 

at  all  Ages. 

Calculated  on 
Female  Popula- 
tion, aged  15-45- 

Legitimate 
Birth  Rate  cal- 
culated on 
Married  Female 
Population, 
aged  15-45. 

Illegitimate 
Birth^Rate  cal- 
culated on 
LTnniarried  and 
Widowed  Female 
Population, 
aged  15-45. 

1 870-2    . 
1880-2   . 
1890-2    . 
1900-2    . 
1908 

35-3 
34-0 

30-7 
28-6 
26-5 

153-7 
147-7 
129-7 

114-8 
io6-i 

292-5 
286-0 
263-3 

235-5 
217-6 

I7-0 

I4-I 
IO-5 

8-5 
8-0 

Approximately  70  per  cent,  of  the  decrease  in  the  birth  rate 
during  the  past  35  years  (based  on  the  proportion  of  births  to 

'  Sixty-seventh  Annual  Report  of  the  Registrar-GeneraL 


STATISTICS 


649 


the  female  population  aged  15-45)  results  from  decreased  fertility 
of  married  women,  some  part  of  this  decrease  being  attributable 
to  changes  in  their  age  constitution;  about  10  per  cent,  may  be 
ascribed  to  the  decrease  of  illegitimacy,  while  the  remaining  20 
per  cent,  is  due  to  the  decrease  in  the  proportion  of  married 
women  of  conceptive  ages  in  the  female  population. 

The  tendency  in  modern  times  to  postpone  marriage  to  a  later 
age  than  formerly  is  shown  by  the  fact  that  in  1871  15-2  per  cent, 
of  the  married  women  aged  15-45  were  comprised  in  the  group 
15-25  years  of  age,  whereas  in  1901  only  12-4  per  cent,  of  the 
married  women  were  in  this  group.  The  later  age  of  marriage  for 
women  curtails  the  period  within  which  children  can  be  born. 

Mean  Annual  Birth  Rates  per  1,000  in  Urban  and  Rural  Areas. 


Ukdan. 

Rural. 

Calculated  on 

Total  Population 

at  all  Ages. 

Calculated  on 
Female  Popula- 
tion, aged  15-45. 

Calculated  on 

Total  Population 

at  all  Ages. 

Calculated  on 
Female  Popula- 
tion, aged  15-45. 

158-9 

153-5 
135-6 

I20'7 

1870-2    . 
1880-2   . 
1 890-2    . 
1900-2    . 

36-7 

35-7 
32-0 
29-8 

143*1 
140-6 
124-6 
III-4 

31*6 
30-3 
27-8 
26-0 

The  lowering  of  the  birth  rate  is  seen  from  this  table  to  be  as 
much  a  feature  of  rural  as  of  urban  communities. 

The  best  statistical  evidence  of  the  health  of  a  community 
is,  of  course,  furnished  by  the  corrected  death  rate,  although  a 
sick  rate  ("  morbidity  rate  ")  would  furnish  still  better  evidence. 
The  registration  of  sickness,  however,  would  be  open  to  many 
fallacies  and  abuses.  The  scant  returns  which  are  available  in 
this  country  (i.e.,  from  sick  clubs,  friendly  societies,  industrial 
organizations,  hospitals,  army,  navy,  police,  etc.)  are  only 
concerned  with  disabling  sickness,  among  what  are  often  selected 
lives,  and  are  of  little  value  for  the  purpose  under  consideration. 
On  an  average,  there  are  two  years  of  sickness  suffered  to  each 
death  registered. 

The  death  rates  from  the  principal  zymotic  diseases,  from 
tuberculosis,  phthisis,  and  acute  diseases  of  the  lungs,  afford 
most  valuable  evidence  of  sanitary  condition.  The  zymotic 
death  rate  is  the  number  of  deaths  from  the  seven  principal 
zymotic  diseases  multiplied  by  1,000  and  divided  by  the  popu- 


650 


HYGIENE    AND    PUBLIC    HEALTH 


lation.  The  seven  principal  zymotic  diseases  of  the  Registrar- 
General  are  small-pox,  measles,  scarlet  fever,  diphtheria, 
whooping-cough,  "  fever  "  (i.e.,  typhus,  enteric  fever,  and  simple 
continued  fever),  and  diarrhoea.  The  zymotic  death  rate  for 
England  and  Wales  in  1910  was  1-02.  Of  these,  enteric  fever 
mortality  is  the  best  test  of  sanitary  condition,  caused  as  it  is  by 
specific  faecal  contamination  of  soil  and  water;  whilst  diarrhoea, 
with  its  special  incidence  on  young  children,  is  notably  associated 
with  insanitary  surroundings.  The  other  zymotic  diseases, 
although  probably  favoured  in  their  onset  and  fatahty  by  un- 
hygienic conditions,  also  indicate,  when  the  mortality  from  them 
is  high,  a  failure  on  the  part  of  the  sanitary  authority  to  control 
their  spread  by  disinfection  and  isolation.  Tuberculosis,  phthisis, 
and  acute  diseases  of  the  lungs,  are  most  prevalent  and  most  fatal 
among  communities  where  overcrowding  in  dwellings  or  work- 
shops is  allowed  to  exist,  or  where  sites  are  damp  and  the  subsoil 
saturated  with  water.  They  may  thus  be  taken  as  evidence  of 
a  certain  class  of  insanitary  conditions,  usually  associated  with 
poor  town  populations.  The  rate  of  infantile  mortahty,  though 
influenced  solely  by  conditions  affecting  those  under  one  year  of 
age,  also  ranks  high  as  evidence  of  the  health  of  a  community. 


Annual  Death  Rate  per  1,000  in  187 1-8 

1901-1910. 


1881-90,    189I-I9OO,    AND 


England  and  Wales  (Persons). 

1871-80. 

1881-90. 

1891-1900. 

1901-1910. 

All  causes             .... 

21-27 

19-08 

18-21 

15-37 

Small-pox 

0-23 

0-04S 

0-013 

0-013 

Measles 

0.38 

0-44 

0-414 

0-309 

Scarlet  fever 

0*72 

0-33 

0-158 

0-106 

Diphtheria 

0-12 

o-i6 

0-263 

0-179 

Whooping  cough 

0-5I 

0-4S 

0.378 

0-277 

Tyj^hus 

0'06 

0-015 

0-003 

0-00 1 

Enteric  fever 

0-32 

0-20 

0-174 

0-091 

Simple  continued  fever 

O'lO 

0-025 

0-006 

0-002 

Diarrhoea  and  dysentery 

0.93 

0-67 

0-734 

0-57I 

Zymotic  diseases 

3-47 

2-36 

2-143 

1-017 

Phthisis 

2'12 

1-72 

1-392 

1-162 

Other  tubercular  diseases 

^'•7S 

0-70 

0-622 

0-493 

Cancer 

()"46 

0-58 

0-7SS 

0-903 

The  mean  age  at  death  of  a  population  is  obtained  by  adding 
together  the  ages  at  which  people  die,  and  dividing  the  number 


STATISTICS  651 

of  years  lived  by  the  number  of  deaths.  It  is  merely  an  expres- 
sion of  the  average  age  at  death  of  a  population  and  gives  no  evi- 
dence of  the  health  or  sanitary  condition  of  the  community. 
When  a  population  is  rapidly  increasing  by  excess  of  births 
over  deaths,  the  mean  age  at  death  is  low,  because  the  population 
is  largely  composed  of  young  persons.  When  a  population  is 
nearly  stationary,  the  proportion  of  old  people  to  the  total  popu- 
lation is  large,  and  the  mean  age  at  death  is  high.  The  mean 
age  at  death,  therefore,  gives  information  as  to  the  ages  of  the 
dying  and,  per  contra,  of  the  living  in  different  communities,  but 
nothing  more. 

A  life  table  represents  a  generation  of  individuals  passing 
through  life  to  extinction.  The  calculations  of  a  life  table  relate 
to  an  arbitrary  number  of  individuals  supposed  to  be  born 
simultaneously,  and  to  exist  under  the  same  conditions  as  those 
which  apply  to  a  given  community.  Usually  the  population  is 
assumed  to  start  with  a  million  births,  and  these  are  divided  into 
males  and  females  in  proportion  to  the  actual  number  of  births 
of  either  sex  that  have  occurred  in  the  given  community  during 
an  intercensal  period  of  ten  years.  The  mathematical  probability 
of  survival  of  every  individual  for  each  year  of  life  is  then  cal- 
culated from  data  obtained  from  the  actual  community,  and  thus 
the  hypothetical  life  table  population  becomes  the  medium  for 
the  record  of  facts  concerning  the  vitality  of  a  given  popu- 
lation. 

The  probability  of  survival  from  the  beginning  to  the  end  of 
each  age-period  = 

The  number  of  survivals  at  the  end  of  the  period 
The  number  living  at  the  beginning  of  period 

and  for  the  purposes  of  a  life  table  the  numbers  of  either  sex  living 
at  the  end  of  each  age-period  may  be  obtained  by  multiplying 
the  number  commencing  the  period  by  the  above  fraction.  By 
this  means  the  numbers  in  each  successive  age-period  are  gradu- 
ally diminished  to  extinction,  since  the  factor  is  always  less  than 
unity.  The  column  of  the  Hfe  table  showing  the  number  of 
survivors  at  each  age-period  for  both  sexes  is  thus  obtained.  It 
need  hardly  be  said  that  the  larger  the  number  of  the  population 
involved,  and  the  longer  the  period  of  time  from  which  the  data  of 
the  population  are  obtained,  the  more  reliable  will  be  the  various 
estimations  of  the  Hfe  table.     Hence  it  is  a  common  practice 


652  HYGIENE    AND    PUBLIC    HEALTH 

to  take  the  mean  figures,  both  as  to  population  and  deaths  at 
different  ages,  from  the  accumulated  data  of  two  censuses  and  the 
intervening  years.  But  the  above  facts  are  first  obtained  in  five 
and  ten  yearly  age-and-sex  groups  of  the  population,  so  that 
the  lives  and  deaths  of  each  age-group  have  to  be  distributed 
artificially  to  each  year  of  age  included  in  the  groups.  The  fact 
that  several  methods  may  be  adopted  for  this  distribution  accounts 
for  the  main  differences  in  construction  of  various  life  tables.  In 
many  tables  the  "  graphic  "  method  has  been  adopted.  The 
method  is  briefly  as  follows : — -On  paper  ruled  into  equal  squares 
is  laid  down  a  base  line  or  Abscissa,  and  along  this  are  marked 
off  the  proper  number  of  squares  representing  the  different  age- 
periods.  On  the  base  line  is  constructed  a  series  of  parallelograms 
of  such  a  height  that,  in  accordance  with  a  scale  of  population 
given  at  the  left-hand  margin,  the  area  of  the  parallelograms 
shall  represent  the  total  number  of  lives  at  risk  for  each  age-period. 
Thus,  if  for  males  the  total  number  of  lives  at  risk  for  ages 
0-5   has  been  found  to  be  20,000,   the  parallelogram  for  this 

age-period  should  read  to  the  height  of  ! =  4,000,  against 

5 
the  scale  of  population.  A  curved  line  is  now  drawn  through 
the  upper  borders  of  these  parallelograms,  as  free  from  bends 
and  irregularities  as  possible,  and  in  such  a  fashion  that  the 
area  cut  off  from  each  parallelogram  shall  be  equal  to  the  area 
added  to  the  same.  The  base  line  is  already  divided  into 
equal  spaces  representing  single  years  of  life,  and  vertical  lines 
are  drawn  through  the  centre  of  each  of  these  spaces  upwards 
to  join  the  curved  line.  The  height  to  the  point  of  jmiction  of 
each  of  these  vertical  lines  with  the  curved  line  above  referred  to 
is  read  off  against  the  scale  of  population,  and  will  give  the  fives 
or  deaths  for  the  middle  of  each  year  of  age  (see  fig.  91). 

The  mean  population  (or  the  number  of  lives  at  risk)  for  each 
year  of  age  during  the  ten  years  under  consideration  may  be 
calculated  as  follows:  The  population  at  the  census  1901,  and 
again  at  the  census  of  1911,  is  first  split  up  into  its  age  and  sex 
distribution  in  thirteen  age  periods;  the  "  central  "  population  in 
the  middle  of  1901  and  1911  for  each  such  group  is  then  calculated 
logarithmetrically.  The  annual  increase  per  unit  for  each  age 
and  sex  group  is  next  calculated  (one-tenth  of  the  log.  of  central 
population  in  1911  — one-tenth  of  the  log.  of  central  population 
in  1901=  log.   of  annual   increase   per  unit).      The  total  mean 


STATISTICS  653 

population  (or  lives  "  at  risk  ")  for  each  age-group  and  sex  for 
the  ten   years  is   then — 

Central  population  1911 — central  population  1901 
R-i 

when  R=  annual  increase  per  unit.  Now  we  have  the  mean 
total  hves  at  risk  in  each  age  and  sex  group,  and  by  means 
of  the  graphic  method  we  may  find  the  lives  at  risk  for  each  year 
of  life ;  and  by  similar  methods  we  may  deduce  the  mean  number 
of  deaths  for  each  year. 

If  the  lives  at  risk  in  any  year  constitute  a  "  central  "  popula- 
tion for  that  year — and  it  is  assumed  that  the  deaths  are 
uniformly  distributed  throughout  that  year — then  the  proba- 
bility of  surviving  any  one  year= 

lives  at  risk  — I  the  deaths  in  the  year_ 
lives  at  risk  +  ^  the  deaths  in  the  year 

and  as  the  mortality  rate  for  the  year  in  question  is,  of  course, 
a  rate  per  1,000,  it  follows  that  the  number  of  persons  living 
in  any  year  multiplied  by  : 

1,000—^  the  mortality  rate  for  that  year 
1,000  + 1  the  mortality  rate  for  that  year 

furnishes  the  number  completing  that  year.  Thus,  if  the 
mortality  rate  for  the  second  year  of  life  be  taken  as  24  per  1,000, 
and  the  survivors  at  the  end  of  the  first  year  of  life  be  taken 
as  90,000,  the  probability  of  anyone  surviving  the  second  year 
of  life  = 

1,000  —  ^  24      988 

1,000  +  ^  24     1,012 
and  the  survivors  at  the  end  of  the  second  year  of  life  would 

number     "      x  90,000=  87,865. 
1,012 

The  most  important  columns  of  a  life  table  for  any  popu- 
lation show  the  numbers  surviving  at  each  year  of  age,  the 
years  of  life  lived  subsequent  to  each  year  of  age,  the  sum  of  the 
years  lived  in  and  after  each  year  of  age,  and  "  the  mean  after 
lifetime  "  or  "  expectation  of  life  at  any  age." 

The  life  table  is  very  valuable  for  comparing  the  vitality  of 
a  community  at  one  period  with  that  of  another  period,  or  with 
that   of   another   community.     By   furnishing,    by   the   law   of 


654 


HYGIENE    AND    PUBLIC   HEALTH 


probability,  the  expectation  of  life  of  the  different  members 
of  the  community,  it  supphes  a  valuable  comparative  figure 
for  vital  statistical  purposes,  and  one  which,  by  enabling  us  to 
measure  the  probability  of  life  and  death,  affords  a  scientific 
basis  on  which  the  calculations  for  Hfe  assurance  are  made. 

A  life  table  constructed  by  the  late  Dr.  T.  E.  Hayward 
is  made  to  show  what  the  effect  on  the  longevity  of  the  present 
population  of  this  country  would  be  (i)  if  phthisis  could  be 
eliminated  as  a  cause  of  death,  and  (2)  if  the  high  phthisis  mor- 
tality formerly  prevaihng  was  now  being  maintained. 


5-10  )0I6    I5?0  ?02S      26  36        35  45 


8S  95        86105 


Fig.   91.- 


-Graphic  Method.     Male  Population — Numbers  Living  or 
Lives  at  Risk. 


The  mean  duration  of  life  or  expectation  of  life  at  birth  differs 
widely  from  the  mean  age  at  death,  when  the  population  is  con- 
tinuously disturbed  by  a  fluctuating  birth  rate,  immigration, 
and  emigration,  although  when  the  population  is  stationary  they 
coincide.  Thus,  the  mean  duration  of  life  in  England  (1881-90) 
for  males,  as  calculated  from  a  life  table,  was  43-66  years; 
whereas  the  mean  age  at  death  was  only  twenty-nine  years.  It 
must  be  borne  in  mind  that  this  difference  is  due  to  the  fact  that 
\he  mean  duration  of  life  is  calculated  from  life  tabk^s  in  which 


STATISTICS  655 

all  the  members  of  a  liypollu'lieal  populatiDii  are  traced  through 
life,  while  the  mean  age  at  death  is  a  calculation  based  upon  the 
actual  registered  deaths  in  a  population  disturbed  by  fluctuations 
of  both  immigration  and  emigration.  Life  tables  show  how  many 
of  a  given  number  born  live  through  each  year  of  age,  and  what 
is  the  sum  of  the  number  of  years  they  live;  the  sum  of  these 
years  divided  by  the  lives  is  the  mean  duration  of  life  (mean 
after-hfetime  at  birth  or  expectation  of  life  at  birth).  It  is  not 
the  same  thing  as  the  probable  duration  of  life,  which  is  the  age  at 
which  a  given  number  of  children  born  at  the  same  time  are 
reduced  one-half;  the  chances,  therefore,  of  their  dying  before 
or  after  that  age  being  equal.  The  mean  duration  of  life  for 
males  (English  life  table,  1891-1900)  was  44-13  years,  whilst  the 
probable  duration  of  life  was  about  53  years. 

Mean  after-lifetime  is  a  more  accurate  expression  than  expec- 
tation of  life,  as,  strictly  speaking,  the  time  which  it  is  expected 
a  person  will  live  is  the  time  which  it  is  an  even  chance  he  will 
live:  it  is  then  strictly  the  probable  duration  of  his  life. 
But  it  has  been  thought  advisable  to  retain  here  the  term 
"  expectation  of  life,"  as  being  the  term  usually  employed  in 
life  tables.^  It  must  be  understood,  however,  to  mean,  when- 
ever expressed,  the  mean  after-lifetime,  and  not  the  probable 
duration  of  life. 

It  has  been  shown  by  the  late  Professor  de  Chaumont  that  the 
mean  duration  of  life  may  be  approximately  calculated  from  the 
birth  rate  and  death  rate  by  the  following  formula:  where  b  = 
birth  rate  per  unit  of  the  population,  and  d=  death  rate  per  unit 
of  the  population. 


Then  mean  duration  of  life=  \ 


(2        I  )        ( 1        I 
3        ^J         [3         b 


This  formula,  however,  is  really  only  applicable  when  the  birth 

rates  do  not  depart  much  from  the  average  of  the  whole  country. 

Dr.  Tatham  has  shown  how  a  figure,  representing  what  he 

terms  "  life  capital,"  can  be  obtained  with  the  assistance  of  a  life 

table.     If  the  most  recent  mortality  returns  for  a  single  year  are 

compared  with  the  mean  of  those  obtained  for  a  succession  of  the 

years  immediately  preceding,  the  comparison  will  generally  be 

a  favourable  one  to  the  most  recent  year.     The  difference  in  the 

^  The  English  Life  Table  for  1 891-1900  and  many  earlier  life  tables 
will  be  found  in  the  Supplement  to  the  65th  Annual  Report  of  the  Registrar- 
General  (Part  I.). 


656  HYGIENE   AND   PUBLIC   HEALTH 

number  of  deaths  will  be  the  lives  saved  to  the  community.  If 
each  life  gained  be  multiplied  by  the  mean  expectation  of  life  for 
the  corresponding  age-period,  we  obtain  the  gain  of  life  capital 
for  the  community  for  each  age-period,  and  from  this  the  gain 
for  the  whole  community  can  be  ascertained. 

Life  tables  not  only  furnish  the  mean  duration  of  life  or  the 
expectation  of  life  at  birth,  but  also  the  Mean  after-lifetime 
or  the  expectation  of  life  at  any  age — that  is,  the  length  of  time 
a  person  of  any  age  may  be  expected  to  live.  The  expectation 
of  life  at  any  age  is  calculated  from  the  numbers  living  at  the 
age  in  question  and  from  the  years  of  life  they  subsequently  live, 
just  as  is  the  mean  duration  of  life  (expectation  of  life  at  birth). 
For  ages  between  twenty-five  and  seventy-five,  Willich's  formula 
also  gives  approximate  results. 

Ifx=^  expectation  of  life,  and  a=  present  age,  then  x=^'i  {80  — a). 
Life  tables  afford  an  excellent  test  of  the  health  of  a  community. 
By  the  English  table  for  1891-1900,  the  expectation  of  life  at  birth 
for  males  is  44-13  years;  whereas  it  was  43-66  by  the  table  of 
1881-90,  and  39-91  by  the  1834-54  table.  Among  females,  the 
expectation  of  life  was  41-85  and  47-18,  respectively,  in  the  two 
earlier  tables,  and  47-77  by  the  new  table.  The  expectation  of 
life  increases  every  year  in  both  sexes  up  to  the  third  year,  when 
it  is  54-26  for  males  and  56-49  for  females,  the  dangers  to  life  of 
the  period  of  infancy  being  then  passed.  Subsequent  to  the 
third  year,  the  expectation  of  life  gradually  decreases  for  each 
year  of  age. 

As  compared  with  the  old  life  table  of  1838-54  the  expectation 
of  life  for  males  by  the  most  recent  table  is  only  higher  up  to 
the  age  of  33  years,  and  beyond  that  age  is  lower.  For  females 
the  most  recent  table  shows  an  expectation  of  life  higher  up 
to  the  age  of  forty-seven,  as  compared  with  the  1838-54  table. 
The  causes  of  this  alteration  in  figures  between  the  newest  and 
oldest  life  tables  appear  to  be  that  by  improved  sanitary  surround- 
ings the  lives  of  infants  and  children  have  been  saved  in  the 
recent  period  which  were  sacrificed  in  the  former,  thus  increasing 
the  expectation  of  life  during  childhood,  youth,  and  early  man- 
hood. After  reaching  adult  age,  males  are  now  subjected  to 
conditions  which  are  not  more  favourable  to  life— probably  less 
so,  from  increased  competition  and  difficulty  in  gaining  a  liveli- 
hood— than  existed  between  1838-54;  and  this,  together  with 
the  fact  that  some  of  the  lives  saved  in  childhood  are  probably 


STATISTICS  657 

unhealthy  ones,  which  would  have  perished  under  the  old  in- 
sanitary conditions,  accounts  for  the  expectation  of  life  being 
now  actually  less  for  adults  over  33  years  of  age  than  formerly. 
Females,  being  less  subject  to  the  adverse  conditions  of  males, 
and  living  more  at  home,  are  likely  to  derive  benefit  from  im- 
proved sanitation  after  reaching  adult  age,  as  is  indeed  plainly 
shown  by  the  life  tables.  After  the  age  of  forty-seven,  however, 
the  unhealthy  female  lives  saved  in  infancy  begin  to  influence 
the  expectation  of  life. 

Although  by  the  male  hfe  table  the  expectation  of  life  after 
33  years  is  less  now  than  fifty  years  ago,  the  numbers  living  at 
each  year  of  age  up  to  81  years  are  greater  by  the  1891-1900 
table  than  by  the  1838-54  table;  after  81  the  numbers  living 
are  less.  By  the  female  life  table  the  numbers  living  up  to  the 
age  of  91  are  greater  by  the  new  than  the  old  table.  It  is  thus 
seen  that  there  has  been  a  great  saving  in  life,  in  recent  years, 
of  males  and  females  up  to  ages  which  embrace  practically  the 
entire  lifetime.  Although  out  of  a  given  number  of  children 
born  more  survive  and  reach  the  later  age  periods  than  formerl3^ 
it  must  not  be  thought  that  individual  life  is  lengthened;  for, 
as  the  life  tables  show,  individual  life  is  shortened  after  reaching 
a  certain  age  in  both  sexes,  the  reduction  in  the  expectation  of 
life  being  due  to  an  increased  mortality  during  the  later  age- 
periods. 

The  death  rates  of  infants  under  one  year,  and  of  children 
under  five  years,  are  most  important,  as  they  afford  very  positive 
evidence  of  the  sanitary  circumstances  of  a  community.  The 
death  rates  of  infants  under  one  year  should  be  stated  as  so  many 
deaths  in  a  year  to  1,000  registered  births,  this  rate  being  known 
as  the  "  rate  of  infantile  mortality."  This  rate  has  the  advantage 
that  it  can  be  computed  with  certainty  from  an  accurate  register 
of  births  and  deaths;  whereas  the  other  death  rates,  except  in 
census  years,  have  to  be  calculated  from  an  estimated  population, 
and  are  not,  therefore,  so  accurate. 

The  rate  of  infantile  mortality  is  liable  to  considerable  fluctua- 
tions year  by  year,  the  fluctuations  being  largely  determined 
by  the  increased  or  diminished  incidence  of  summer  diarrhoea. 
The  rate  in  this  country  furnished  no  evidence  of  any  continuous 
reduction  until  quite  recently,  and  the  deaths  under  one  year 
of  age  still  continue  to  form  some  25  per  cent,  of  the  total  deaths. 

The  chief  registered  causes  of  infantile  mortality  are  as  follows: — 

42 


658 


HYGIENE    AND    PUBLIC    HEALTH 


Debility,  inanition  and  prematurity  of  birth,  diarrhoea  and 
dysentery,  measles  and  whooping-cough,  convulsions,  accidents 
(including  "  overlying  "),  bronchitis  and  pneumonia.  Seventy 
per  cent,  of  the  total  infantile  mortality  is  generally  ascribed 
to  the  above-mentioned  causes.  The  rate  of  infantile  mortahty 
among  illegitimate  children  is  about  double  that  of  children 
born  in  wedlock. 

The  following  table  shows  the  proportion  of  the  total  deaths 
of  infants  under  one  year  of  age  to  i,ooo  births  contributed  by 
various  causes  in  England  and  Wales  in  1910.  The  deaths 
from  premature  birth  and  congenital  defects  (atelectasis,  patent 
foramen  ovale,  cleft  palate,  imperforate  anus,  spina  bifida,  etc.) 
form  26  per  cent,  of  the  total,  and  occur  chiefly  within  four  weeks 
of  birth.  The  percentage  due  to  diarrhoeal  diseases  in  any  year 
will  be  largely  dependent  on  the  temperature  of  July,  August, 
and  September;  whilst  the  percentage  due  to  bronchitis  and 
pneumonia  will  be  governed  by  the  severity  of  the  winter  and 
spring,  and  the  presence  or  absence  of  whooping-cough  and 
measles  in  epidemic  form. 


Proportion  of  Total  Deaths  of  Infants  under  One  Year  of  Age 
contributed  by  various  diseases  to  1 ,000  births. 


Infectious  Diseases  : 

Per  TjOoo 

]irths. 

Scarlet  fever  and  diphtheria 

-     0-3I 

Chicken-pox            .         .         .         . 

.     0'o6 

Measles           .          .          .          .          . 

.     2-09 

Whooping-cough 

•     4-76 

7*22 

Diarrhceal  Diseases 

. 

12-64 

Developmental  and  Wasting  : 

Premature  birth 

•   19-59 

Congenital  defects 

.     6-69 

Starvation               .         .         .         . 

.     0'6i 

Debility  and  wasting 

•    13-61 

Other  Causes  : 
Tubercle 
Syphilis 

NIeningitis  (non-tubercular) 
Convulsions 

Bronchitis  and  pneumonia 
Overlaying 
Other  causes 


40-50 

3-91 
I-I5 
1-64 
9-17 
18-09 
1-50 
9-62 
45-08 


105-44 


STATISTICS  659 

Infantile  mortality  is  usually  highest  in  the  districts  having 
a  very  high  birth  rate;  this  is  probably  due  to  the  fact  that  high 
birtli  rates  occur  in  relatively  poor-class  communities. 

For  England  and  Wales,  in  the  ten  years  1891-1900,  the  mean 
number  of  deaths  of  male  infants  under  one  year  to  1,000  births 
was  168,  of  female  infants  138,  and  of  both  sexes  153.  For 
the  3'ear  1910  the  rate  for  both  sexes  was  only  105,  which  is  the 
lowest  on  record,  the  rate  for  males  being  116,  and  for  females  94. 

The  decline  in  the  infantile  mortality  rate  in  England  and 
Wales  commenced  about  the  year  1900,  and  witli  the  exception 
of  the  year  1904,  has  continued  almost  uninterru])tcdly  to  the 
present  time. 


Inrantile  Mortalitv 

Year.                                                                                   Rate. 

1899 163 

1900 

154 

I9OI 

151 

1902 

133 

1903 

132 

1904 

145 

1905 

128 

1906 

132 

1907 

118 

1908 

120 

1909 

109 

I9IO 

105 

About  one-third  of  the  deaths  of  children  under  one  year  of 
age  occur  during  the  first  month  of  life,  and  about  one-eighth 
during  the  first  week;  about  half  occur  during  the  first  three 
months.  This  circumstance  is  largely  accounted  for  by  un- 
favourable ante-natal  conditions. 

The  deaths  of  children  under  five  should  be  stated  as  death 
rates  per  1,000  living  under  that  age.  The  average  rate  for  male 
children  for  England  and  Wales  1906-10  was  43-5  per  1,000,  for 
female  children  36-0  per  1,000,  and  of  both  sexes  39-8.  No 
doubt  some  part  of  this  infant  and  child  mortality,  which  is 
preventable,  is  due  to  other  causes  than  insanitar}^  conditions 
controllable  by  local  authorities,  such  other  causes  being  maternal 
neglect,  insufficient  and  improper  nourishment,  etc.  Still,  just 
as  a  sustained  rate  of  general  mortality  above  17  for  1,000 
always  implies  unfavourable  sanitary  conditions  (Dr.  Farr),  so  it 
may  be  said  that  rates  of  mortality  amongst  infants  and  young" 
children,  which  exceed  the  rates  prevalent  in  the  country  gener- 
ally, are  mainly  indications  of  bad  sanitary  conditions  in  the 


660  HYGIENE   AND   PUBLIC   HEALTH 

communities  in  which  they  occur,  and  of  ignorance  or  neglect 
on  the  part  of  the  mothers. 

The  importance  of  a  right  use  of  vital  statistics,  and  of  avoiding 
unfounded  and  erroneous  deductions,  is  so  great  that  it  will  be 
well  to  further  indicate  some  of  the  errors  and  fallacies,  which 
are  either  inseparable  from,  or  are  introduced  into  the  subject. 

In  the  first  place,  the  data  derived  from  the  census  returns  are 
incomplete  and  sometimes  fallacious:  e.g.,  old  people  are  often 
ignorant  of  their  precise  age,  and  frequently  overstate  it  when 
very  old;  females  often  wilfully  misstate  their  ages;  and  young 
children  are  often  returned  as  one  or  two  years  old  when  they 
are  only  in  their  first  and  second  years.  Again,  the  population 
is  only  an  estimate  in  the  intercensal  periods,  and  considerable 
errors  in  the  estimation  often  arise;  it  is  for  this  reason  that  a 
five-yearly  census  is  so  much  to  be  desired.  The  registration 
of  births  and  deaths,  and  the  certification  of  the  causes  of  deaths 
are  subject  to  many  fallacies,  arising  from  faulty  diagnosis, 
indefinite  certification,  and  the  lack  of  uniformity  in  the  nomen- 
clature of  disease;  whilst  many  births  escape  certification  from 
ignorance,  shame  of  illegitimacy,  or  from  the  parents'  desire  to 
avoid  vaccination.  The  use  of  such  terms  as  "  convulsions," 
"  jaundice,"  and  "  dropsy,"  for  instance,  should  be  avoided, 
whenever  the  true  cause  of  these  symptoms  can  with  reasonable 
certainty  be  substituted.  It  is  impossible,  also,  to  correctly 
classify  deaths  which  are  returned  as  due  to  two  or  three  distinct 
maladies,  without  any  indication  as  to  which  was  the  primary 
cause  of  death.  Various  classifications  of  deaths  have  been  sug- 
gested and  employed;  they  may  be  based  on  symptoms,  causes, 
the  tissues  and  organs  affected,  or  the  parts  of  the  body  affected 
consi  dered  anatomically.  The  latter  is  the  classification  suggested 
by  Farr  and  Bertillon;  and  it  probably  insures  a  greater  pre- 
cision in  classification,  and  favours  a  more  just  comparison 
\)i  the  deaths  from  various  causes  than  any  other. 

The  Society  of  Medical  Officers  of  Health  has  issued  certain 
ruies  as  to  the  classification  of  causes  of  death.  It  is  advised  as 
a  general  rule  to  select,  when  several  diseases  are  mentioned  in  a 
certificate,  the  disease  of  the  longest  duration,  but  any  one  of  the 
chief  infective  diseases  should  be  selected  in  preference  to  any 
olhcr  cause  of  death;  and  definite  diseases,  ordinarily  known 
as  "  constitutional  diseases,"  should  have  preferencejover  those 
known  as  local  diseases.     When  apoplexy  occurs  in  coni^nction 


STATISTICS  66 1 

with  dcftnitc  disease  of  the  heart  or  kidneys,  the  heart  or  kidney 
disease,  as  the  case  may  be,  shouUl  be  preferred;  and  when 
hemiplegia  is  certified  in  conjunction  with  embohsm,  the  embohsin 
should  be  selected.  Diarrhoea  should  be  ascribed  as  the  cause  of 
death  only  when  mentioned  alone  or  in  connection  with  some 
other  indehnite  cause,  such  as  convulsions,  teething,  marasmus, 
etc.  In  addition  to  deaths  ascribed  to  diarrhoea  alone  or  as 
above  indicated  in  the  certificate,  deaths  from  intestinal  catarrh, 
epidemic  enteritis,  or  zymotic  enteritis,  should  be  included  under 
diarrhoea.  But  deaths  from  gastric  catarrh,  as  well  as  from  gastro- 
enteritis and  enteritis  (without  the  prefix  epidemic  or  zymotic), 
should  be  excluded.  The  Registrar-General,  however,  is  now 
including  all  deaths  from  diarrhoea  and  enteritis  in  children 
and  adults  under  one  heading. 

The  death  rate  of  seaside  places  is  seldom  correct.  A  certain 
number  of  visitors  are  always  included  in  the  estimation  of  the 
population,  and  it  is  not  easy  to  exclude  their  deaths.  The 
domestic  servants  in  a  community  introduce  a  further  fallacy 
in  vital  statistics,  since  they  rarely  die  in  service.  Although 
counted  in  the  population  of  the  district  where  they  reside,  they 
frequently  return  to  their  homes  in  rural  districts,  when  seriously 
ill  and  unfit  for  further  service. 

The  death  rates  of  general  hospitals  can  never  be  justly  com- 
pared, because  of  the  varying  nature  and  gravity  of  the  cases 
admitted  from  time  to  time,  the  varying  proportion  of  medical  to 
surgical  beds,  etc.  The  death  rate  is  often  stated  as  the  number  of 
deaths  to  every  loo  occupied  beds,  but  it  is  better  to  express  the 
deaths  as  a  ratio  of  the  number  of  cases  treated  to  a  termination. 

Occupation  plays  an  important  part  in  determining  mortality, 
some  occupations  being  far  more  healthy  than  others.  Occupa- 
tional mortality  is  calculated  from  the  deaths  occurring  in  any 
particular  occupation.  For  purposes  of  comparison  the  death 
rates  among  those  employed  at  corresponding  age-periods  must 
be  taken,  allowance  being  thus  made  for  the  varying  age  constitu- 
tion of  those  engaged  in  the  different  occupations.  A  comparative 
mortality  figure  for  different  occupations  may  be  obtained  by 
taking  the  deaths  occurring  in  a  standard  population,  such  standard 
population  to  consist  of  the  exact  number  of  males  in  the  whole 
population  between  twenty-five  and  sixty-five  years  of  age,  who 
would  supply  1,000  deaths  annually.  Dealing  with  the  deaths 
of  1890-2  and  the  population  of  1891,  Dr.  Tatham  showed  that 


662 


HYGIENE   AND   PUBLIC   HEALTH 


1,000  deaths  occurred  among  61,215  males  between  twenty-tive 
and  sixty- five  years  of  age ;  whereas  the  number  of  deaths  among 
a  similar  number  of  medical  practitioners  only  amounted  to  966 ; 
or,  in  other  words,  the  same  number  of  men  aged  twenty-five 
to  sixty-five  (having  equal  numbers  at  the  various  inclusive  ages) 
that  would  furnish  1,000  deaths  among  all  males,  would  only  give 
966  among  medical  practitioners. 

Exaynple : — 


A^es. 


Standard 
Population. 


Dtatli  Rate  per  i  ,000  Living 
ill  Each  Group  among — 


Calculated  Number  of 
Deaths  in  Standard  Popu- 
lation among — 


25-35 

35-45 

45-55 
SS-6S 


22,586 
17,418 
12,885 
8,326 
61,215 


All  Males. 

7-67 
13-01 

21-37 
39-OI 


Medical 
Practitioners 


All  Males. 


Medical 
Practitioners. 


6-69 
14-92 
21-04 

34-16 


173 

227 

275 
325 


1,000 


151 
260 
271 
284 
966 


An  obvious  fallacy  in  any  attempt  to  gauge  the  relative  healthi- 
ness of  different  occupations  results  from  the  fact  that  certain 
occupations  attract  the  more  robust  and  muscular,  whilst  others 
demanding  less  strength  attract  the  weakhngs. 

The  mean  age  at  death  cannot  be  taken  as  an  index  of  the 
healthiness  of  an  occupation,  because  some  employments  are 
filled  by  older  men,  who  have  proved  their  worth  or  have  filled 
minor  posts  during  many  years,  while  other  classes  of  labour 
requiring  less  skill  and  experience  are  much  more  largel}^  filled 
by  those  young  in  life. 

Instances  of  the  more  usually  employed  graphic  methods  of 
representing  statistical  results  can  be  seen  in  the  annual  reports 
of  medical  officers  of  health.  Erroneous  conclusions  are  apt  to 
be  formed  by  comparing  the  mortality  curves  on  scales  which 
are  not  identical.  "  Spot  maps  " — maps  of  the  district,  on 
which  the  deaths  or  cases  of  various  infectious  diseases  are 
indicated  on  the  locality  where  they  occur — furnish  valuable 
graphic  expressions  of  any  grouping  of  such  deaths  or  sickness, 
and  are  much  employed  by  medical  officers  of  health.  They 
should,  however,  usually  be  employed  to  express  these  occurrences 
for  short  periods  only.  Spot  maps,  covering  a  period  of  several 
months  or  a  year,  are  not  often  of  much  value  for  the  purpose 
which  they  are  designed  to  subserve. 


CHAPTER  Xril 


SANITARY  LAW  AND  ADMINISTRATION 

Sanitary  Areas  and  Authorities. 

By  the  Local  Government  Act,  1 894,  England  and  Wales  are  divided  into 
—  (i)  administrative  counties,  (2)  county  boroughs.  The  administrative 
counties  are  divided  into  urban  and  rural  districts  with  the  exception  of  the 
County  of  London,  which  is  divided  into  twenty-eight  Metropolitan 
Boroughs. 

The  following  table  shows  the  areas,  the  authorities,  and  the  chief  Acts 
having  relation  to  public  health  which  the  sanitary  authorities  administer: 


Administrative 
County 


County  Borough 
Municipal 

Borough 
Urban  District 
(of  County) 


Auiliority. 


County  Council 


Town  Council 
Municipal 

Council 
Urban  District 
Council. 


Sanitary  Acts  Administered. 


Appeal  Authority  under  Local  Go- 
vernment Act,  1894,  and  under 
sec.  299,  Public  Health  Act,  1875. 
Rivers  Pollution  Prevention  Act, 
1876.  Isolation  Hospitals  Act, 
1893.     Midwives  Act,  1902. 

Local  Sanitary  Acts.  Public  Health 
Act,  1875.  Public  Health  Acts 
Amendment  Act,  1890  (adop- 
tive). Public  Health  Acts 
Amendment  Act,  1907  (adoptive 
by  an  Urban  Sanitary  Authority, 
an  Urban  District  Council,  or  a 
Rural  District  Council).  Sale  of 
Food  and  Drugs  Acts,  1875, 
1 879,  and  1 899.  Margarine  Act, 
1887.  The  Sale  of  Horseflesh 
Act,  1889.  Canal  Boats  Acts, 
1877,1884.  Public  Health  Inter- 
ments Act,  1879.  Factories  and 
Woi-kshops  Act,  1 90 1,  so  far  as 
relates  to  sanitation.  Housing 
of  the  Working  Classes  Act, 
1890,  1899.  The  Housing  and 
Town  Planning  Act,  1909.  In- 
fectious Diseases  Notification 
Act,  1889.  Infectious  Diseases 
Prevention  Act,  1890  (adoptive). 
Dairies,  Cowsheds,  and  INIilk- 
shops  Orders,  1885,  1886,  1899. 
Rivers  Pollution  Prevention  Act, 
1 876.  The  Cleansing  of  Persons 
Act,  1897.  The  Notification  of 
Births  Act,  1907  (adoptive). 


663 


664 


HYGIENE   AND    PUBLIC   HEALTH 


Area. 

Authority. 

Sanitary  Acts  Administered. 

Rural  District 

Rural  District 

I 
All  the  Acts  above  cited  as  ad- 

(of County) 

Council 

ministered   by   Urban   Sanitary 
Authorities,  with  the  exception 
of  certain  sections  of  the  Public 
Health  Act,  1875,  and  of  Part  L   ! 
of  the  Housing  of  the  Working 
Classes    Act.        Public    Health  , 
(Water)  Act,  1878. 

Parisli,    forming 

Parish    Council 

Certain  sanitary  powers  under  the 

part  of  a  Rural 

Local    Government    Act,    1894, 

District 

section  8,  but  not  in  substitution 
of  those  exercised  by  the  Rural 
District  Council. 

Port 

Port  Sanitary 

Assigned  by  the  Local  Government 

Authority 

Board,  and  practically  those  of 
an   Urban   Sanitary   Authority. 
Regulations  of  the  Local  Gov- 
ernment   Board.        The    Public 
Health  (Ships)  Act,  1885. 

County  of  London 

London  County 

The  MetropoUs  Local  Management 

Metropolitan 

Council 

Acts,    Public   Health    (London) 

Boroughs 

Borough 

Councils 

Act,  1 891,  etc. 

Port  Sanitary  Authorities. 

Under  the  Public  Health  Act,  1875,  section  z?>7,  the  Local  Government 
Board  may  by  Order  constitute  any  sanitary  authority,  or  a  combination 
of  sanitary  authorities,  whose  district  or  districts  abut  upon  any  port  in 
England  or  Wales,  the  port  sanitary  authorit}' — either  temporarily  or 
permanently.  The  Order  may  assign  to  the  port  sanitary  authority  any 
of  the  powers,  duties,  etc.,  of  an  urban  sanitary  authority,  so  far  as  applic- 
able to  a  port,  and  to  vessels,  waters,  or  persons  within  its  jurisdiction. 
These  duties  include  the  appointment  of  a  medical  oflicer  of  health  and  of 
an  inspector  of  nuisances,  the  duties  of  the  former  being  prescribed  by  a 
special  Order  of  the  Local  Government  Board.  In  addition,  this  officer 
has  to  carry  out  the  Board's  Cholera  Regulations  of  1890  and  1892,  and  any 
Regulations  made  by  the  Board  prohibiting  the  importation  of  rags  from 
infected  foreign  ports,  or  requiring  that  they  shall  be  disinfected  or 
destroyed  to  the  port  medical  officer's  satisfaction  (1893  Order).  The 
disinfection  must  be  by  steam.  Dirty  and  disused  bedding  or  clothing 
arriving  from  certain  ports,  whether  belonging  to  emigrants  or  otherwise, 
can  only  be  landed  for  destruction  or  disinfection. 

A  port  sanitary  authority  discharges  duties  under  public  health 
legislation,  which  are  very  similar  to  those  performed  by  urban  sanitary 
authorities.  The  port  sanitary  authority  has  not  full  control  in  matters 
affecting  the  sanitation  of  vessels,  as  the  sanitary  provisions  of  the  Merchant 
Shipping  Act,  1894,  are  not  administered  by  them,  and  ships  belonging  to 
British  and  Foreign  Governments  are  exempt  from  their  inspection. 

The  port  sanitary  authority  exercises  its  powers  under  the  following 
Acts,  Orders,  etc.:  (i)  The  Public  Health  Act,  1875,  and  the  Public  Health 
(London)  Act,  1891,  under  which  any  ship  or  vessel  lying  in  any  river, 
harbour,  or  other  water  within  the  district  of  the  local  authority,  is 
subject  to  the  same  treatment  with  regard  to  nuisances,  as  premises  on 


SANITARY    LAW    AND    ADMINISTRATION  665 

land;  (2)  the  Public  Health  (Ships)  Act,  1885,  which  extends  to  ships  the 
provisions  of  the  Public  Health  Act,  1875,  which  apply  to  hospitals  and 
infectious  disease;  (3)  the  provisions  of  the  Infectious  Diseases  Notifica- 
tion Act,  1889,  which  are  applicable  to  ships;  (4)  the  Public  Health  Act, 
1 896,  which  repeals  the  Acts  relating  to  quarantine,  and  defines  the  powers 
of  the  Local  Government  Board  to  make  Regulations  (under  the  Public 
Health  Act,  1875)  as  to  cholera,  yeUow  fever,  and  plague  as  follows: — 
(a)  Signals  to  be  hoisted  by  vessels  having  such  diseases  on  board ;  (b)  ques- 
tions to  be  answered  by  masters,  pilots,  and  passengers  as  to  cases  of  disease 
on  board  during  the  voyage;  (c)  the  detention  of  vessels  and  persons 
aboard;  {d)  certain  duties  to  be  performed  by  the  master,  pilot,  etc. 

These  Regulations  (1896)  also  require  that  infected  ships  must  hoist  a 
yellow  and  black  Hag,  which  must  be  displayed  between  sunrise  and  sunset 
when  within  three  miles  of  the  coast.  Under  the  existing  Regulations 
"  Every  ship  is  deemed  to  be  infected  in  which  there  is  or  has  been  during 
the  voyage,  or  during  the  stay  of  such  a  ship  in  the  port  of  departure,  or 
in  a  port  in  the  course  of  such  voyage,  any  case  of  cholera,  yellow  fever 
or  plague,"  and  the  term  "  cholera "  includes  "  choleraic  diarrhoea." 
Under  the  Paris  Convention,  1903,  infected  ships  are  those  where  there 
has  been  any  case  of  cholera  or  plague  on  board  within  seven  days  of 
arrival  in  port.  Suspected  ships  are  those  where  there  have  been  any 
cases  of  cholera  or  plague  on  board  at  the  time  of  departure,  or  during  the 
voyage,  but  no  fresh  cases  within  seven  days.  A  place  must  be  appointed 
for  the  mooring  of  all  infected  ships,  and  when  the  Customs  Officer  finds 
or  suspects  that  a  ship  is  infected  he  must  order  the  ship  to  be  anchored 
in  this  place  and  acquaint  the  sanitary  authority  of  the  fact,  when  none 
of  the  passengers  or  crew  may  leave  the  ship;  the  medical  officer  of  health 
must  visit  and  inspect  within  twelve  hours,  or  the  ship  may  proceed;  and, 
if  he  is  of  opinion  that  any  ship  is  infected,  he  must  certify  to  the  master 
of  the  ship  and  the  sanitary  authority  and  inform  the  Local  Government 
Board;  the  master  must  moor  to  an  appointed  "mooring  place,"  where 
the  medical  officer  of  health  shall  examine  every  person  on  board;  and 
no  one  may  leave  the  ship. 

Infected  persons  must  be  removed  to  a  hospital,  or  the  ship  may  be 
constituted  the  hospital;  suspected  persons  may  be  detained  on  board 
or  in  hospital  for  forty-eight  hours ;  other  persons  shall  satisfy  the  medical 
officer  as  to  their  names,  places  of  destination  and  addresses  at  such 
places,  and  the  clerk  to  the  sanitary  authority  must  transmit  this  informa- 
tion to  the  sanitary  authorities  of  the  districts  to  which  such  persons  are 
going;  every  person  who,  within  forty-eight  hours  after  landing,  shall 
arrive  at  any  other  address  than  that  furnished,  must  notify  in  writing 
his  fresh  address  to  the  medical  officer  of  health  of  the  district  in  which 
such  place  is  situate. 

The  master,  under  the  direction  of  the  sanitary  authority,  must  bury 
infected  dead  bodies  (properly  loaded)  at  sea,  or  deliver  to  sanitary 
authority  for  burial;  all  necessary  disinfection  is  to  be  carried  out  at  the 
cost  of  the  owner  and  to  the  satisfaction  of  the  medical  officer  of  health ; 
where  a  ship  comes  from  a  place  infected  with  cholera,  yellow  fever  and 
plague  (though  not  itself  infected),  or  has  filthy  and  unwholesome  persons 
on  board,  the  medical  officer  of  health  may  issue  certificates  (one  to  the 
sanitary  authority  and  one  to  the  master)  to  prevent  the  landing  of  such 
persons  until  they  satisfy  the  medical  officer  as  to  their  names  and  addresses 
at  places  of  destination;  bilge  water,  and  water  that  may  be  ordered  to 
be  pumped  out  before  the  ship  (whether  infected  or  from  an  infected  port) 
enters  a  dock  or  basin,  and  all  casks  or  tanks  containing  drinking  water 
are  to  be  emptied  and  cleansed  if  required. 

If  any  person  wilfully  neglects  or  refuses  to  obey  or  carry  out  or  obstructs 


666  HYGIENE    AND   PUBLIC    HEALTH 

the  execution  of  any  of  these  regulations,  he  is  liable  to  a  penalty  not 
exceeding  ;^ioo  and  ^50  for  each  day  of  continuing  offence. 

An  International  Conference  was  held  at  Paris,  1903,  and  a  Convention 
was  agreed  to  dealing  with  the  precautions  to  be  adopted  to  prevent  the 
introduction  of  cholera,  yellow  fever,  and  plague. 

On  ships  infected  with  plague,  the  rats  must  be  destroyed  either  before 
or  after  the  discharge  of  cargo,  within  a  maximum  period  of  forty-eight 
hours.  Precautionary  measures  shall  be  adopted  at  infected  ports  on 
the  departure  of  vessels  ;  and  the  Local  Government  Board  has  made 
regulations  as  to  this. 

For  the  purpose  of  administering  these  powers  the  port  sanitary  autho- 
rity shall  appoint  a  medical  officer  of  health  and  sanitary  inspectors. 
In  a  large  port  the  services  of  one  or  more  assistant  medical  officers  are 
generally  required,  especially  when  cholera  or  plague  threatens;  the 
medical  officers  then  take  duties  in  rotation. 

In  the  sanitary  inspection  of  ships  the  following  matters  claim  atten- 
tion:— The  condition  of  the  crew's  quarters  with  regard  to  ventilation, 
lighting,  cleanliness,  and  protection  from  weather;  cubical  capacity  and 
floor  areas  (there  should  be  a  minimum  of  jz  cub.  ft.  and  12  sq.  ft.  of  floor 
space  for  each  man)  1 ;  general  cleanliness ;  the  efficiency  of  sanitary  fittings 
and  the  condition  of  the  bilges  and  bilge-water;  the  source  of  supply  and 
storage  of  drinking-water,  the  accessibihty  for  cleansing  purposes  and  the 
protection  of  tanks,  etc.,  from  contamination.  The  inspection  of  food- 
stuffs brought  to  the  port,  and  their  seizure  when  unwholesome  or  unfit 
for  the  food  of  man,  is  an  important  branch  of  port  sanitary  work. 

The  work  of  checking  the  spread  of  infectious  disease  aboard  and  pre- 
venting its  importation  is  another  important  branch  of  work.  It  is 
performed  in  precisely  the  same  manner  as  on  shore,  as  is  also  the  subse- 
quent disinfection.  Copies  of  the  regulations  relating  to  various  infectious 
diseases  are  printed  in  several  languages  and  distributed  among  ship- 
owners, consuls,  captains  and  all  interested. 

By-laws  relating  to  infectious  diseases  have  been  made  by  nearly  all 
port  sanitary  authorities.     These  require  inter  alia  that: 

A  vessel  arriving  with  any  person  on  board  suffering  from  a  dangerous 
infectious  disorder  is  required  to  stop  at  a  certain  specified  place, 
and  acquaint  the  medical  officer  of  health.     The  vessel  shall  remain 
there  until  boarded  by  the  medical  officer  of  health,  who  may  order 
the  master  to  land  the  case  at  the  hospital  of  the  port  sanitary  autho- 
rity, if  proper  accommodation  can  be  provided  therein. 
By-laws  may  also  be  made  for  keeping  in  hospital,  for  so  long  as  may  be 
necessary,  any  persons,  brought  within  their  district  by  any  vessel,  who 
are  infected  with  a  dangerous  infectious  disease. 

As  the  Customs  Officers  are  the  first  to  receive  intimation  of  sickness 
on  board  any  vessel  approaching  the  port,  it  is  desirable  that  the  Customs 
Depot  and  the  Port  Sanitary  Offices  should  be  adjacent  to  each  other,  so 
that  all  information  of  infectious  illness  can  be  easily  and  promptly  re- 
ported to  the  sanitary  authority.  The  Port  Sanitary  Hospital  should  be 
well  isolated  and  at  a  convenient  distance  from  the  mooring  station. 
Commonly  the  City  Fever  Hospital  is  used  for  the  reception  of  all  sea- 
borne cases  of  infectious  disease  excepting  cholera,  plague,  yellow  fever 
or  small-pox. 

In  connection  with  plague-infected  ships,  every  effort  must  be  made  to 
prevent  rats  from  landing  and  to  destroy  them  so  far  as  possible.  The 
employment  of  an  experienced  rat-catcher  appears  to  be  tlie  best  solution 


^  These  measurements  have  been  increased  by  the  Merchant  Shipping 
Act,  1906,  to  120  cubic  feet  and  15  superficial  feet  respectively. 


SANITARY    LAW    AND    ADMINISTRATION  667 

of  this  dilliculty.  The  rats  caught  alive  on  board  should  be  killed  and, 
with  the  bodies  of  those  found  dead,  destroyed  in  the  ship's  furnaces. 

When  any  vessel  has  had  dangerous  infectious  disease  aboard,  the  medical 
officer  of  health  must  give  notice  to  the  medical  officer  of  health  thereof 
of  any  port  in  the  United  Kingdom  whither  such  vessel  is  about  to  sail. 

The  Canal  Boats  Act,  1877  and  1884,  and  the  Regulations  made  under 
these,  are  also  administered  by  certain  port  sanitary  authorities. 

Ship-Borne  Rats  and  Plague. 

In  view  of  the  susceptibility  of  the  rat  to  plague,  and  of  risk  therefore 
of  importation  into  this  country  by  shipping  of  plague-infected  rats, 
sanitary  authorities  of  seaports  should  be  on  the  alert  to  prevent  intro- 
duction of  the  disease  into  their  districts  in  this  way. 

1.  On  the  arrival  in  port  of  a  vessel  whereon,  during  the  voyage,  plague 
or  sickness  suspected  to  be  plague  has  occurred,  measures  should  be  taken 
to  secure  the  destruction  of  the  rats  on  board  the  vessel.  Until  this  has 
been  done,  endeavour  should  be  made  to  prevent  rats  leaving  the  sliip,  by 
mooring  the  vessel  a  sufficient  distance  from  other  ships  and  from  the  shore, 
and  by  placing  guards  on  cables  and  hawsers  in  use  for  mooring  purposes. 

2.  In  the  case  of  vessels  that  have  come  from  places  infected  with  plague, 
but  on  board  of  which  no  plague  or  suspected  plague  has  occurred,  strict 
inquiry  should  be  made  on  their  arrival  in  port  as  to  mortality  or  sickness 
among  rats  during  the  voyage.  Should  this  have  occurred,  the  authority 
would  do  well  to  obtain  the  body  of  a  sick  rat  for  the  purpose  of  ascertaining 
the  nature  of  the  malady  affecting  those  animals  on  board  the  vessel.  In 
the  event  of  the  malady  being  found  to  be  plague,  the  ship  should  be  dealt 
with  as  under  Paragraph  i. 

3.  Exceptional  sickness  or  mortality  among  rats  on  board  any  vessel 
within  the  district,  whatever  may  have  been  her  port  of  departure,  should 
be  viewed  with  suspicion  and  as  giving  occasion  for  action  similar  to  that 
indicated  under  Paragraph  2. 

4.  Rats  when  destroyed  on  shipboard  should  not  be  handled;  they 
should  be  at  once  cremated. 

5.  In  the  event  of  rats  on  board  any  ship  being  found  to  be  infected  with 
plague,  all  parts  of  the  vessel  frequented  by  those  animals  should,  as  far 
as  possible,  be  disinfected. 

6.  The  authorities  of  seaport  towns  invaded  by  plague  should  endeavour 
to  secure  the  destruction  of  the  rats  of  the  town,  not  least  those  inhabiting 
the  docks  and  quayside  warehouses.  Measures  should  be  taken  to  guard 
against  shore-rats  making  their  way  on  board  vessels  lying  in  the  port, 
and  an  attempt  made  to  destroy  all  rats  on  board  ships  about  to  proceed  on 
their  voyage.  Captains  of  such  vessels  should  be  urged  to  teike  steps  during 
the  ensuing  voyage  for  the  destruction  of  rats  that  may  have  remained 
alive  on  board  their  vessels  notwithstanding  the  action  of  the  local 
authority. 

The  Local  Government  Board  has  also  published  (August  26,  1892)  a 
set  of  Precautions  against  the  Infection  of  Cholera,  a  General  Memorandum 
on  the  Proceedings  which  are  advisable  in  Places  attacked  or  threatened  by 
Epidemic  Disease,  and  a  Memorandum  on  Plague. 

The  Aliens  Act,   1905. 

Immigrants  may  not  be  landed  in  the  United  Kingdom  from  an  immi- 
grant ship  except  at  a  port  at  which  there  is  an  immigration  officer  aj)- 
pointed  under  the  Act,  and  may  not  land  at  any  such  port  unless  first 
inspected  by  such  officer  in  company  with  a  medical  inspector,  such 
inspection  to  be  made  as  soon  as  practicable. 


668  HYGIENE   AND   PUBLIC   HEALTH 

Leave  to  land  may  be  withheld  in  the  case  of  undesirable  immigrants, 
but  the  master,  owner,  or  agent  of  the  ship  or  the  immigrant  may  appeal 
to  the  immigration  board  of  the  port,  and  the  board,  if  satisfied  that  leave 
to  land  should  not  be  withheld,  may  grant  leave. 

An  undesirable  immigrant  is  one  who  cannot  show  that  he  has  in  his 
possession  or  is  in  a  position  to  obtain  the  means  of  decently  supporting 
himself  and  his  dependants  (if  any) ;  or  if  he  is  a  lunatic  or  an  idiot,  or 
owing  to  any  disease  or  infirmity  appears  likely  to  become  a  charge  upon 
the  rates  or  otherwise  a  detriment  to  the  public;  or  has  been  sentenced 
in  a  foreign  country  with  which  there  is  an  extradition  treaty,  for  a  crime, 
not  being  an  offence  of  a  political  character;  or  if  an  expulsion  order  under 
this  Act  has  been  made  in  his  case. 

In  the  case  of  immigrants  who  prove  that  they  are  seeking  admission  to 
this  country  solely  to  avoid  persecution  or  punishment  on  religious  or  poli- 
tical grounds,  or  for  political  offences,  leave  to  land  must  not  be  refused  on 
the  ground  of  want  of  means,  or  the  probability  of  their  becoming  a  charge 
on  the  rates.  The  same  applies  to  immigrants  who  having  resided  six 
months  in  this  country  have  been  refused  admission  to  a  foreign  country, 
and  return  direct  therefrom,  and  to  those  who  were  born  in  the  United 
Kingdom,  and  are  British  subjects. 

The  Secretary  of  State  may,  if  he  thinks  fit,  in  respect  of  any  alien 
certified  to  be  convicted  by  any  court  of  any  felony,  misdemeanour,  or 
other  offence  punishable  by  imprisonment  without  the  option  of  a  fine, 
make  an  expulsion  order  requiring  the  alien  to  leave  the  United  Kingdom 
within  a  fixed  time,  and  thereafter  to  remain  out  of  the  United  Kingdom. 

Medical  Officers  of  Health  and  Sanitary  Inspectors. 

By  the  Public  Health  Act,  1875,  section  189,  every  urban  and  rural 
sanitary  authority  is  required  to  appoint  a  medical  officer  of  health  and 
an  inspector  of  nuisances;  but  two  or  more  districts  may  be  combined 
by  the  Local  Government  Board  to  form  a  combined  sanitary  district, 
with  one  set  of  officers  for  the  whole  combination.  County  Councils  under 
the  Local  Government  Act,  1888,  section  17,  may  appoint  a  county  medical 
officer  of  health. 

If  any  part  of  the  salary  of  a  medical  officer  of  health  is  repaid  to  a 
local  authority  out  of  Imperial  funds,  the  Local  Government  Board  has 
the  same  power  of  approval  of  his  qualifications,  appointment,  duties, 
salary,  and  tenure  of  office,  as  it  has  in  the  case  of  a  poor  law  medical 
officer  (Public  Health  Act,  1875,  section  191). 

By  section  18  of  the  Local  Government  Act,  1888,  every  medical  officer 
of  health  appointed  after  the  passing  of  the  Act  must  be  legally  qualified 
in  medicine,  surgery,  and  midwifery;  if  appointed  after  January  i,  1892, 
to  a  district  having  at  the  last  census  50,000  inhabitants  or  more,  he 
must  be  the  registered  holder  of  a  diploma  in  public  health  under  sec- 
tion 21  of  the  Medical  Act,  1886,  or  have  been  during  three  consecutive 
years  prior  to  1892  a  medical  officer  of  health  of  a  district  with  a  popu- 
lation at  the  last  census  of  not  less  than  20,000,  or  have  been  for  not  less 
than  three  years  a  medical  officer  or  inspector  of  the  Local  Government 
Board. 

If  no  part  of  the  salary  of  the  medical  officer  of  health  is  repaid  to  the 
sanitary  authority,  the  Local  Government  Board  need  not  be  consulted, 
nor  is  their  approval  necessary  as  regards  qualifications,  appointment, 
salary,  or  tenure  of  office.  If  a  portion  of  the  salary  is  repaid,  the  medical 
officer  cannot  be  removed  except  with  the  sanction  of  the  Board,  and 
if  suspended  the  Board  may  remove  the  suspension.  The  duties  of  both 
classes  of  officers  are  the  same  under  the  Local  Government  Board's 
regulations  of  March  23,  1891. 


SANITARY   LAW    AND    ADMINISTRATION  669 

In  London  every  medical  officer  of  health  must  reside  within  his  district 
or  within  one  mile  of  its  boundary.  He  must  not  be  appointed  for  a 
limited  period  only,  as  may  be  done  outside  London.  He  is  removable 
by  the  Local  Government  Board,  as  well  as  by  his  sanitary  authority, 
with  the  consent  of  the  Local  Gt)vernment  Board.  In  other  respects  the 
post  is  similar  to  that  of  an  extra  Metroj^olitan  officer  as  regards  appoint- 
ment, qualiiications,  tenure  of  office,  and  duties. 

In  London  every  sanitary  inspector  appointed  after  January  i,  1895, 
must  be  a  holder  of  a  certificate  of  an  examininj,'  board  approved  by  the 
Local  Government  Board,  or  must  have  been  during  three  consecutive 
years  preceding  1895  an  inspector  of  a  district  containing  a  population  of 
not  less  than  20,000.  Outside  London  there  is  no  qualification  required 
by  statute  for  inspectors  of  nuisances. 

In  London  every  sanitary  authority  is  required  to  appoint  an  adequate 
number  of  fit  and  proper  persons  as  sanitary  inspectors;  and  the  London 
County  Council  has  power  to  insist  upon  a  sufficiency  of  inspectors  for 
each  Metropolitan  Borough. 

By-Laws  and  Regulations. 

Under  the  various  statutes  relating  to  public  health,  sanitary  authorities 
have  power  to  make  by-laws.  These  by-laws  should  supplement,  not  vary 
or  supersede,  the  express  provisions  of  the  statutes.  If  repugnant  to  the 
laws  of  England  or  to  the  provisions  of  the  Acts,  they  are  ttlira  vires  and 
of  no  effect.  Reasonable  penalties  may  be  provided  for  in  the  by-laws  for 
neglect  or  infringement  of  their  requirements.  All  by-laws  must  be  con- 
firmed by  the  Local  Government  Board,  and  when  so  confirmed  have  the 
force  of  law.  Regulations  do  not,  as  a  rule,  provide  for  the  infliction  of 
penalties,  nor  require  confirmation  by  the  Local  Government  Board. 
Both  by-laws  and  regulations  are  usually  drafted  upon  models  issued  by 
the  Local  Government  Board. 

Every  urban  sanitary  authority  must  make  by-laws  in  respect  of  common 
lodging  houses  and  slaughter  houses,  and  every  rural  sanitary  authority 
must  make  by-laws  in  respect  of  the  former.  With  respect  to  all  other 
matters  on  which  by-laws  may  be  made,  it  is  optional  to  do  so,  unless 
required  by  the  Local  Government  Board.  Both  urban  and  rural 
authorities  may  make  by-laws  in  respect  of  cleansing  and  scavenging; 
tenement  houses  occupied  by  members  of  more  than  one  family ;  hop  and 
fruit  pickers;  tents  and  vans;  and  mortuaries.  Urban  authorities  may 
in  addition  make  by-laws  for  new  streets  and  buildings,  markets  and  fairs, 
offensive  trades,  open  spaces,  and  cemeteries.  Urban  powers  may  be 
granted  by  the  Local  Government  Board  to  rural  authorities,  including 
the  making  of  by-laws;  and  the  adoption  of  the  Public  Health  Acts 
Amendment  Act,  1890,  enables  a  rural  authority  to  make  certain  by-laws 
in  respect  of  new  and  old  buildings. 

Regulations  may  be  made  by  any  sanitary  authority  under  the  Dairies, 
Cowsheds,  and  Milkshops  Order  with  respect  to  dairies  and  cowsheds; 
also  under  the  Public  Health  Act,  1875,  for  the  management  of  post- 
mortem places  provided  by  the  authority;  and  under  the  same  Act  for  the 
removal  to,  and  detention  in,  hospital  of  infectious  patients  taken  off  ships 
and  vessels. 

In  London  the  County  Council  has  power  to  make  by-laws  for  a  great 
variety  of  purposes  relating  to  new  streets  and  roads,  plans  and  sites  of 
buildings,  drains  and  sewers,  etc.,  under  the  Metropolis  Local  Management 
Acts  and  London  Building  Act,  1894.  Under  the  Public  Health  (London) 
Act  both  the  County  Council  and  the  local  sanitary  authorities  are  requked 
to  make  by-laws  on  a  variety  of  subjects  which  will  be  alluded  to  in  their 
proper  place. 


670  HYGIENE    AND    PUBLIC    HEALTH 

Sewers. 
Public   Health  Act,   1875. 

Definition. — Sewer  includes  sewers  and  drains  of  every  description, 
except  drains  of,  and  used  for  tlie  drainage  of  one  building  only,  or  premises 
within  the  same  curtilage.  It  follows  from  this  definition  that  sewers 
may  be  on  private  land,  as  well  as  in  or  beneath  streets  or  highways 
which  are  dedicated  to  the  public.  The  meaning  of  the  word  "  curtilage  " 
is  obscure,  although  it  is  generally  held  to  signify  the  boundary  wall  of  the 
premises;  blocks  of  artisan  dwellings,  separated  froni  each  other  by  an 
open  causeway,  were  held  to  be  within  the  same  curtilage  (l^ilbrow  v. 
Vestry  of  Shoreditch). 

All  sewers,  with  the  exception  of  certain  private  sewers,  are  vested 
in  the  local  authority.  The  local  authority  must  keep  all  sewers  under 
their  control  in  repair,  and  must  make  such  sewers  as  may  be  necessary  for 
efEectually  draining  their  district.  They  must  cause  the  sewers  under 
their  control  to  be  so  constructed,  ventilated,  and  cleansed,  as  not  to  be  a 
nuisance  or  injurious  to  health  (sections  13,  15,  19). 

Where  complaint  is  made  to  the  Local  Government  Board,  that  a  local 
authority  has  made  default  in  providing  their  district  with  sufficient 
sewers,  or  in  the  maintenance  of  existing  sewers,  that  Board  can  compel 
the  local  authority  to  perform  its  duty  in  the  matter  of  such  complaint 
(section  299). 

The  owner  or  occupier  of  any  premises  within  the  district  of  a  local  autho- 
rity is  entitled  to  drain  his  house  into  a  sewer  after  due  notice,  and  on 
condition  of  complying  with  the  local  authority's  regulations  for  the  making 
of  communication  between  sewers  and  drains  (section  21). 

Section  26  prohibits  the  erection  of  any  building  over  a  sewer  of  an 
urban  authority  without  the  written  consent  of  such  authority.  This 
section  applies  to  combined  drains  which  are  sewers  on  private  land,  as 
well  as  to  sewers  in  public  roads  and  highways. 

Public  Health  Acts  Amendment  Act,   1890   [adoptive). 

In  places  where  this  Act  has  been  adopted,  where  two  or  more  houses 
belonging  to  different  owners  are  connected  with  a  public  sewer  by  a  single 
private  drain  (that  is  to  say,  a  drain  on  private  land  with  which  adjacent 
house  owners  are  not  at  liberty  to  make  drain  connections),  and  the  local 
authority  has  reason  to  believe  that  such  drain  is  defective  or  a  nuisance, 
the  local  authority  can,  under  the  powers  conferred  by  section  41  of  the 
Public  Health  Act,  1875,  after  twenty-four  hours'  notice  to  the  occupiers, 
proceed  to  open  the  ground  and  expose  the  drain,  and,  if  found  defective, 
execute  such  works  as  may  be  necessary  to  make  the  drain  secure  and 
sound,  and  recover  the  expenses  so  incurred  from  the  owners  of  the  houses. 
For  the  purposes  of  this  section,  therefore,  under  the  Amendment  Act  of 
i8go,  the  drain  of  more  than  one  building,  where  the  buildings  belong  to 
different  owners,  is  a  drain  for  which  such  owners  are  responsible;  but  if 
the  different  buildings  belong  to  one  owner,  such  drain  is  a  sewer,  for  which 
the  local  authority  is  responsible. 

Sections  16  and  17  of  the  same  Act  prohibit  the  introduction  into  any 
sewer  of  any  matter  which  would  interfere  with  the  flow  of  the  sewage,  or 
by  which  the  sewer  may  be  injured,  and  prohibits  the  introduction  of  any 
chemical  refuse  or  liquids  of  any  kind  having  a  temperature  exceeding 
110°  F.,  which  either  alone  or  in  combination  with  the  sewage  cause  a 
nuisance,  or  are  dangerous  or  injurious  to  health. 


SANITARY    LAW    AND    ADMINISTRATION  67I 

Metropolis  Local  Management  Acts,   1855  and  1862. 

In  London  the  definition  of  sewer  is  the  same  as  in  the  provinces  under 
tlie  PubHc  Health  Act,  1875,  witli  the  exception  that  the  combined  drain 
of  a  group  or  block  of  houses,  drained  by  a  combined  operation  under  the 
order  or  with  the  sanction  or  authorization  of  the  local  sanitary  authority 
(or,  prior  to  1855,  of  the  Metropolitan  Commissioners  of  Sewers),  is  a  drain 
for  whicli  the  owner  or  owners  of  the  houses  are  responsible,  and  not  a 
sewer  (1855  Act,  section  250;  1862  Act,  section  112).  Recent  decisions 
of  the  High  Court  of  Justice  and  of  the  Api)eal  Courts  have  shown  that  if 
the  scheme  of  drainage  sanctioned  by  the  authority  has  been  departed 
from  in  material  particulars,  or  if  the  drains  of  other  houses  have  been 
connected  surreptitiously,  or  without  authorization,  subsequent  to  the 
passing  of  the  plans,  the  combined  drain  is  a  sewer,  and  repairable  by  the 
local  authority.  In  fact,  no  combined  drains,  except  those  which  have 
been  sanctioned  by  authority,  and  which  at  date  practically  conform  with 
the  phins  passed  by  the  authority,  are  drains;  otherwise  they  are  sewers, 
repairable  by  the  ratepayers  at  large. 

The  control  of  the  main  sewers  in  London  and  of  the  disposal  of  the 
Metropolitan  sewage  is  vested  in  the  London  County  Council,  whilst  the 
street  and  other  branch  sewers  are  vested  in  the  Borough  Councils,  with 
whom  lies  the  regulation  of  the  method  of  making  communications  between 
all  house  drains  and  sewers.  As  in  the  provinces,  there  is  a  penalty 
imposed  for  building  over  any  sewer  or  interfering  with  any  sewer  without 
the  consent  of  the  local  authority;  and  there  is  a  prohibition  from  dis- 
charging into  any  sewer  any  matters  which  would  interfere  with  the  flow 
of  the  sewage,  or  any  liquids  which  would  damage  the  sewer  or  create  a 
nuisance. 

Disposal  of  Sewage. 

Section  17  of  the  Public  Health  Act,  1875,  expressly  states  that  nothing 
in  the  Act  shall  authorize  the  discharge  of  sewage  into  any  natural  stream 
or  water  course  until  the  sewage  has  been  freed  from  all  excrementitious 
or  other  foul  or  noxious  matter.  Sections  27  to  34  of  the  same  Act  give 
powers  to  local  authorities  to  construct  works  for  the  disposal  of  sewage, 
either  within  or  without  their  districts.  For  this  and  other  purposes  local 
authorities  can  borrow  money  on  the  credit  of  the  rates,  subject  to  the 
sanction  of  the  Local  Government  Board  (section  233).  The  regulations 
applicable  to  the  exercise  of  borrowing  powers,  which  must  be  complied 
with,  are  set  out  in  section  234  of  the  Act. 

Rivers  Pollution  Prevention  Act,  1876. 
By  section  7  of  this  Act  sanitary  authorities  must  give  facilities  to  manu- 
facturers to  carry  their  waste  waters  into  the  district  sewers,  provided 
such  waste  waters  do  not  afEect  prejudicially  the  sewers,  or  the  disposal 
of  the  sewage  on  land  or  otherwise  at  the  outfall,  or  are  not  themselves 
injurious  from  a  sanitary  point  of  view  or  by  reason  of  high  temperature. 
There  is  no  obligation  on  sanitary  authorities  to  construct  new  sewers 
to  receive  manufacturing  waste,  if  their  existing  sewers  are  only  just 
sufficient  for  the  ordinary  requirements  of  the  district,  and  are  unable  to 
receive  larger  volumes  of  manufactory  refuse. 

House  Drains. 

Public  Health  Act,   1875. 
By  section  23,  a  local  authority  can  require  the  owner  or  occupier  of 
any  house  which  is  within  their  district,  and  which  is  "  without  a  drain 
sufficient  for  effectual  drainage,"  to  make  a  drain  to  empty  into  any  sewer 


672  HYGIENE   AND    PUBLIC   HEALTH 

which  the  local  authority  is  entitled  to  use  (for  this  purpose),  which  is  not 
more  than  100  feet  from  the  site  of  such  house — i.e.,  from  the  boundary 
of  the  land  on  which  such  house  is  situate.  If  no  such  sewer  is  situate 
within  100  feet  of  the  boundary,  then  the  drain  may  be  made  to  empty 
into  a  covered  cesspool  or  other  receptacle,  not  being  under  any  house, 
as  the  local  authority  may  direct.  Such  drain  or  drains  must  be  of  such 
material  and  size,  and  laid  at  such  levels  and  with  such  fall,  as  the  surveyor 
to  the  local  authority  may  direct. 

By  section  25,  urban  authorities  can  insist  on  newly  erected  houses,  or 
houses  which  have  been  rebuilt  after  being  pulled  down  to  the  ground  floor, 
being  drained  in  a  similar  manner  to  the  above.  No  newly  erected  or 
rebuilt  house  may  be  occupied  until  a  proper  drain  has  been  provided. 

The  examination  or  testing  of  drains  (not  involving  the  opening  of  the 
ground)  is  provided  for  by  section  102  of  the  Act,  which  directs  that  any 
officer  of  a  local  authority  shall  be  admitted  into  any  premises  between 
the  hours  of  9  a.m.  and  6  p.m.  for  the  purpose  of  examining  as  to  the  exist- 
ence of  any  nuisance  thereon.  If  it  is  necessary  to  open  the  ground  to 
examine  the  state  of  the  drain,  a  written  application  must  be  made  by  some 
person  to  the  local  authority,  stating  that  the  drain  of  the  premises  in 
question  is  a  nuisance  or  injurious  to  health  (section  41).  The  local 
authority  must  then  in  writing  empower  their  officer,  after  twenty-four 
hours'  written  notice  to  the  occupier  of  the  premises,  or  in  case  of  emer- 
gency without  notice,  to  enter  such  premises  and  open  the  ground.  In 
the  event  of  the  drain  being  defective,  notice  is  to  be  served  upon  the  owner 
or  occupier  to  carry  out  the  necessary  works;  or  the  local  authority  may 
itself  execute  the  works,  and  recover  the  costs  so  incurred  from  the  party 
or  parties  who  are  liable  (section  41). 

•  By  the  Public  Health  Acts  Amendment  Act,  1907  (adoptive),  the  local 
authority  is  empowered  to  enter  premises  and  open  the  ground  on  the 
report  in  writing  of  their  surveyor  or  inspector  of  nuisances  that  there  is 
reason  to  suspect  that  any  drain,  water-closet,  earth-closet,  privy,  ashpit, 
or  cesspool  is  a  nuisance  or  injurious  to  health  (section  34).  By  section  38 
of  the  same  Act,  before  any  existing  drain,  which  does  not  communicate 
with  any  sewer  of  the  local  authority,  can  be  connected  to  the  sewer,  the 
local  authority  may  require  the  same  to  be  laid  open  for  examination  by 
the  surveyor,  no  connection  being  allowed  unless  certified  by  the  surveyor 
as  satisfactory.  The  Act  also  prohibits  the  use  of  a  rain-water  pipe  from 
the  roof  as  a  soil-pipe  or  as  the  ventilator  of  the  soil-pipe.  By  section  45, 
the  testing  of  drains  with  smoke  or  coloured  water  (not  the  water  [hydraulic] 
test)  is  provided  for,  subject  to  the  consent  of  the  owner  or  occupier  of 
the  premises;  and  a  notice  to  remedy  any  defect  discovered  on  testing 
may  be  served  on  the  owner. 

Section  40  of  the  Public  Health  Act,  1875,  requires  every  local  authority 
to  provide  that  all  drains  within  their  district  are  constructed  and  kept  so 
as  not  to  be  a  nuisance  or  injurious  to  health. 

By  section  157  of  the  Act,  urban  authorities  may  make  by-laws  with 
'respect  to  the  drainage  of  buildings,  but  such  by-laws  cannot  be  made  to 
apply  to  any  building  erected  in  any  place  which,  on  August  11,  1875, 
was  included  in  an  urban  sanitary  district  before  the  Local  Government 
Acts  came  into  force  in  such  place,  or  any  building  erected  in  any  place 
which,  on  that  date,  was  not  included  in  any  urban  district  before  such 
place  became  included  in  an  urban  district,  by  virtue  of  any  order  of  the 
Local  Government  Board.  In  places  where  the  Public  Health  (Amend- 
ment) Act,  1890,  Part  III.,  has  been  ado]:)ted,  section  23  extends  the  opera- 
tion of  drainage  by-laws  to  buildings  erected  before  the  time  above 
mentioned,  and  also  enables  rural  authorities  to  make  such  by-laws. 

It  must  be  clearly  understood  that  drainage  by-laws — that  is  to  saj', 


SANITARY  LAW  AND   ADMINISTRATION  673 

by-laws  specifying  the  materials  from  whicii  drains  are  to  be  constructed, 
their  jointing,  gradients,  ventilation,  disconnection,  methods  of  connecting 
branches,  etc. — cannot  be  made  to  apply  to  existing  drains  or  to  drains  of 
existing  buildings.  They  are  applicable  to  drains  about  to  be  laid  for  new 
or  old  buildings — -i.e.,  to  new  drains  of  new  buildings  or  to  new  drains  of 
old  buildings,  which  for  one  reason  or  another  are  about  to  be  redrained. 
Existing  drains  cannot  be  condemned  and  new  drains  required  because 
they — the  existing  drains — do  not  comply  in  whole  or  in  part  with  the 
regulations  contained  in  drainage  by-laws.  Where  existing  drains  are 
found  to  be  so  defective  that  they  cannot  be  repaired  so  as  to  render  them 
sound,  and  obviate  present  and  future  nuisance,  notice  can  be  served  for 
them  to  be  relaid.  In  such  a  case  it  is  probable  that  a  local  authority  can 
insist  on  the  new  drain  complying  with  their  drainage  by-laws. 

Metropdis  Local  Management  Acts  and  Public  Health  [London)  Act.  1891. 

Practically  the  same  provisions  exist  in  London  for  dealing  with  house 
drainage  as  in  the  provinces. 

The  Metropolis  ^fanagement  Act,  1855  (section  202),  gave  powers  to 
the  Metropolitan  Board  of  Works  to  make  drainage  by-laws,  and  such 
by-laws  have  been  prepared  by  the  London  County  Council. 
.  Section  15  of  the  Public  Health  (London)  Act  imposes  a  £'•,  penalty 
on  any  person  who  wilfully  destroys,  or  damages,  or  stops  up,  or  interferes 
with,  any  drain,  so  as  to  cause  it  to  be  a  nuisance  or  injurious  or  dangerous 
to  health — a  section  very  useful  in  restraining  the  acts  of  mischievous  or 
evil-disposed  persons. 

Section  42  of  the  same  Act  imposes  a  ;^2o  penalty  on  any  person  who  so 
repairs  or  constructs  a  drain  as  to  cause  it  to  be  a  nmsance,  or  injurious 
or  dangerous  to  health — again  a  most  useful  section  in  preventing  scamped 
or  defective  work. 

Water-closets,  Sanitary  Conveniences,  and  Sanitary  Fittings. 
Public  Health  Act,   i?>7S- 

Every  house  within  the  district  of  a  local  authority  must  have  a  siif&cient 
water-closet,  earth-closet,  or  privy,  and  an  ashpit,  furnished  with  proper 
doors  and  coverings;  and  no  house  may  be  erected  or  rebuilt  without 
similar  sanitary  accommodation  (sections  35  and  36). 

It  is  for  the  local  authority,  acting  on  the  advice  of  its  officers,  to  deter- 
mine in  each  case  what  constitutes  the  sufficiency  of  a  water-closet,  earth- 
closet,  or  privy.  Under  these  sections  a  proper  supply  of  water  to  flush  a 
water-closet  can  be  enforced.  As  regards  the  conversion  of  privies  into 
water-closets — a  pohcy  now  largely  taken  up  in  the  "  privy  "  towns  of 
the  Midland  and  Northern  counties — the  local  authority  has  no  power  to 
make  a  general  order  enforcing  the  replacement  of  privies  by  water-closets, 
but  has  power  in  any  particular  case  to  require  the  conversion,  if  satisfied 
that  the  privy  is  not  sufficient  for  the  health  requirements  of  the  people 
who  use  it  (Tinkler  v.  Wandsworth  Board  of  Works). 

Under  section  157,  urban  authorities  are  empowered  to  make  by-laws 
as  to  water-closets,  earth-closets,  privies,  ashpits,  and  cesspools,  in  the 
same  way  as  to  drains  (see  ante,  p.  672);  and  these  by-laws  are  extended 
in  the  same  way  by  the  Public  Health  Acts  Amendment  Act,  1890. 

Every  local  authority  must  provide  that  all  water-closets,  earth-closets, 
privies,  ashpits,  and  cesspools  are  constructed  and  kept  so  as  not  to  be  a 
nuisance  or  injurious  to  health;  whilst  the  provisions  of  section  41  apply 
equally  as  for  drains  where  it  is  desirable  to  open  the  ground — e.g.,  for  the 
examination  of  a  privy  or  cesspool  (see  ante,  p.  072). 

43 


674 


HYGIENE   AND   PUBLIC   HEALTH 


Public  Health  Acts  Amendment  Act,    1890. 


Section  2 1  imposes  a  105.  penalty  on  any  person  who  injures  or  improperly 
fouls  a  sanitary  convenience  which  is  used  in  common  by  the  occupiers 
of  two  or  more  separate  dwelling  houses,  or  by  other  persons;  and  a 
similar  penalty,  with  a  daily  5s.  penalty,  is  imposed  upon  all  persons  using 
a  common  closet  which  is  in  such  a  filthy  condition  as  to  be  a  nuisance  or 
annoyance,  from  want  of  proper  cleansing,  in  the  absence  of  proof  as  to 
who  is  the  person  actually  in  default. 

Public  Health  Acts  Amendment  Act,   1907. 

By  the  Public  Health  Acts  Amendment  Act,  1907  (adoptive),  the  local 
authority  may  require  a  new  building  to  be  provided  with  such  number 
of  proper  and  sufficient  water-closets  and  slop-closets  as  the  circumstances 
of  the  case  justify,  provided  there  is  a  sufficient  water-supply  for  flushing 
the  closets  and  a  sewer  available  for  receiving  the  w.c.  discharges.  Where 
there  is  a  "  sufficient  water-supply  and  sewer,"  the  local  authority  may  also 
require  proper  and  sufficient  water-closets  and  slop-closets  in  connection 
with  existing  buildings,  or  the  conversion  of  existing  closets  (not  being 
w.c.s  or  slop-closets)  into  water-closets  or  slop-closets.  Any  work  of 
alteration  done  by  the  local  authority  in  default  of  the  owner  in  respect  of 
a  pail-closet  is  to  be  paid  for  by  the  local  authority,  but  when  a  privy  is 
converted,  half  of  the  cost  is  to  be  borne  by  the  local  authority  and  the 
other  half  by  the  owner  (section  39). 

Section  49  gives  power  to  require  proper  sinks  and  drains  to  carry  away 
refuse  water  to  be  provided  in  all  buildings. 

By  the  same  Act  (section  43)  the  local  authority  may  require  the  removal 
of  any  urinal  or  sanitary  convenience  opening  on  any  street  which  is  a 
nuisance  or  offensive  to  public  decency.  If  a  public-house,  eating-house, 
or  place  of  public  entertainment  has  no  urinal  belonging  or  attached  to  it, 
the  local  authority  may  require  the  owner  to  provide  and  maintain  one. 
The  Act  authorizes  local  authorities  to  provide  and  maintain  public  con- 
veniences and  lavatories  in  or  under  any  public  street. 

Public  Health  {London)  Act,   1891. 

Very  much  the  same  provisions  apply  in  London  as  in  the  provinces. 
The  County  Council  has  made  by-laws  under  section  39  of  the  Act  which 
apply  to  all  new  fittings  in  new  or  in  existing  buildings  (water-closets,  soil 
pipes,  earth-closets,  ashpits,  cesspools,  dung  receptacles,  and  their  acces- 
sories). As  before  said  (see  p.  673),  existing  sanitary  fittings  must  not  be 
condemned  because  they  do  not  conform  to  the  by-laws,  but  all  new  fittings 
to  replace  existing  ones  must  comply  with  the  by-laws.  In  addition, 
every  person  who  intends  to  fix  a  new  water-closet,  earth-closet,  etc.,  is 
required  to  give  notice  of  such  intention  to  the  local  authority  (municipal 
borough).  Every  local  authority  (municipal  borough)  has  made  by-laws 
under  the  same  section  (39,  2)  with  respect  to  the  keeping  of  water-closets 
supplied  with  sufficient  water  for  their  effective  action.  Sections  1 5  and 
42  of  the  Act  (see  p.  673)  apply  equally  as  in  the  case  of  drains,  whilst 
section  46  incorporates  section  21  of  the  I'ublic  Health  Acts  Aniendment 
Act,  1890,  above  mentioned.  Any  person  who  thinks  himself  aggrieved 
by  any  notice  or  act  of  a  sanitary  authority  under  these  sections  may 
appeal  to  the  London  County  Council,  whose  decision  sliall  be  final. 


SANITARY   LAW    AND    ADMINISTRATION  675 


Nuisances. 
Public  Health  Act,   1875. 

The  nuisances  with  which  Public  Health  Acts  are  concerned  are  con- 
ditions which  are  either  actually  injurious  to  health  or  are  liable  to  be 
injurious  (i.e.,  dangerous)  to  health.  These  conditions  are  more  or  less 
delined  in  the  Acts  relating  to  public  health;  hence  these  nuisances  are 
also  called  "  statutory  nuisances."  These  Acts  provide  the  methods  and 
machinery  for  summarily  (i.e.,  expeditiously)  dealing  with  this  class  of 
nuisances,  but  this  does  not  exclude  the  invoking  by  any  person  aggrieved 
of  the  Common  Law  statutes  should  he  not  be  satisfied  with  the  remedies 
provided  by  the  special  Acts.  Nuisances  which  interfere  with  comfort 
or  with  the  enjoyment  of  life,  and  are  not  ejusdem  generis  with  those 
specifically  mentioned  in  the  Public  Health  Acts,  having  no  obvious  rela- 
tion with  dangers  to  health,  are  only  remediable  by  the  ordinary  operations 
of  the  Common  Law,  and  not  by  the  public  health  statutes. 

Nuisances  are  defined  in  section  91  of  the  Public  Health  Act,  1875: 

1.  "  Any  premises  in  such  a  state  as  to  be  a  nuisance  or  injurious  to 
health."  The  word  "  premises  "  includes  "  messuages,  buildings,  lands, 
easements,  and  hereditaments  of  any  tenure."  It  has  been  very  generally 
held  that  it  is  not  necessary  to  prove  actual  injury  to  health,  but  simply 
to  prove  that  the  nuisance  is  of  such  a  nature  as  to  be  capable  of  acting 
prejudicially  upon  health.  For  instance,  damp,  dirty,  and  dilapidated 
premises,  or  houses  invaded  by  bugs  or  other  vermin,  are  nuisances  under 
this  subsection,  because  they  are  all  capable  of  affecting  injuriously  the 
health  of  the  occupants. 

2.  "  Any  pool,  ditch,  gutter,  water  course,  privy,  urinal,  cesspool,  drain, 
or  ashpit  so  foul  or  in  such  a  state  as  to  be  a  nuisance  or  injurious  to  health." 
Under  this  subsection,  a  very  great  deal  of  the  sanitary  work  of  local 
authorities  is  carried  on.  The  enforcement  of  the  paving  of  yards  and 
areas  about  houses  is  usually  required  under  this  subsection,  to  obviate 
nuisance  from  standing  pools  of  dirty  water. 

3.  "  Any  animal  so  kept  as  to  be  a  nuisance  or  injurious  to  health." 

4.  "  Any  accumulation  or  deposit  which  is  a  nuisance  or  injurious  to 
health."  Trade  or  manufactory  deposits  are  exempt,  if  not  kept  longer 
than  necessary  for  the  purposes  of  tlie  business,  and  if  the  best  available 
means  have  been  taken  to  obviate  injury  to  health. 

5.  "  Any  house  or  part  of  a  house  so  overcrowded  as  to  be  dangerous 
or  injvurious  to  the  health  of  the  inmates,  whether  or  not  members  of  the 
same  family."  From  300  to  400  cubic  feet  per  head  is  usually  taken  as 
the  minimum  permissible,  with  half  these  amounts  for  children  under 
ten  years;  but  in  every  case  attention  should  be  paid  to  special  cir- 
cumstances— e.g.,  the  amount  of  ventilation  obtainable,  the  condition 
of  the  room,  the  class  of  people,  the  relationship  of  the  persons  over- 
crowded, etc. 

There  are  other  nuisances  relating  to  the  cleanliness,  ventilation,  and 
overcrowding  of  factories  and  workshops,  and  to  smoke,  which  will  be  dealt 
with  later  on. 

Section  92  requires  the  local  authority  to  cause  an  inspection  of  its 
district  to  be  made  from  time  to  time,  to  ascertain  what  nuisances  exist 
calling  for  abatement,  and  to  enforce  the  provisions  of  the  Act,  in  order  to 
abate  the  same  ;  and  section  102  (see  ante,  p.  672)  gives  powers  of  entry 
to  the  officers  of  the  local  authority  to  carry  out  the  provisions  of  the  Act. 
between  the  hours  of  9  a.m.  and  6  p.m.,  and  in  cases  of  nuisances  arising 
in  respect  of  any  business,  at  any  hour  when  such  business  is  in  progress. 


676  HYGIENE   AND   PUBLIC   HEALTH 

Public  Health  Acts  Amendment  Act,   1907. 

By  this  Act  (adoptive)  the  definition  of  nuisances  is  extended  to  (i)  any 
cistern  used  for  the  supply  of  water  for  domestic  purposes  so  placed,  con- 
structed, or  kept,  as  to  render  the  water  therein  liable  to  contamination, 
causing  or  likely  to  cause  risk  to  health ;  (2)  any  gutter,  drain,  shoot, 
stack-pipe,  or  down-spout  of  a  building  which  is  insufficient  or  defective 
and  causes  dampness  in  the  building ;  and  (3)  any  deposit  in  or  on  any 
building  or  land  which  causes  dampness  in  a  building  so  as  to  be  dangerous 
or  injurious  to  health. 

Public  Health  {London)  Act,   1891. 

The  provisions  relating  to  nuisances  in  London  are  the  same  as  in  the 
provinces.  In  order  to  prevent  the  possibility  of  nuisances  being  held 
to  be  only  conditions  which  have  actually  caused  injury  to  health,  the 
words  "  or  dangerous  "  have  been  introduced  into  this  Act,  so  that  the 
various  sections  read,  "  a  nuisance,  or  injurious  or  dangerous  to  health." 
In  London  also  (inhabited)  premises  without  water  fittings  are  a  nuisance, 
and  an  occupied  house  without  a  proper  and  sufficient  supply  of  water  is  a 
nuisance,  which  in  the  case  of  a  dwelling  house  renders  it  unfit  for  human 
habitation  (section  48). 

By  section  100  it  is  provided  that  the  County  Council,  when  satisfied 
that  a  local  sanitary  authority  has  made  default  in  doing  its  duty  under 
the  Act,  with  respect  to  the  removal  of  any  nuisance,  the  institution  of 
any  proceedings,  or  the  enforcement  of  any  by-law,  may  themselves  do 
what  is  necessary  to  carry  out  the  provisions  of  the  Act,  and  recover  the 
costs  from  the  defaulting  authority.  On  complaint  by  the  Countj'  Council 
to  the  Local  Government  Board  that  a  sanitary  authority  is  in  default 
in  executing  or  enforcing  the  provisions  of  the  Act,  the  Board  may,  after 
inquiry,  make  an  order  limiting  a  time  for  the  performance  of  the  duty 
by  the  sanitary  authority,  enforceable  by  mandamus;  or  the  Board  may 
appoint  the  County  Council  to  perform  the  duty,  and  in  that  event  the 
Council  is  invested  with  all  the  powers  of  the  sanitary  authority,  and  can 
recover  from  the  latter  all  expenses  incurred,  or  can  recoup  themselves 
by  levying  the  amount  by  a  rate. 

By  section  299  of  the  Public  Health  Act,  1875,  the  Local  Government 
Board  has  similar  powers  in  respect  of  urban  or  rural  authorities  who  have 
made  default  in  enforcing  any  of  the  provisions  of  the  Act  which  it  is  their 
duty  to  enforce.  The  Count}-  Council  may  make  the  complaint  to  the 
Board,  and  may  be  appointed  by  the  Board  to  execute  the  provisions  of  the 
Act  neglected  by  the  local  sanitary  authority  (Local  Government  Act,  1894). 

Procedure  to  abate  Nuisances,  and  to  carry  out  the  Provisions 

OF  the  Acts. 

Public  Health  Act,   1875. 

Sections  94  to  100  deal  with  the  procedure  necessary.  Information 
of  a  nuisance  may  be  given  by  any  aggrieved  person,  any  two  inhabitant 
householders,  any  officer  of  the  local  authority,  the  relieving  officer,  or 
police  officer.  A  complaint  having  been  made  to  a  local  authority  of  the 
existence  of  a  nuisance,  it  is  the  duty  of  the  sanitary  inspector  (inspector 
of  nuisances)  to  visit  the  premises  or  place,  and  to  report  to  the  next  meet- 
ing of  his  board  (local  authority).  The  latter,  if  satisfied  of  the  existence 
of  a  nuisance,  directs  that  a  notice  shall  be  served  (Form  A,  Schedule  IV.) 
on  the  person  by  whose  act,  default,  or  sufferance  the  nuisance  arises  or 
continues — or,  if  such  person  cannot  be  found,  on  the  owner  or  occupier 
of  the  premises  on  which  the  nuisance  arises — requiring  him  to  abate  the 


SANITARY   LAW   AND    ADMINISTRATION  677 

same  within  a  specified  time,  and  to  execute  the  works  necessary  for  that 
purpose.  Where  the  nuisance  arises  from  the  want  or  defective  construc- 
tion of  any  structural  convenience,  or  where  there  is  no  occupier  of  the 
premises,  the  notice  must  be  served  on  the  owner,  but  where  the  nuisance 
arises  from  the  neglect  or  default  of  the  occupier,  the  notice  must  be  served 
on  the  occupier.  Where  the  person  causinpj  the  nuisance  cannot  be  fovmd, 
and  it  is  clear  that  the  nuisance  does  not  arise  or  continue  by  the  act, 
default,  or  sufferance  of  the  owner  or  occupier  of  the  premises,  the  local 
authority  may  themselves  abate  the  same. 

"  Owner  "  under  this  Act  means  the  person  for  the  time  being  receiving 
the  rack-rent  of  the  lands  or  premises  in  question,  whether  on  his  own 
account  or  as  agent  or  trustee  for  any  other  person,  or  who  would  so  receive 
the  same  if  such  lands  or  premises  were  let  at  a  rack-rent;  the  latter  term 
meaning  rent  which  is  not  less  than  two-thirds  of  the  full  net  annual  value 
of  the  property  out  of  which  the  rent  arises. 

Notices  may  be  in  print  or  writing,  or  partly  in  either,  and  are  authenti- 
cated by  the  signature  of  the  clerk,  surveyor,  or  inspector  of  nuisances 
of  the  local  authority.  The  notice  may  be  served  by  delivering  it  or 
posting  it  by  registered  letter  to  the  residence  of  the  person  to  whom  it  is 
addressed.  The  notice  need  not  be  addressed  to  any  particular  individual, 
but  can  be  addressed  to  the  owner  or  occupier  of  the  premises,  as  the  case 
may  be,  and  either  left  upon  the  premises,  or,  in  the  case  of  the  premises 
being  empty  or  there  being  no  person  on  the  premises  to  receive  the  notice, 
it  may  be  fixed  to  some  conspicuous  part  of  the  premises  (sections 
266,  267). 

Should  the  notice  or  any  of  its  requisitions  not  be  complied  with  within 
the  time  specified,  it  is  the  duty  of  the  inspector  to  report  the  matter  to 
his  board  at  its  next  meeting,  who  should  instruct  him  to  make  a  complaint 
before  a  justice  (sworn  information  of  the  facts),  who  thereupon  is  to  issue 
a  summons  (Form  B,  Schedule  IV),  requiring  the  person  on  whom  the 
notice  was  served  to  appear  before  a  court  of  summary  jurisdiction.  The 
summons  must  be  applied  for  within  six  months  of  the  date  of  the  original 
offence;  otherwise  all  further  proceedings  are  invalidated. 

On  the  hearing  of  the  summons,  it  will  be  necessary  for  the  inspector 
to  give  evidence  as  to  the  existence  of  the  nuisance,  the  dates  of  his  visits 
to  the  premises,  and  the  service  of  the  notices  in  proper  form.  He  must  also 
be  prepared  to  prove  the  ownership  in  case  a  particular  person  is  sum- 
moned as  owner,  which  is  usually  done  by  the  production  of  the  rent  book 
or  the  evidence  of  a  tenant  of  the  house.  If  the  court  is  satisfied  as  to  the 
existence  of  a  nuisance,  it  may  make  (i)  an  abatement  order  (Form  C)— 
an  order  to  abate  the  nuisance  within  a  specified  time,  and  to  do  any  works 
necessary  for  that  purpose — or  (2)  a  prohibition  order  (Form  C),  prohibiting 
the  recurrence  of  the  nuisance,  with  necessary  works.  The  court  may  at 
the  same  time  inflict  a  penalty  not  exceeding  IS-  Where  the  nuisance 
proved  to  exist  is  such  as  to  render  a  house  unfit  for  human  habitation, 
the  court  may  make  (3)  a  closing  order,  prohibiting  the  use  of  the  house 
for  human  habitation  until  rendered  fit  for  that  purpose. 

If  the  person  on  whom  the  magistrates'  order  is  made  fails  to  comply 
with  its  requirements  within  the  time  specified  in  the  order,  he  can  be  again 
summoned;  and  if  he  fails  to  satisfy  the  court  that  he  has  used  all  due 
dihgence  to  carry  out  such  order,  he  may  be  fined  los.  per  day  during  his 
default  (abatement  order),  or  20s.  per  day  (prohibition  order).  If  the  local 
authority  prefers,  it  may  direct  its  officers  to  enter  the  premises  and  execute 
the  works  specified  in  the  order  of  the  court,  and  recover  in  a  summary 
manner  the  expenses  so  incurred  from  the  person  on  whom  the  order  is 
made  (County  Court  proceedings). 

A  person  convicted  under  these  sections  can  appeal  to  the  next  Court 


6/8  HYGIENE   AND    PUBLIC    HEALTH 

of  Quarter  Sessions,  within  fourteen  days  after  the  hearing,  provided  he 
gives  notice  of  such  intention  to  the  local  authority  and  enters  into  the 
necessary  recognizance. 

Public  Health  {London)  Act,   1891. 

The  procedure  in  London  is  practically  the  same  as  that  above  detailed, 
with  the  exception  that  by  section  3  of  the  London  Act  a  sanitary  inspector 
is  required  to  send  a  "  written  intimation  "  of  the  existence  of  a  nuisance 
as  soon  as  he  becomes  aware  of  it,  to  the  person  who  may  be  required  to 
abate  it.  The  written  intimation  should  be  merely  an  intimation  of  the 
existence  of  a  nuisance,  and  should  not  contain  any  threat  of  subsequent 
proceedings.  In  very  many  cases  these  written  intimations  lead  to  the 
abatement  of  the  nuisance,  without  recourse  having  to  be  made  to  the 
service  of  statutory  notices  authorized  by  resolutic  n  cf  the  Iccal  authority. 
Furthermore,  in  the  London  Act  "  any  person  "  may  give  information  of 
a  nuisance. 

Both  urban  local  authorities  in  the  provinces  and  the  iMetropolitan 
local  authorities  are  empowered  to  delegate  to  a  committee  their  powers 
as  to  the  reception  and  service  of  notices,  the  taking  of  legal  proceedings, 
and  generally  the  execution  of  the  sanitary  provisions  of  the  Acts. 

Smoke  Nuisances. 
Public  Health  Act,   1875. 

Section  91  defines  as  a  nuisance  any  fireplace  or  furnace  used  in  any 
trade  or  manufacturing  process  which  does  not  as  far  as  practicable  con- 
sume the  smoke  arising  from  the  combustible  used  therein.  There  is, 
however,  a  proviso  that,  in  the  event  of  a  person  being  summoned  for  this 
particular  form  of  nuisance,  the  court  must  hold  that  no  nuisance  had  been 
created,  and  must  dismiss  the  complaint,  if  it  is  satisfied  that  the  furnace 
is  constructed  in  such  a  manner  as  to  consume  as  far  as  practicable,  having 
regard  to  the  nature  of  the  manufacture  or  trade,  all  smoke  arising  there- 
from, and  that  such  furnace  has  been  carefully  attended  to  by  the  person  in 
charge. 

The  same  section  also  defines  as  a  nuisance  any  chimney  (not  being  the 
chimney  of  a  private  dwelling  house)  sending  forth  black  smoke  in  such 
quantity  as  to  be  a  nuisance. 

In  dealing  with  these  smoke  nuisances,  notices  are  required  to  be  served 
under  the  Act  in  the  same  manner  as  for  the  other  statutory  nuisances. 
If  evidence  is  forthcoming  that  the  smoke  issuing  was  black  and  in  such 
volume  as  to  be  a  nuisance  to  the  neighbourhood,  in  the  absence  of  rebutting 
evidence,  the  magistrates  are  bound  to  convict.  Should,  however,  the 
smoke  not  be  black,  but  any  lesser  shade  of  colour  (brown,  yellow,  etc.), 
evidence  must  be  adduced  by  the  prosecution  either  that  the  stoking  is  at 
fault,  that  coal  of  unsuitable  quality  is  being  used,  or  that  the  furnace  is  not 
constructed  so  as  to  consume  as  far  as  practicable  the  smoke  arising  from 
the  combustible  used  therein.  All  these,  naturally,  are  matters  much 
more  difficult  of  proof  than  where  the  only  evidence  necessary  is  the 
proof  of  black  smoke  and  nuisance,  and  are  also  much  more  liable  to  be 
upset  by  rebutting  evidence  called  on  behalf  of  the  defendant,  who  is 
entitled  to  show  that  the  furnace  is  constructed  in  such  manner  as  to  con- 
sume as  far  as  practicable,  having  regard  to  the  nature  of  the  manufacture 
or  trade,  all  smoke  arising  therefrom,  and  that  such  furnace  has  been 
carefully  attended  to  by  the  person  having  the  charge  thereof.  The  court 
must  hold  that  no  nuisance  is  created  within  the  meaning  of  the  Act,  and 
dismiss  the  complaint,  if  satisfied  that  such  is  the  case.  The  inspector 
should  always  make  time  observations,  showing  for  each  hour  the  numbers 


SANITARY    LAW    AND   ADMINISTRATION  679 

of  minutes  of  black  smoke,  of  coloured  smoke,  and  of  absence  of  visible 
smoke  respectively,  and  should  produce  this  evidence  in  court.  It  is 
usual  to  permit  black  smoke  to  issue  from  a  factory  chimney  for  a  few 
minutes  after  lig,hting  the  fires. 

Public  Health  [London)  Act,   1891. 
In  London  the  smoke  sections  {23  and  24)  of  the  Public  Health  (London) 
Act.   1 891,  contain  practically  identical  provisions,  the  authorities  being 
the  various  borough  councils. 

Scavenging  and  Cleansing. 

Public  Health  Act,    1875. 

Section  42  provides  that  every  local  authority  may,  and  when  required 
by  the  Local  Government  Board  shall,  themselves  undertake  or  contract 
for  (i)  the  removal  of  house  refuse  from  premises,  (2)  the  cleansing  of  earth- 
closets,  privies,  ashpits,  and  cesspools,  (3)  the  cleansing  and  watering  of 
the  streets.  If  the  local  authority  fails,  without  reasonable  excuse,  after 
written  notice  from  the  occupier  of  any  house,  to  remove  refuse  or  cleanse 
a  privy,  cesspool,  etc.,  within  seven  days,  the  defaulting  authority  is  liable 
to  pay  to  the  occupier  55.  per  day  during  such  default.  When  the  local 
authority  do  not  themselves  undertake  or  contract  for  the  removal  of 
house  refuse  and  cleansing  of  privies,  etc.,  they  may  make  by-laws  imposing 
those  duties  on  the  occupiers  of  premises,  together  with  the  cleansing  of 
footways  adjoining  their  premises. 

Urban  authorities  may  also  make  by-laws  for  the  prevention  of  nuisances 
arising  from  snow,  filth,  dust,  ashes,  and  rubbish,  and  for  the  prevention  of 
the  keeping  of  animals  on  premises  so  as  to  be  injurious  to  health.  In  urban 
districts  no  swine  may  be  kept  in  an}^  dwelling  house  so  as  to  be  a  nuisance. 
The  model  by-laws  of  the  Local  Government  Board  require  that  swine 
must  not  be  kept  within  .  .  .  feet  of  any  dwelling;  the  distance  should  be 
100  feet,  under  no  circumstances  should  it  be  less  than  60  feet.  An  urban 
authority  may  also  give  notice  by  public  announcement  requiring  the 
periodical  removal  of  all  manure  or  other  refuse  from  mews  and  stables. 
Penalties  are  incurred  for  infringing  these  notices  made  by  public  announce- 
ment, without  any  further  notice  being  required  to  be  sent  to  the  person 
in  default. 

Public  Health  Acts  Amendment  Act,   1890. 

Under  this  Act  sanitary  authorities  have  power  to  cleanse  alleys  and 
courts,  which  are  not  highways,  and  to  charge  the  occupiers  of  the  houses 
abutting  on  the  courts  with  the  cost  of  doing  so. 

Public  Health  [London)  Act,   1891. 

In  London,  footways  as  well  as  streets  must  be  cleansed  by  the  local 
authorities.  If  they  fail  to  do  so,  they  are  liable  to  a  fine  of  ;^20.  The 
London  authorities  are  also  required  to  remove  all  house  refuse  from  prem- 
ises. They  are  liable  to  a  ;^2o  fine  if  they  neglect  to  do  so  for  longer 
than  forty-eight  hours  after  the  receipt  of  a  complaint.  Dustmen  are 
prohibited  from  asking  for  gratuities.  Local  authorities  may  be  required 
to  remove  trade  refuse  from  any  premises,  but  the  occupier  of  the  premises 
must  pay  a  "  reasonable  "  sum  for  the  removal.  Any  question  as  to  what 
constitutes  trade  refuse  is  to  be  settled  by  a  Petty  Sessional  Court  (magis- 
trate).    Periodical  removal  of  manure  is  required  as  under  the  1875  Act. 

The  collection  of  house  anel  street  refuse  is  deemed  an  offensive  trade  in 
London,^  and  the  County  Council  has  control  over  the  local  authorities- 


68o  HYGIENE   AND   PUBLIC    HEALTH 

in  this  matter  as  if  the  business  was  an  offensive  trade.  In  London  no 
swine  may  be  kept  on  any  premises  within  40  yards  of  any  street  or  pubUc 
place. 

Every  sanitary  authority  is  required  to  make  by-laws  (i)  for  the  pre- 
vention of  nuisances  from  snow,  ashes,  filth,  etc.,  in  any  street;  (2)  for 
prevention  of  nuisances  from  offensive  matter  running  out  of  trade  premises; 
(3)  for  the  keeping  of  animals  on  any  premises;  (4)  for  the  paving  of  yards 
and  open  spaces  in  connection  with  dwelling  houses.  Straw  and  tan  may 
be  laid  in  the  streets  to  prevent  noise  in  case  of  illness. 

The  County  Council  is  required  to  make  by-laws  for  prescribing  the 
times — (i)  for  removing  by  road  or  water  faecal,  offensive,  or  noxious 
matters  or  liquids,  and  the  construction  and  covering  of  the  vessels  used 
for  the  purpose;  (2)  as  to  the  removal  and  disposal  of  refuse,  and  the 
closing  up  of  privies  and  cesspools. 

These  by-laws  must  be  enforced  by  the  local  sanitary  authorities. 

Water  Supply. 

Public  Health  Act,   1875. 

Power  is  given  to  all  authorities,  both  urban  and  rural,  to  provide  their 
districts  with  a  supply  of  water  proper  and  sufficient  for  public  and  private 
purposes  (section  51).  By  section  62  a  local  authority  may,  on  the  report 
of  their  surveyor  that  any  house  within  their  district  is  without  a  proper 
supply  of  water,  give  written  notice  to  the  owner  of  the  house  requiring 
him  within  a  specified  time  to  obtain  such  supply,  provided  that  it  can  be 
furnished  at  a  cost  not  exceeding  the  water  rate  authorized  by  any  local 
Act  in  force  within  the  district,  or  in  the  absence  of  any  local  Act  at  a 
cost  not  exceeding  2d.  per  week. 

By  section  70,  on  a  representation  being  made  to  a  local  authority 
that  within  their  district  the  water  in  any  well,  tank,  or  cistern,  public  or 
private,  which  is  used,  or  likely  to  be  used,  by  man  for  drinking  or  domestic 
purposes,  or  for  manufacturing  drinks  for  the  use  of  man,  is  so  polluted  as 
to  be  injurious  to  health,  the  local  authority  may  apply  to  a  court  of  sum- 
mary jurisdiction  for  a  summons  against  the  owner  or  occupier  of  the 
premises  to  which  the  well,  tank,  or  cistern  belongs.  The  court  may  at 
the  hearing  of  the  summons  make  an  order  for  such  well,  tank,  or  cistern 
to  be  temporarily  or  permanently  closed,  or  for  the  water  to  be  used  for 
certain  purposes  only.  If  the  court  sees  fit,  it  may  cause  the  water  com- 
plained of  to  be  analyzed  at  the  cost  of  the  local  authority. 

Public  Health   (Water)  Act,   1878. 

Section  3  makes  it  the  duty  of  every  rural  sanitary  authority  to  see  that 
every  occupied  dwelling  house  within  their  district  has  within  a  reason- 
able distance  an  available  supply  of  wholesome  water  sufficient  for  the 
use  of  the  inmates  of  the  house.  When,  on  the  report  of  an  officer  of  the 
rural  authority,  it  appears  that  an  occupied  dwelling  house  has  not  such 
a  supply,  and  that  it  can  be  provided  at  a  cost  the  interest  of  which  at  the 
rate  of  5  per  cent,  would  not  exceed  2d.  or  3d.  per  week,  as  the  Local 
Government  Board  may  determine,  the  authority  may  serve  a  notice  on 
the  owner  to  provide  such  a  supply,  within  a  specified  time.  If  such  notice 
is  not  complied  with,  a  second  notice  may  be  served,  to  the  effect  that  after 
one  month  from  the  date  of  its  service  the  authority  will  themselves  pro- 
vide such  supply.  At  the  expiration  of  the  month,  if  the  supply  has  not 
been  provided,  the  authority  may  themselves  execute  the  necessary  works, 
and  recover  from  the  owner  the  expenses  so  incurred.  By  section  6  it  is 
enacted  that  no  newly  erected  or  rebuilt  house  in  a  rural  district  may  be 


SANITARY    LAW    AND    ADMINISTRATION  68 1 

occupied  unless  the  owner  has  obtained  a  certificate  from  the  sanitary 
authority  that  there  is  provided  within  a  reasonable  distance  of  the  house 
an  available  supply  of  wholesome  water  sufficient  for  the  use  of  the  house. 
Section  7  requires  every  rural  sanitary  authority  to  take  such  steps  from 
time  to  time  as  may  be  necessary  to  ascertain  the  condition  of  the  water 
supply  within  their  district;  and  section  11  authorizes  the  Local  Govern- 
ment Board  to  invest  by  order  any  urban  sanitary  authority  with  all  or 
any  of  the  powers  of  this  Act  conferred  upon  rural  authorities. 

London. 

In  London  the  water  is  supplied  by  the  Metropolitan  Water  Board 
taking  water  from  the  Thames,  New  River,  Lea,  and  deep  wells  in  the 
chalk.  Their  powers  and  duties  are  regulated  by  private  Acts  of  the  eight 
Water  Companies,  the  predecessors  in  title  of  the  Metropolitan  Water 
Board,  and  by  the  Metropolis  Water  Acts  of  1852  and  1871.  The  Local 
Government  Board  has  certain  powers  of  control;  for  instance,  it  may 
make  periodical  examinations  of  the  water,  approve  new  sources  of  supply, 
approve  the  regulations  made  by  the  companies  as  regards  pipes,  taps  and 
other  house  fittings  for  the  prevention  of  waste  or  contamination,  and  also 
hold  inquiries  into  complaints  made  by  consumers  as  to  the  quality  or 
quantity  of  the  water  supplied  for  domestic  use.  The  London  County 
Council  has  power  to  require  a  constant  supply  of  water  in  any  district 
in  place  of  an  intermittent  supply.  The  Board  serves  notices  on  the 
houses  in  the  district  to  alter  their  pipes  and  fittings  to  meet  the  require- 
ments prescribed  for  a  constant  service,  and  unless  the  Board  can  show 
that  more  than  20  per  cent,  of  the  houses  have  not  adopted  the  prescribed 
fittings,  the  supply  must  be  made  and  continued  constant.  The  County 
Council  has  power  to  supply  the  prescribed  fittings  on  default  of  the  owner 
or  occupier  of  premises  scheduled  for  a  constant  supply,  and  recover  the 
costs  so  incurred. 

By  section  48  of  the  Public  Health  (London)  Act,  1891,  a  newly  erected 
or  rebuilt  house  must  not  be  occupied  until  the  sanitary  authority  has 
certified  that  it  has  a  proper  and  sufficient  supply  of  water;  and  an 
occupied  house  without  a  proper  and  sufficient  supply  of  water  is  a  nuisance 
liable  to  be  dealt  with  summarily  under  the  Act,  and  if  it  is  a  dwelling-house, 
shall  be  deemed  unfit  for  human  habitation.  This  term  "  a  proper  and 
sufficient  supply  of  water  "  is  not  sufficiently  definite  to  include  the 
provision  of  a  water  supply  to  every  floor  of  a  house  let  out  in  separate 
tenements^  (Marylebone  Police  Court,  1905).  By  section  49  the  Water 
Board,  on  cutting  ofE  the  water  of  an  inhabited  dwelling  house,  is  required 
to  give  within  twenty-four  hours  written  notice  of  the  fact  to  the  sanitary 
authority  of  the  district  under  a  ;£io  penalty.  By  section  50  every 
sanitary  authority  is  required  to  make  by-laws  for  securing  the  cleanliness 
and  freedom  from  pollution  of  tanks,  cisterns,  and  other  receptacles 
used  for  storing  water  for  drinking  or  domestic  purposes,  or  for  manu- 
facturing drinks  for  the  use  of  man.  The  other  powers  are  similar  to  those 
in  the  Public  Health  Act,  1875,  with  the  exception  that  in  the  case  of 
wells,  tanks,  or  cisterns,  of  which  it  is  desired  to  obtain  the  closure  it  is 
only  necessary  to  prove  that  the  water  is  "  so  polluted,  or  likely  to  be  so 
polluted,  as  to  be  injurious  or  dangerous  to  health." 

By  the  Water  Companies  (Regulation  of  Powers)  Act,  1887,  the  Water 
Board  is  prohibited,  under  a  IC)  daily  penalty,  from  cutting  off  the  water 
supply  for  non-payment  of  water  rates  in  the  case  of  houses  for  which  the 


1  But  this  has  since  been  provided  for  under  the  London  County  Council's 
General  Powers  Act,  1907. 


682  HYGIENE    AND   PUBLIC   HEALTH 

rates  are  compounded,  and  the  water  rate  is  payable  by  the  landlord.  In 
London  the  rateable  value  of  such  houses  must  be  ^.zo  or  under,  and  in  the 
provinces  ;^io  or  under. 

Rivers  Pollution. 

By  the  Rivers  Pollution  Prevention  Act,  1876,  the  following  acts  which 
might  pollute  a  stream  or  interfere  with  its  due  flow  are  prohibited:  (i)  The 
discharge  into  any  stream  of  solid  refuse  of  any  manufactory  or  quarry, 
or  any  rubbish,  cinders,  waste  or  putrid  solid  body;  (2)  the  discharge 
of  solid  or  liquid  sewage  matter,  unless  the  best  practicable  and  available 
means  have  been  adopted  to  render  harmless  such  matters;  (3)  the  dis- 
charge of  any  poisonous,  noxious,  or  polluting  liquid  from  any  manu- 
factory, with  the  same  proviso;  (4)  the  discharge  of  any  solid  or  liquid 
matter  from  .jiny  mine,  with  the  same  proviso. 

A  sanitary  authority  can  enforce  the  Act  by  taking  legal  proceedings, 
but  only  with  consent  of  the  Local  Government  Board  in  the  case  of 
(3)  and  (4).  That  Board,  in  giving  or  withholding  consent,  must  have 
regard  to  the  industrial  interests  involved,  and  to  the  circumstances  and 
requirements  of  the  locality. 

If  a  sanitary  authority  declines  to  initiate  proceedings,  any  aggrieved 
person  may  apply  to  the  Local  Government  Board,  who  may  direct  the 
authority  to  proceed. 

In  this  Act  "  stream  "  includes  the  sea  to  such  extent,  and  tidal  waters 
to  such  point,  as  may,  after  local  inquiry,  and  on  sanitary  grounds,  be 
determined  by  the  Local  Government  Board,  by  order  published  in  the 
London  Gazette  ;  save,  as  aforesaid,  it  includes  rivers,  streams,  canals, 
lakes,  and  water  courses,  other  than  water  courses  mainly  used  as  sewers 
and  emptying  directly  into  the  sea.  "  Solid  matter  "  does  not  include 
particles  of  matter  in  suspension  in  water.  "  Polluting  "  does  not  include 
innocuous  discolouration. 

Owing  to  the  great  manufacturing  interests  involved,  and  the  safe- 
guards against  procedure  so  abundantly  introduced  into  the  Act,  it  has 
been  but  little  put  into  operation  to  prevent  pollution  of  streams  in  the 
manufacturing  counties. 

By  the  Rivers  Pollution  Prevention  Act,  1893,  where  any  sewage  matter 
falls  or  flows  or  is  carried  into  any  stream  after  passing  through  or  along  a 
channel  which  is  vested  in  a  sanitary  authority,  such  sanitary  authority 
shall,  for  the  purposes  of  sections  3  of  the  Rivers  Pollution  Prevention  Act, 
1876,  b3  deemed  to  knowingly  permit  the  sewage  matter  so  to  fall.  How 
or  be  carried. 

Cellar  Dwellings. 

Ptiblic  Health  Act,   1875. 

There  is  no  definition  of  cellar  or  underground  room  in  this  Act,  but  in 
the  Public  Health  (London)  Act,  1891,  an  underground  room  includes  any 
room  of  a  house  the  surface  of  the  floor  of  which  room  is  more  than  3  feet 
below  the  surface  of  the  footway  of  the  adjoining  street,  or  of  the  ground 
adjoining  or  nearest  to  the  room.  Under  the  1875  -"^ct  any  cellar  in  which 
anyone  passes  the  night  is  deemed  to  h^  occupied  as  a  dwelling  (section  74). 

The  Act  prohibits  the  occupation  of  cellar  dwellings  not  lawfully  occu- 
pied prior  to  the  passing  of  the  Act;  and  existing  cellar  dwellings  may 
only  hi  occupied  on  cartain  conditions.  No  cellar  may  be  occupied 
separately  as  a  dwelling  (i.e.,  it  may  be  occupied  by  a  family  in  conjunction 
with  other  rooms  on  any  other  floor  of  the  house,  but  not  when  used  solely 
by  one  tenant  or  family)  unless  the  following  requisitions  are  complied 
with:  (i)  Unless  the  cellar  is  7  feet  in  height  from  floor  to  ceiling  through- 
out, 3  feet  of  this  height  being  above  the  level  of  the  street  or  grcurd 


SANITARY    LAW    AND    ADMINISTRATION  683 

adjoining;  (2)  unless  there  is  an  open  area  outside  extending  along  the 
entire  frontage  of  the  cellar  at  least  2^  feet  wide  and  sunk  6  inches  below  the 
level  of  the  floor  of  the  cellar;  (3)  unless  eflectually  drained  by  a  drain 
which  is  nowhere  less  than  i  foot  below  the  level  of  the  floor  of  the  cellar; 
(4)  unless  there  is  appurtenant  to  the  cellar  the  use  of  a  proper  water- 
closet,  earth-closet,  or  privy,  and  ashpit;  (5)  unless  the  cellar  has  a  fireplace 
with  chimney  and  flue,  and  an  external  window  of  at  least  9  superficial 
feet  in  area  clear  of  the  sash  frame  and  made  to  open.  In  the  case  of 
a  back  cellar  occupied  along  with  a  front  cellar  as  part  of  the  same  letting, 
the  window  need  not  have  a  larger  area  than  4  superficial  feet.  Steps 
in  the  area  giving  access  to  the  cellar  are  permitted,  if  not  across  or  oppo- 
site to  the  window,  and  at  least  6  inches  away  from  the  external  wall. 
Similarly,  steps  are  permitted  to  give  access  to  the  building  above  if  not 
across  or  opposite  to  the  window  (section  72).  There  is  a  penalty  of  20s. 
for  every  day  a  cellar  is  permitted  to  be  occupied  which  does  not  comply 
with  the  above  provisions,  after  notice  from  the  sanitary  authority;  and 
in  the  case  of  two  convictions  within  three  months,  an  order  mav  be  made 
for  the  closing  of  the  cellar. 

Public  Health   (London)   Act,    1891. 

Under  the  London  Act  the  ceiling  of  the  cellar  need  be  only  i  foot  in 
height  above  the  level  of  the  ground  or  street  adjoining  when  the  open 
area  is  6  feet  or  more  in  width.  The  open  area  must  be  properly  paved 
and  drained,  and  must  be  not  less  than  4  feet  wide.  The  walls  of  the 
room  must  be  constructed  with  a  proper  damp  course  and  secured  against 
dampness  of  soil,  the  soil  immediately  bslow  the  room  being  efEectually 
drained.  Any  drain  passing  under  the  room  is  to  be  constructed  of  gas- 
tight  pipe,  and  the  room  is  to  be  secured  against  the  rising  of  any  effluvia 
or  exhalation,  and  to  be  effectually  ventilated.  The  window  of  the  room 
is  to  have  a  total  area  clear  of  sash  frames  equal  to  at  least  one-tenth  of 
the  floor  area  of  the  room,  and  is  to  be  so  constructed  that  one-half  at  least 
can  be  opened,  the  opening  extending  to  the  top  of  the  window.  In  other 
respects  the  provisions  are  similar  to  the  Act  of  1875.  Unless  the  sanitary 
authorities  in  London  have  specially  dispensed  with  or  modified  any  of 
the  above  requisites  which  involved,  at  the  time  of  the  Act  coming  into 
force,  structural  alterations  of  buildings  (which  they  had  power  to  do 
within  six  months  of  the  commencement  of  the  Act),  the  above  provisions 
now  apply  to  all  underground  rooms  in  London  separately  occupied  as 
dwellings.  The  modifications  or  dispensations  might  not  in  any  case  alter 
the  requirements  of  the  Metropolis  ^lanagement  Acts  which  were  in  force 
prior  to  1891. 

Two  or  more  underground  rooms  occupied  together,  and  not  in  con- 
junction with  other  rooms  above  the  basement,  are  deemed  to  be  separately 
occupied  as  dwellings,  and  it  is  for  the  defendant  to  show  that  the  under- 
ground room  or  rooms  are  not  separately  occupied.  Evidence  (such  as 
the  presence  of  a  bed)  giving  rise  to  a  probable  presumption  that  some 
person  passes  the  night  there,  is  evidence  until  the  contrary  is  proved. 

Common  Lodging  Houses. 

Public  Health  Act,    1S75. 

There  is  no  definition  of  common  lodging  house  in  this  Act,  but  it  is 
usually  held  to  mean  a  lodging  house  in  which  ])ersons  of  the  poorer  class 
are  received  for  short  periods  (usually  a  night),  and,  although  strangers 
to  one  another,  are  allowed  to  inhabit  a  common  sleeping  rocm.  As  to  the 
liability  of  charitable  shelters  to  be  registered  and  treated  as  common 


684  HYGIENE    AND   PUBLIC    HEALTH 

lodging  houses,  the  latest  legal  decision  is  to  the  eSect  that,  unless  main- 
tained for  profit,  such  shelters  are  exempt. 

Every  common  lodging  house  is  required  to  be  registered  with  the  local 
authority,  who  must  keep  a  register  for  the  purpose,  but  may  not  register 
any  such  house  until  it  has  been  inspected  and  approved  for  the  purpose 
by  one  of  its  officers.  A  notice,  with  the  words  "  Registered  Common 
Lodging  House,"  is  to  be  affixed  to  the  outside  of  the  house.  Every  local 
authority  must  make  by-laws  (i)  as  to  the  number  of  lodgers  that  may  be 
received,  and  as  to  the  separation  of  the  sexes;  (2)  for  promoting  cleanli- 
ness and  ventilation  in  such  houses ;  (3)  for  the  giving  of  notices  and  the 
taking  precautions  in  the  case  of  any  infectious  disease ;  and  (4)  generally 
for  the  well  ordering  of  the  houses. 

The  model  by-laws  of  the  Local  Government  Board  provide  inter  alia 
that  the  cubic  space  per  head  in  the  sleeping  rooms  is  not  to  be  less  than 
300  feet,  two  children  counting  as  one  adult;  that  no  person  above  ten  years 
of  age  must  sleep  in  a  room  occupied  by  persons  of  the  opposite  sex,  but 
rooms  may  be  set  apart  for  the  sole  use  of  married  couples  if  every  bed  is 
screened  off.  No  bed  must  be  occupied  by  more  than  one  male  over  ten 
years  of  age.  The  floors  are  to  be  swept  daily,  and  washed  once  a  week. 
Windows  are  to  be  opened  fully  for  an  hour  in  the  morning,  and  the  same 
in  the  afternoon.  Beds  must  be  stripped  of  clothes  and  exposed  to  the  air 
for  an  hour  each  day,  and  must  not  be  reoccupied  within  eight  hours  of 
being  vacated.  All  refuse  and  slops  must  be  removed  from  the  rooms  before 
10  a.m.,  and  all  utensils  cleansed  daily.  The  windows,  yards,  closets,  and 
ashpits  must  be  kept  clean  and  in  good  order;  and  a  sufficient  supply  of 
basins,  towels,  and  water  must  be  provided  for  the  use  of  the  lodgers.  In 
the  case  of  infectious  disease  occurring,  the  keeper  of  a  common  lodging 
house  must  carry  out  all  the  measures  and  adopt  all  the  precautions 
directed  by  the  medical  officer  of  health. 

The  Act  requires  all  walls  and  ceilings  to  be  limewashed  twice  a  year 
(April  and  October),  and  the  keeper  may  be  required  to  make  a  daily 
report  to  the  local  authority  as  to  the  persons  resorting  to  his  house.  He 
must  give  immediate  notice  of  any  illness  or  fever  amongst  his  lodgers  to 
the  medical  officer  of  health  and  to  the  poor-law  relieving  officer  of  the 
union  or  parish. 

In  London  the  common  lodging  houses  are  regulated  by  the  Common 
Lodging  Houses  Acts  of  1851  and  1853,  the  provisions  being  practically 
identical  with  those  above  given.  Until  recently  these  houses  were  under 
the  supervision  of  the  JNletropolitan  Police;  they  are  now,  however,  con- 
trolled by  the  London  County  Council. 

Public  Health  Acts  Amendment  Act,   1907   {adoptive). 

The  local  authority  may  refuse  to  register  any  person  as  a  common 
lodging  house  keeper,  unless  satisfied  of  his  character  and  fitness  for  the 
position.  The  registration  may  remain  in  force  for  a  year  only,  and  be 
renewable  each  year.  The  obligation  is  placed  upon  the  keeper  to  provide 
proper  control  of  his  house,  and  he  or  the  deputy  must  be  on  the  premises 
from  9  p.m.  to  6  a.m.  A  register  must  be  kept  of  the  deputies  of  a  common 
lodging  house,  and  the  registration  may  be  cancelled  if  the  deputy  is  not 
a  fit  person  for  the  purpose.  Every  common  lodging  house  must  be  pro- 
vided with  sufficient  and  suitable  sanitarj'^  conveniences,  with  proper 
separate  accommodation  for  the  two  sexes,  where  men  and  women  are 
received.     The  flushing  arrangements  must  be  satisfactory. 


SANITARY   LAW    AND    ADMINISTRATION  685 

Houses  let  in  Lodgings. 

Public  Health  Act,   1875   [Section  gu). 

Local  authorities  are  empowered  to  make  by-laws  for  houses  let  in  lodg- 
ings or  occupied  by  members  of  more  than  one  family.  The  by-laws  thus 
made  provide  (i)  for  fixing  the  number  of  persons  who  may  be  taken  in 
as  lodgers,  and  for  the  separation  of  the  sexes;  (2)  for  the  registration  of 
the  houses;  (3)  for  their  inspection;  (4)  for  enforcing  drainage  and  privy 
accommodation,  and  for  promoting  cleanliness  and  ventilation;  (5)  for 
the  cleansing  and  limewashing  of  the  premises,  and  for  the  paving  of  the 
courts  and  yards;  (6)  for  the  giving  of  notices  and  the  taking  of  precautions 
in  case  of  any  infectious  disease. 

Houses  in  which  the  rooms  are  let  at  or  above  a  certain  weekly  rental, 
to  be  determined  by  the  local  authority,  are  usually  exempted  from  the 
operations  of  these  by-laws. 

The  minimum  cubic  space  permitted  is  usually  400  or  450  cubic  feet  per 
head  in  the  case  of  a  room  used  both  as  a  dwelling  and  sleeping  room, 
and  300  or  350  cubic  feet  in  the  case  of  a  room  used  for  sleeping  purposes 
only.  The  other  regulations  that  can  be  made  are  very  similar  to  those 
enumerated  as  applicable  in  the  case  of  common  lodging  houses,  with 
the  exception  that  it  is  seldom  that  any  such  by-laws  attempt  to  enforce 
the  separation  of  the  sexes,  and  the  limewashing  need  only  be  carried  out 
once  a  year  (April). 

Public  Health   [London]  Act,   1891    [Section  94). 
In  London  every  sanitary  authority   (borough  council)  is  required  to 
make  and  enforce  similar  by-laws  for  houses  in  its  district  which  are  let 
in  lodgings  or  occupied  by  members  of  more  than  one  family. 

Offensive  Trades. 

The  offensive  trades  enumerated  in  the  Public  Health  Act,  1875  (section 
112),  are  those  of  a  blood  boiler,  bone  boiler,  fellmonger,  soap  boiler,  tallow 
melter,  and  tripe  boiler.  The  model  by-laws  of  the  Local  Government 
Board,  in  addition  to  the  above,  also  relate  to  the  trades  of  a  leather 
dresser,  tanner,  fat  melter  or  extractor,  glue  maker,  size  maker,  blood 
drier,  and  gut  scraper.  Section  112  prohibits  any  person  from  establishing 
anew  within  the  district  of  an  urban  sanitary  authority,  without  their 
consent  in  writing,  any  offensive  trade.  There  is  a  £$0  penalty,  and  a 
continuing  penalty  of  405.  a  day.  Urban  authorities  may  make  by-laws 
with  regard  to  these  trades.  In  regard  to  trades,  other  than  those  above 
specified,  which  are  alleged  to  be  offensive,  they  must  be  shown  to  be 
ejusdem  generis  with  those  mentioned  as  offensive  in  the  statute.^ 

On  the  certificate  of  their  medical  ofticer  of  health,  or  of  two  medical 
practitioners,  or  of  any  ten  inhabitants  of  the  district,  that  a  trade  process 
is  causing  effluvia  which  are  a  nuisance  or  injurious  to  health,  magisterial 
proceedings  must  be  taken  by  the  urban  sanitary  authority  against  the 
defaulters  for  the  recovery  of  penalties.  Similar  proceedings  may  be 
taken  in  respect  of  a  nuisance  arising  from  an  offensive  trade,  carried  on 
outside  the  district,  in  a  court  having  jurisdiction  in  the  place  where  the 
offensive  trade  is  situate.  The  by-laws  of  the  Local  Government  Board 
which  form  the  model  for  the  by  -  laws  that  may  be  made  by  urban 
authorities,  contain  provisions  for  securing — (i)  The  storage  of  offensive 
materials   in  air-tight  receptacles,   so  as  to  prevent  escape  of  effluvia; 

^  By  the  Public  Health  Acts  Amendment  Act,  1907,  any  trade  or  manu- 
facture may  be  notified  as  an  offensive  trade  by  the  sanitary  authority,  if 
confirmed  by  the  Local  Government  Board. 


686  HYGIENE    AND   PUBLIC    HEALTH 

(2)  the  passage  of  offensive  vapours  arising  during  processes  of  melting, 
boiling,  etc.,  from  the  pans,  either  through  the  furnace  or  through  con- 
densers and  thence  through  the  furnace,  so  as  to  deprive  them  of  all 
noxious  properties ;  (3)  the  maintenance  of  efficient  drainage  on  the 
premises,  and  the  cooling  of  hot  liquids  before  discharge  into  the  drains ; 
(4)  the  maintenance  of  the  floors  in  good  condition,  and  their  daily 
cleansing,  also  the  daily  removal  of  all  sweepings  and  refuse  in  covered 
receptacles;  (5)  the  maintenance  of  walls  in  good  order,  their  periodical 
scraping  to  remove  any  adherent  filth,  and  their  limewashing  twice  a 
year;  (6)  the  cleansing  of  all  utensils  and  vessels  when  not  in  use; 
(7)  facilities  for  inspection  by  the  sanitary  authority's  officers. 

Under  the  Public  Health  (London)  Act,  1891,  the  County  Council  is 
the  authority  for  regulating  offensive  trades,  making  by-laws,  and  taking 
proceedings.  The  business  of  a  soap  boiler  may  be  carried  on  provided 
that  no  animal  oils  or  fats,  other  than  olein,  are  used  in  the  manufacture. 
The  fine  for  establishing  anew  in  London  the  trade  of  blood  boiler,  bone 
boiler,  manure  manufacturer,  soap  boiler,  tallow  melter,  or  knacker,  is  ;£so, 
with  a  daily  continuing  penalty  of  £^0.  These  businesses  are  absolutely 
prohibited  from  being  started.  With  the  consent  of  the  London  County 
Council,  a  fellmonger's,  tripe  boiler's,  or  horse  slaughterer's  business  may 
be  newly  established. 

Unsound  Food. 

Public  Health  Act,    1875   [Sections  11 6- 11 9). 

Any  medical  officer  of  health  or  inspector  of  nuisances  may  at  all  reason- 
able times  inspect  any  animal,  carcass,  meat,  poultry,  game,  flesh,  fish, 
fruit,  vegetables,  corn,  bread,  flour,  or  milk  exposed  for  sale,  or  deposited 
in  any  place  for  the  purpose  of  sale,  or  of  preparation  for  sale,  and  intended 
for  the  food  of  man,  the  proof  that  the  same  was  not  exposed  or  deposited 
for  any  such  purpose,  or  was  not  intended  for  the  food  of  man,  resting 
with  the  party  charged.  If  such  animal,  etc.,  appears  to  be  diseased,  or 
unsound,  or  unwholesome,  or  unfit  for  the  food  of  man,  the  officer  may  seize 
it,  and  convey  it  to  a  magistrate,  who,  if  satisfied,  condemns  the  same, 
and  orders  it  to  be  destroyed.  The  person  from  whom  the  seizure  is  made 
may  then  be  proceeded  against  by  summons  to  a  court  of  summary  juris- 
diction, and  is  liable  to  a  fine  of  £20  for  every  piece  of  food  seized,  or  to 
imprisonment  for  three  months.  There  is  a  ;^5  penalty  for  obstructing 
or  impeding  the  sanitary  authority's  officer  in  the  execution  of  his  duty. 
In  the  event  of  permission  being  refused  to  enter  any  premises  for  the 
purpose  of  discovering  if  any  unsound  food  is  concealed  therein,  a  com- 
plaint on  oath  must  be  made  to  a  justice,  who  can  grant  a  search  warrant. 
There  is  a  penalty  of  ;£20  for  obstructing  an  officer  wdio  is  armed  with  a 
search  warrant.  The  Public  Health  Acts  Amendment  Act,  1890,  extends 
the  power  to  inspect  and  seize  to  all  articles  intended  for  the  food  of  man 
sold  or  exposed  for  sale;  it  also  provides  for  the  condemnation  of  any 
article  by  a  justice  without  previous  seizure. 

Similar  provisions  exist  in  London.  In  addition,  proceedings  may  be 
taken  against  the  vendor  of  unsound  food  to  a  private  individual,  if  it  can 
be  shown  that  at  the  time  of  purchase  the  food  was  in  such  a  condition  as 
to  be  liable  to  be  seized  and  condemned. 

Under  the  Towns  Improvement  Clauses  Act,  1847,  any  officer  of  the 
Sanitary  Authority  may  inspect  and  seize  food  in  a  slaughter-house. 

Public  Health  (Regulations  as  to  Food)  Act,   1907. 
By  the  Public  Health  (Regulations  as  to  Food)  Act,   1907,  the  Local 
Government    Board    is    empowered    to    make    Regulations    authorizing 
measures  to  be  taken  for  the  prevention  of  danger  arising  to  public  health 


S\NITARY   LAW   AND    ADMINISTRATION  687 

from  the  importation,  preparation,  storage,  and  distribution  of  articles 
of  food  or  drink  (other  than  drugs  or  water),  intended  for  sale  for  human 
consumption.  In  the  year  1908  the  Local  Government  Board  issued 
regulations  to  be  enforced  by  port  sanitary  authorities  and  any  municipal 
council  or  district  council  whose  borough  or  district  includes  or  abuts 
on  any  part  of  a  customs  port,  which  part  is  not  within  the  jurisdiction 
of  a  port  sanitary  authority. 

The  Regulations  as  to  unsound  food  require  that  the  medical  officer  of 
health  may  examine  any  food  either  before  or  after  it  has  been  landed  from 
a  ship  within  the  district.  If  any  unwholesome  food  is  discovered,  it 
may  be  seized  and  carried  away,  or  its  removal  may  be  forbidden  until 
the  material  has  been  examined  by  a  justice,  except  when  the  food  is 
surrendered  for  immediate  destruction.  If  a  justice  is  satisfied  that  food 
is  unwholesome,  and  that  there  is  no  proof  that  it  is  not  intended  for 
human  consumption,  he  may  condemn  the  food  to  be  destroyed ;  but 
where  he  is  satisfied  that  the  food  is  not  intended  for  liuman  consumption 
he  shall  dismiss  a  complaint,  after  preparing  a  statement  containing  a 
detailed  description  of  the  food,  which  will  enable  it  to  be  subsequently 
identified,  and  a  copy  of  this  statement  must  be  furnished  to  the  sanitary 
authority.  A  justice  may  grant  a  search  warrant  to  a  medical  officer  of 
health  in  cases  where  food  has  been  landed  and  access  to  premises  for  the 
purpose  of  inspection  has  been  refused.  A  detailed  record  of  all  the 
unsound  food  destroyed  must  be  kept  by  the  sanitary  authority.  The 
medical  officer  of  health  is  empowered  to  take  samples,  and,  where  neces- 
sary, he  is  allowed  forty-eight  hours  for  the  necessary  examination.  It  is 
an  ofEence  to  fail  to  answer  truly  all  questions  put  with  reference  to  foods. 
Authorities  may  be  combined  for  the  purposes  of  these  Regulations;  and 
disputes  may,  on  the  application  of  all  the  parties,  be  referred  to  the  Local 
Government  Board  for  determination. 

Very  similar  Regulations  were  also  issued  in  the  year  1908  relating  to 
foreign  meat.  In  these  regulations  the  foreign  meat  is  classified  in 
three  classes  and  "  Foreign  meat  unclassed."  Foreign  meat  of  Class  i 
includes  scrap  meat,  or  other  pieces  of  such  shape  or  in  such  condition  as  to 
afford  insufficient  means  of  identification  with  definite  parts  of  a  carcass, 
but  which  is  not  in  tlie  form  of  sausage  or  other  prepared  article  of  food ; 
it  also  includes  tripe,  tongues,  and  kidneys  to  which  a  chemical  antiseptic 
has  been  applied,  and  any  unsalted,  unsmoked,  or  uncured  part  of  a  carcass 
of  a  pig.  Foreign  meat  of  Class  2  includes  the  entire  carcass  of  a  pig 
which  has  not  been  prepared  as  bacon  or  ham,  and  is  without  the  head  in 
its  natural  state  of  attachment  to  the  carcass,  and  without  the  lymphatic 
glands  in  their  natural  position.  Foreign  meat  of  Class  3  includes  the 
severed  parts  of  the  carcass  of  a  pig,  which  have  not  been  prepared  as  bacon 
or  ham,  and  which  is  in  a  package  carrying  an  official  certificate.  An 
"  official  certificate  "  means  a  mark,  stamp,  or  label,  which  is  recognized 
by  the  Board  as  admissible  as  evidence  that  the  meat  has  been  certified  by 
a  competent  authority  in  the  place  of  origin  to  be  free  from  disease  at  the 
time  of  slaughter,  and  that  the  meat  has  been  prepared  and  packed  with 
proper  safeguards.  The  Regulations  require  that  when  the  officer  of 
Customs  finds  or  suspects  that  foreign  meat  of  either  Class  i  or  Class  2 
is  aboard  a  ship,  he  shall  require  that  it  shall  not  be  removed  from  the 
ship  until  examined  by  the  medical  officer  of  health;  or  if  it  has  been 
delivered  overside,  it  shall  not  be  removed  in  the  meantime.  The  officer 
of  Customs,  however,  may  exercise  his  discretion  with  reference  to  meat 
of  Class  2  or  foreign  meat  unclassed,  and  he  may  or  may  not  call  upon 
the  medical  officer  of  health  to  examine  it.  On  receiving  notice  from  the 
officer  of  Customs,  the  medical  officer  of  health  must  forthwith  proceed 
to  examine  the  meat;  he  may  either  certify  that  it  may  be  forwarded  to 


688  HYGIENE   AND   PUBLIC   HEALTH 

its  place  of  destination,  or  he  may  forbid  the  renaoval  of  the  meat  for 
any  purpose  other  than  exportation.  Every  written  notice  and  certifi- 
cate must  sufficiently  describe  the  meat  to  suffice  for  its  identification, 
and  the  medical  officer  of  health  must  furnish  a  copy  of  any  certillcate 
to  both  the  officer  of  Customs  and  to  the  importer.  The  medical  officer 
of  health  may  examine  meat  which  has  been  removed  from  shipboard 
while  it  is  within  his  district,  even  after  the  removal  has  been  sanctioned 
by  the  officer  of  Customs;  and  if  the  meat  is  found  unsound,  he  may  forbid 
its  further  removal  for  any  other  purpose  other  than  exportation.  Within 
twelve  hours  after  the  receipt  of  a  copy  of  a  notice  by  the  medical  officer 
of  health  the  sanitary  authority  shall  give  notice  to  the  importer  that, 
unless  within  twelve  hours  he  gives  a  written  undertaking  that  he  will 
export  the  meat  at  his  own  expense,  or  will  prove  that  the  meat  is  not 
intended  for  sale  for  human  consumption,  the  meat  will  be  destroyed  under 
the  supervision  of  the  medical  officer  of  health.  Detailed  records  of  the 
destruction  of  foreign  meat  must  be  kept  by  the  sanitary  authority;  the 
medical  officer  of  health  is  empowered  to  take  samples  of  foreign  meat ;  it 
is  an  ofEence  not  to  answer  truly  all  questions  put;  authorities  may  com- 
bine for  the  purpose  of  carrying  out  these  regulations;  and  difierences 
may,  on  the  application  of  all  the  parties  aftected,  be  referred  to  the  Local 
Government  Board  for  determination. 

Horseflesh. 

By  the  Sale  of  Horseflesh  Regulation  Act,  1889,  which  applies  to  the 
whole  United  Kingdom,  the  flesh  of  horses,  asses,  or  mules  must  not  be 
sold  or  kept  for  sale  for  human  food  except  in  a  shop  or  stall,  over  which  is 
an  announcement,  in  legible  characters  4  inches  long,  that  horseflesh  is  sold 
there ;  nor  may  horseflesh  be  sold  to  any  purchaser  asking  for  other  meat. 

Slaughter  Houses. 

By  section  4  of  the  Public  Health  Act,  1875,  ^  slaughter  house  includes 
knackers'  yards  and  any  building  or  place  used  for  slaughtering  cattle, 
horses,  or  other  animals  for  sale. 

By  section  169  of  the  same  Act,  an  urban  authority  may  provide  (public) 
slaughter  houses,  sometimes  called  municipal  abattoirs,  and  must  make 
by-laws  for  the  management  and  charges  for  the  use  of  them.  They  may 
also  license  existing  slaughter  houses,  and  without  their  licence  no  place 
may  be  used  for  the  purpose  which  was  not  so  used  prior  to  1875.  This 
licence  does  not  require  periodical  renewal  when  once  given.  With  regard 
to  slaughter  houses  in  use  prior  to  the  Act,  they  need  not  be  licensed,  but 
they  must  be  registered  with  the  local  authority.  The  owner  or  occupier 
of  a  licensed  or  registered  slaughter  house  is  required  to  affix  a  notice  to 
that  effect  on  some  conspicuous  part  of  the  premises. 

In  places  where  Part  III.  of  the  Public  Health  Acts  Amendment  Act, 
1890,  has  been  adopted,  licences  for  slaughter  houses  may  be  limited  to 
twelve  months,  and  may  be  revoked  if  the  occupier  has  been  convicted 
of  selling  unsound  meat  or  exposing  it  for  sale.  This  Act  does  not  apply, 
so  far  as  regards  licences  for  limited  periods,  to  slaughter  houses  already 
licensed  or  registered  before  the  adoption  of  the  Act. 

The  Local  Government  Board  has  suggested  the  following  rules  as  to 
site  and  structure,  which  should  be  complied  with  by  slaughter  houses 
seeking  a  licence:  (i)  The  premises  should  not  be  within  100  feet  of  any 
dwelling  house,  and  should  be  freely  exposed  to  the  air  on  two  sides  at 
least.  (2)  Lairs  for  cattle  should  not  be  within  100  feet  of  a  dwelling  house. 
(3)  The  slaughter  house  should  not  be  below  the  ground  level.      (4)  The 


SANITARY   LAW    AND   ADMINISTRATION  689 

approach  should  not  be  on  an  incline  of  more  than  one  in  four,  nor  pass 
through  any  dwelling  house  or  shop.  (5)  There  should  be  no  room  or  loft 
over  the  slaughter  house.  (6)  The  water  tank  must  be  of  adequate  size 
with  its  bottom  not  less  than  6  feet  above  the  floor  of  the  slaughter  house. 
(7)  There  should  be  thorough  ventilation  of  the  slaughter  house.  (8)  The 
floor  should  be  well  paved  with  asphalt  or  concrete,  laid  with  proper  slope 
and  channel  to  a  gully,  with  trap  and  grating,  the  bars  of  which  should 
not  be  more  than  f  inch  apart.  There  must  be  effectual  drainage.  (9)  The 
surface  of  the  walls  in  the  interior  should  be  covered  with  hard,  smooth, 
impervious  material  to  a  sufficient  height.  (10)  There  must  be  no  water- 
closet,  privy,  or  cesspool  within  the  slaughter  house.  (11)  There  must  be 
no  direct  communication  between  the  slaughter  house  and  any  stable, 
water-closet,  privy,  or  cesspool.  (12)  Every  lair  for  beasts  must  be 
properly  paved,  drained  and  ventilated.  No  habitable  room  is  to  be 
constructed  over  any  lair. 

The  Local  Government  Board  has  also  issued  model  by-laws  as  to — 
(i)  Applications  for  licences  for  existing  premises  or  for  erection  of  new 
premises.  (2)  Registration  of  premises.  (3)  Access  for  inspection  by 
sanitary  officers.     (4)   Water  to  be  supplied  to  every  animal  in  a  lair. 

(5)  Mode  of  slaughter:  cattle  to  be  secured  by  the  head  before  felling. 

(6)  Drainage,  water  supply,  and  ventilation.  (7)  Cleanliness  of  premises: 
walls  and  floor  to  be  kept  in  repair,  and  cleansed  within  three  hours  after 
slaughtering ;  walls  and  ceiling  to  be  limewashed  four  times  yearly.  (8)  No 
dogs  to  be  kept  in  a  slaughter  house;  and  no  other  animal  unless  intended 
for  slaughtering,  and  then  only  in  a  lair,  and  not  longer  than  necessary 
to  prepare  it  for  killing  by  fasting.  (9)  All  refuse,  blood,  manure,  and 
garbage  to  be  placed  in  suitable  vessels  of  non-absorbent  material  with 
close  fitting  covers,  immediately  after  slaughtering,  which  are  to  be  re- 
moved within  twenty-four  hours,  the  vessels  being  then  cleansed.  All 
skins,  fat,  and  ofial  to  be  removed  within  twenty-four  hours. 

Any  person  guilty  of  an  infringement  of  the  by-laws,  when  in  force  in 
a  district,  is  liable  to  have  his  licence  suspended  for  two  months,  on  con- 
viction before  justices,  or  revoked  in  the  case  of  a  second  offence. 

In  London  all  slaughter  houses  are  annually  licensed  by  the  London 
County  Council. 

Dairies,  Cowsheds,  and  Milkshops. 

Under  the  Contagious  Diseases  (Animals)  Acts,  1 878-1 886,  the  Local 
Government  Board  has  issued  the  Dairies,  Cowsheds,  and  IMilkshops  Orders 
of  1885,  1886,  and  1899.  The  main  provisions  of  these  orders  are  as 
follows:  (i)  Every  cowkeeper,  dairyman,  and  purveyor  of  milk  must  be 
registered  in  a  register  to  be  kept  by  the  sanitary  authority  of  the  district. 
Cowkeepers  and  dairymen  who  only  make  or  sell  butter  and  cheese,  and 
persons  who  sell  milk  from  their  own  cows  in  small  quantities  to  workmen 
or  neighbours,  need  not  be  registered.  (2)  No  new  dairy  or  cowshed  may 
be  occupied  until  provision  is  made  to  the  reasonable  satisfaction  of  the 
sanitary  authority  for  the  lighting,  ventilation,  air  space,  cleansing,  drain- 
age, and  water  supply  of  the  premises.  (3)  As  regards  existing  dairies  and 
cowsheds,  these  matters  must  be  attended  to  as  far  as  is  necessary  or  proper 
for  the  health  and  good  condition  of  the  cattle,  the  cleanliness  of  the  milk 
vessels,  and  for  the  protection  of  milk  against  infection.  (4)  No  cowkeeper 
or  dairyman  sufEering  from  a  dangerous  infectious  disorder,  or  having  been 
recently  in  contact  with  a  person  so  sufEering,  may  milk  cows,  handle  milk 
vessels,  or  assist  in  the  trade  so  far  as  regards  the  production,  distribution, 
or  storage  of  milk,  nor  may  he  allow  any  person  so  sufEering  to  do  so. 
(5)  After  a  month's  notice  from  the  local  authority,  no  water-closet,  privy, 
cesspool,  or  urinal  is  allowed  to  be  within,  or  communicate  directly  with, 

44 


6go 


HYGIENE   AND   PUBLIC   HEALTH 


or  ventilate  into  any  dairy,  milk  store  or  milkshop.  (6)  No  milk  store  or 
milkshop  is  to  be  used  as  a  sleeping  apartment,  or  for  any  other  purpose 
likely  to  cause  contamination  of  the  milk.  No  swine  may  be  kept  in 
cowsheds  or  milk  stores.  (7)  The  milk  of  a  cow  sugaring  from  cattle 
plague,  pleuro-pneumonia,  foot  and  mouth  disease,  or  tubercular  deposits 
in  the  udder  (when  so  certified  by  a  veterinary  surgeon),  shall  not  be  mixed 
with  other  milk,  shall  not  be  sold  or  used  as  human  food,  and  shall  not 
be  sold  or  used  for  food  of  animals,  unless  it  has  been  boiled  (see  also  London 
County  Council  General  Powers  Act,  1904). 

The  above  order  of  the  Local  Government  Board  also  confers  power 
upon  any  urban  or  rural  sanitary  authority  to  make  and  enforce  regulations 
for  the  inspection  of  cattle  in  dairies  and  cowsheds;  for  prescribing  and 
regulating  their  lighting,  ventilation,  cleansing,  drainage  and  water  supply; 
for  securing  the  cleanliness  of  milkshops,  milk  stores,  and  milk  vessels; 


Fig.  92. — A  Sanitary  Cowshed.     Double  Byre  with  Central 
Feeding  Passage. 


and  for  prescribing  precautions  to  be  taken  by  all  purveyors  of  milk  against 
infection  or  contamination. 

Each  cow  is  usually  required  to  have  a  space  of  8  feet  by  4  feet  in  a 
separate  stall,  and  two  cows  8  feet  by  7  feet  in  a  common  stall.  The 
minimum  air  space  is  usually  fixed  at  600  cubic  feet,  but  when  the  ventila- 
tion is  imperfect,  800  cubic  feet  are  required  per  head.  The  floors  must 
be  imperviously  paved  and  drained  to  gullies  situated  outside  of  the  shed ; 
the  lower  parts  of  walls  to  be  of  non-absorbent  material;  there  must  be 
no  communication  of  the  cowshed  with  a  water-closet  or  privy;  and 
12  gallons  of  water  must  be  provided  for  the  use  of  each  cow.  All  milk 
vessels  to  be  steamed  or  scalded  immediately  after  use. 

The  Model  Regulations  of  the  Local  Government  Board  issued  in  1899 
distinguish,  as  regards  overcrowding  in  cowsheds,  between  those  from 
which  the  cows  are  habitually  turned  out  during  a  portion  of  each  day  to 
graze  on  grass  land,  and  those  in  which  the  cows  are  not  turned  out.  As 
regards  the  latter,  the  Regulations  provide  for  Sou  feet  of  air  space  for  each 
cow,  no  space  to  be  reckoned  which  is  more  than  16  feet  above  the  floor. 


SANITARY    LAW    AND    ADMINISTRATION  69I 

For  the  former  class  of  cowshed  no  such  provision  is  made.  As  regards  the 
milking  of  the  cows,  it  is  provided  tliat  at  the  time  of  milking  the  udder 
and  teats  of  the  cow  must  be  thoroughly  clean,  and  the  hands  of  the  milker 
must  be  clean  and  free  from  all  infection  and  contamination. 

In  those  districts  which  have  adopted  the  Infectious  Disease  i'rtvention 
Act,  1890,  the  medical  officer  of  health,  if  of  opinion  that  the  consumption 
of  milk  from  any  dairy  situate  within  or  without  his  district  is  likely  to 
cause  infectious  disease  in  his  district,  may,  by  order  of  a  justice  of  the  peace 
of  the  district  in  which  the  dairy  is  situate,  inspect  such  dairy,  and,  if  accom- 
panied by  a  veterinary  inspector,  inspect  the  animals  therein.  If  satisfied 
that  the  milk  sent  out  from  the  dairy  is  likely  to  cause  infection,  the  medical 
officer  reports  to  his  authority,  who  may  give  notice  to  the  dairyman  to 
appear  before  them,  after  twenty-four  hours'  notice,  and  make  an  order  on 
him  not  to  supply  any  more  milk  within  the  district  for  a  prescribed  period. 

In  London  the  Public  Health  (London)  Act,  1891,  confers  similar  powers 
upon  the  medical  officer  of  health.  In  London  cowhouses  have  to  obtain 
an  annual  licence  from  the  County  Council,  and  all  purveyors  of  milk 
have  to  be  registered  with  the  Council.  All  cowsheds  and  dairies  are 
subject  to  the  Council's  by-laws,  and  notice  of  the  occurrence  of  any  case 
of  infectious  disease  on  the  premises  has  to  be  sent  to  the  Council. 

For  the  above  purposes  the  term  "  dairy  "  "  includes  any  farmhouse, 
cowshed,  milk-store,  milk-shop,  or  other  place  from  which  milk  is  supplied, 
or  in  which  milk  is  kept  for  purposes  of  sale." 

Infectious  Diseases. 

Infectious  Diseases   [Notification)   Act,    1889. 

Tills  Act,  which  was  formerly  permissive,  is  now  made  compulsory 
throughout  the  country. 

The  compulsor}'  notifiable  infectious  diseases  are:  Small-pox;  cholera; 
diphtheria;  membranous  croup;  erysipelas;  scarlet  fever  or  scarlatina; 
typhus;  typhoid  or  enteric,  relapsing,  continued,  and  puerperal  fevers. 
A  local  authority  may  by  resolution  make  an  order  extending  compulsory 
notification,  either  temporarily  or  permanently,  to  any  other  infectious 
disease  not  included  in  the  above  list,  but  the  resolution  must  be  confirmed 
by  the  Local  Government  Board.  In  191 2  the  Local  Government  Board, 
by  a  General  Order,  required  the  notification  of  cerebro-spinal  fever  and 
acute  poliomyelitis.  The  diseases  to  which  compulsory  notification  has 
been  more  commonly  extended  are  measles,  whooping-cough,  chicken- 
pox,  and  diarrhoea  when  cholera  is  threatened.  Under  the  Animals 
(Notification  of  Disease)  Order  of  19 10,  of  the  Board  of  Agriculture  and 
Fisheries,  cases  of  anthrax,  glanders,  and  farcy,  in  the  lower  animals, 
must  be  notified  to  the  district  medical  ofhcer  of  health  by  the  inspector 
of  any  local  authority. 

The  persons  required  to  notify  to  the  medical  officer  of  health  of  the 
district  are:  (a)  The  head  of  the  family  to  which  the  patient  belongs; 
and  in  his  default  the  nearest  relative  of  the  patient  present  in  the  building 
or  in  attendance  on  the  patient ;  and  in  default  of  such  relatives  every  per- 
son in  charge  of  or  in  attendance  on  the  patient;  and  in  default  of  any 
such  person  the  occupier  of  the  building,  shall,  as  soon  as  he  becomes 
aware  that  the  patient  is  suffering  from  an  infectious  disease  to  which  this 
Act  applies,  send  notice  thereof  to  the  medical  officer  of  health  of  the 
district. 

[b)  Every  medical  practitioner  attending  on  or  called  in  to  visit  the 
patient  shall  forthwith,  on  becoming  aware  that  the  patient  is  suffering 
from  an  infectious  disease  to  which  this  Act  applies,  send  to  the  medical 
officer  of  health  for  the  district  a  certificate  stating    the  name  of  the 


692  HYGIENE   AND   PUBLIC   HEALTH 

patient,  the  situation  of  the  building,  and  the  infectious  disease  from 
which  in  his  opinion  the  patient  is  suffering.  There  is  a  40s.  penalty  for 
failing  to  send  the  notice  or  certificate  as  required.  No  proceedings  can 
be  taken  after  a  lapse  of  six  months  from  the  date  of  commission  of  the 
offence. 

Although  dual  notification  (bj-  the  householder  and  by  the  medical 
practitioner)  is  here  provided  for,  notification  by  the  householder  is  rarely, 
if  ever,  insisted  on  by  sanitary  authorities.  The  notification  by  the  house- 
holder, or  relatives,  or  person  in  charge,  or  occupier,  is  a  safeguard  for 
those  cases  in  which  medical  assistance  is  not  sought,  but  the  practical 
difficulty  of  proving  that  any  lay  person  was  aware  of  the  nature  of  an 
infectious  disease  occurring  in  his  family  or  house  is  so  great  as  to  render 
the  application  of  this  section  to  concealed  cases  of  infectious  disease 
exceedingly  difficult.  Every  medical  man  called  in  to  see  a  case  of 
infectious  disease  is  bound  to  notify,  even  although  this  has  already  been 
done  by  another  practitioner.  In  practice,  however,  this  is  but  very 
seldom  insisted  on.  Crown  buildings  are  exempted  from  the  operation 
of  the  Act. 

Under  an  Order  (1910)  the  Local  Government  Board  requires  the  medical 
officer  of  health  to  forward  to  the  Board  on  each  Monday  of  every  week 
a  complete  return  of  the  notifications  of  infectious  disease  received  during 
the  preceding  week.  Similar  information  is  to  be  furnished  to  the  county 
medical  officer  of  health. 

Public  Health  Act,   1875. 

Provisions  against  Infection. — Where  any  suitable  hospital  is  provided 
within  or  near  the  district  of  a  local  authority,  any  person  who  is  suffering 
from  any  dangerous  infectious  disorder,  and  is  without  proper  lodging  or 
accommodation,  or  lodged  in  a  room  occupied  by  more  than  one  family, 
or  is  an  inmate  of  any  common  lodging  house,  or  is  on  board  any  ship  or 
vessel,  may,  on  a  certificate  signed  by  any  legally  qualified  naedical  prac- 
titioner, by  order  of  any  justice,  be  removed  to  such  hospital  at  the  cost 
of  the  local  authority.  This  order  may  be  addressed  to  a  constable  or  to 
an  officer  of  the  local  authority,  and  any  person  who  wilfully  disobeys  or 
obstructs  its  execution  is  liable  to  a  ;£io  penalty. 

A  suitable  hospital  would  be  an  isolation  or  infectious  disease  hospital 
provided  by  the  local  authority,  or  established  out  of  charitable  funds,  or 
the  isolation  wards  of  some  general  hospital  or  infirmary  adapted  for  the 
treatment  of  infectious  cases.  The  magistrate  must  be  informed  of  the 
consent  of  the  hospital  authorities  to  receive  the  case. 

There  is  no  definition  of  "  dangerous  infectious  disorder  "  in  this  Act, 
but  it  is  usually  held  to  denote  any  of  the  diseases  which  are  compulsorily 
notifiable  in  the  district.  With  regard  to  other  diseases,  it  lies  in  the 
discretion  of  the  magistrate  before  whom  a  case  is  brought,  to  determine 
whether  any  particular  infectious  complaint  is  of  a  "  dangerous  "  character 
to  prevent  the  spread  of  which  precautions  must  be  taken. 

The  words  "  without  proper  lodging  or  accommodation  "  are  vague,  but 
the  most  recent  legal  decision  is  that  they  have  reference  to  the  unfitness 
of  the  lodging  or  accommodation  for  the  reception  and  treatment  of  a 
case  of  infectious  illness,  and  to  the  possible  danger  to  others  from  in- 
adequate isolation  of  the  case.  The  earlier  decisions  in  effect  ruled  that 
the  words  had  no  such  reference,  and  were  only  intended  to  apply  to 
tramps  and  casuals  sleeping  out  of  doors  or  in  places  not  intended  for 
human  habitation. 

"  Legally  qualified  medical  practitioner "  means  a  person  registered 
under  the  Medical  Act,  1858. 

When  it  is  intended  to  apply  to  a  magistrate  for  an  order  for  compulsory 


SANITARY    LAW    AND    ADMINISTRATION  693 

removal,  notice  of  the  time  and  place  of  making  the  application  should 
be  given  to  the  patient  or  his  friends. 

The  oi'licers  entrusted  with  the  duty  of  carrying  out  the  removal  of  the 
patient  are  not  justified  in  employing  force,  either  to  enter  the  premises 
or  apartment  occupied  by  the  patient,  or  to  remove  him  if  a  strenuous 
resistance  is  offered.  In  such  cases  the  only  remedy  is  to  summon  the 
obstructing  party  with  a  view  to  the  recovery  of  the  ^10  penalty.  The 
magistrates'  order  for  removal  does  not  carry  with  it  the  power  to  detain 
the  patient  in  hospital  until  he  is  recovered  or  no  longer  infectious. 

Local  authorities  may  provide  ambulance  carriages  for  conveying  in- 
fectious cases  to  hospital,  and  disinfecting  stations,  and  need  not  make 
any  charge  for  the  use  of  the  ambulances  or  for  disinfecting  infected  goods. 
They  may  also  destroy  infected  articles  and  compensate  the  owners.  They 
are  also  empowered  to  undertake  the  disinfection  and  cleansing  of  infected 
rooms  or  houses,  free  of  charge  to  the  occupiers. 

Any  person  who,  while  suffering  from  any  dangerous  infectious  disorder, 
wilfully  exposes  himself  without  proper  precautions  against  spreading 
the  said  disorder  in  any  street,  public  place,  shop,  inn,  or  public  con- 
veyance, or  enters  any  public  conveyance  without  previously  notifpng  to 
the  driver  that  he  is  so  suffering;  and  any  person  being  in  charge  of  any 
person  so  suffering  who  wilfully  exposes  such  sufferer;  and  any  person 
who  gives,  lends,  sells,  transmits,  or  exposes,  without  previous  disinfection, 
any  bedding,  clothing,  rags,  or  other  things  which  have  been  exposed  to 
infection,  is  liable  to  a  penalty  not  exceeding  £<^. 

The  word  "wilfully"  is  equivalent  to  knowingly.  There  can  be  no 
offence  if  there  is  no  knowledge  of  the  infectiousness  of  person  or  thing. 
The  words  "  in  charge  "  are  indefinite,  but  they  clearly  apply  to  children, 
scholars  in  boarding  schools,  and  patients  in  public  institutions,  but  they 
do  not  necessarily  extend  to  domestic  servants. 

Every  owner  or  driver  of  a  public  conveyance  must  immediately  provide 
for  the  disinfection  of  such  conveyance  after  it  has  to  his  knowledge 
conveyed  any  person  suffering  from  a  dangerous  infectious  disorder. 

Penalties  are  also  provided  against  any  person  (including  innkeepers) 
who  knowingly  lets  for  hire  any  house  or  part  of  a  house  in  which  any 
person  has  been  suffering  from  any  dangerous  infectious  disorder,  without 
having  the  same  disinfected  to  the  satisfaction  of  a  medical  practitioner. 
Any  person,  also,  who  lets  a  house  or  part  of  a  house,  and  on  being  ques- 
tioned by  an  intending  tenant  makes  false  statements  as  to  the  non- 
existence of  infectious  disease  within  six  weeks  previously,  is  liable  to  a 
penalty  of  ;^2o  or  a  month's  imprisonment. 

Any  local  authority  may  establish  a  hospital  for  infectious  diseases  in 
its  own  district,  and  there  is  no  restriction  on  the  establishment  of  such 
a  hospital  in  a  neighbouring  district;  nor  is  it  necessary  to  obtain  the 
consent  of  the  sanitary  authority  of  the  district  in  which  it  is  proposed  to 
establish  a  hospital. 

Section  133  enables  any  local  authority,  with  the  sanction  of  the  Local 
Government  Board,  to  provide  a  temporary  supply  of  medicine  and 
medical  assistance  for  the  poorer  inhabitants  of  their  district.  This  section 
is  intended  to  apply  to  times  of  epidemics,  such  as  small-pox,  cholera, 
plague,  etc. 

Infectious  Disease  {Prevention)  Act,   1890. 

This  is  a  permissive  Act.  Any  urban  or  rural  sanitary  authority  may 
adopt  the  whole  Act  or  one  or  more  of  its  sections.  The  provisions  of  the 
Act,  if  adopted,  shall  apply  to  the  infectious  diseases  specifically  mentioned 
in  the  Infectious  Diseases  Notification  Act,  and  may  be  applied  to  any  other 
infectious  disease  in  the  same  manner  as  that  Act  may  be  applied  to  such 
disease.     That  is  to  say.  at  the  discretion  of  the  sanitary  authority  it 


694  HYGIENE    AND   PUBLIC   HEALTH 

may  be  made  obligatory  on  the  public  to  take  the  same  precautions  to 
prevent  the  spread  of  measles,  whooping-cough,  or  chicken-pox,  as  are 
necessary  in  the  case  of  small-pox  or  typhus. 

By  section  15  of  the  Act,  local  authorities  are  required  to  provide,  free 
of  charge,  temporary  shelter  or  house  accommodation  with  any  necessarj- 
attendants,  for  the  members  of  any  family  in  which  infectious  disease  has 
appeared,  who  have  been  compelled  to  leave  their  homes  to  enable  them 
to  be  disinfected. 

Section  5  provides  that  on  a  certificate  of  the  medical  officer  of  health, 
or  other  registered  practitioner,  the  sanitary  authority  can  give  a  written 
notice  to  the  owner  or  occupier  of  infected  premises  that  the  premises 
will  be  cleansed  and  disinfected  by  the  authority  at  the  cost  of  the  owner 
or  occupier,  unless  such  owner  or  occupier  within  twenty-fom:  hours  replies 
stating  that  he  will  do  the  work  himself  to  the  satisfaction  of  the  medical 
officer  of  health.  Where  the  owner  or  occupier  is  unable  to  effectually 
cleanse  or  disinfect  the  premises,  this  may  be  done  without  notice  by  the 
officers  of  the  local  authority,  at  the  cost  of  the  latter. 

Section  6  enables  local  authorities  to  compel  the  delivery  b}'  house- 
holders to  them  of  infected  goods  for  the  purposes  of  disinfection,  and 
provides  for  compensation  to  be  paid  by  local  authorities  in  the  event  of 
an 3^  damage  to  the  goods. 

Section  13  prohibits  any  person  from  knowingly  casting  into  any  dustbin 
or  ashpit  any  infectious  rubbish. 

Section  7  prohibits  under  a  ;^io  penalty  the  concealment  of  the  existence 
of  infectious  disease  by  any  lodger  or  tenant  of  a  room,  rooms,  or  house, 
who  is  giving  up  his  tenancy,  in  cases  where  infectious  disease  has  existed 
within  a  period  of  six  weeks  from  the  time  of  ceasing  occupation.  The 
concealment  is  of  two  kinds:  (a)  In  not  giving  notice  to  the  owner,  and 
leaving  the  house  or  rooms  without  having  them  disinfected  to  the  satis- 
faction of  a  naedical  practitioner;  (b)  in  knowingly  making  false  answers 
when  questioned  by  the  owner  of  the  house,  or  by  a  person  negotiating 
for  the  hire  of  the  house  or  rooms.  This  section  supplements  sections  12S 
and  129  of  the  Public  Health  Act,  1875,  which  (see  p.  693)  heavily  penalize 
owners  or  landlords  for  letting  infected  lodgings  or  making  false  statements 
when  questioned  as  to  the  existence  of  infectious  disease. 

Section  12  provides  for  the  detention  in  hospital,  on  the  order  of  a 
magistrate,  for  a  specified  time,  of  any  person  who  is  a  patient  in  an  in- 
fectious disease  hospital,  and  who  would  not  on  leaving  such  hospital  be 
provided  with  accommodation,  where  proper  precautions  could  be  taken 
to  prevent  the  spread  of  infection.  Under  the  Public  Health  Act,  1875, 
only  persons  removed  to  hospital  from  ships  can  be  detained  in  hospital, 
under  regulations  made  by  the  sanitary  authority. 

Public  Health  Acts  Amendment  Act,   1907   {adoptive). 

Any  person  who  knows  that  he  is  suffering  from  a  notifiable  infectious 
disease  is  prohibited  under  a  40s.  penalty  from  engaging  in  any  occupa- 
tion or  carrying  on  any  trade  unless  he  can  do  so  without  risk  of  spreading 
the  disease. 

If  the  medical  officer  of  health  certifies  that  an}'  person  in  the  district 
is  suffering  from  an  infectious  disease  suspected  to  be  attributable  to 
milk  supplied  within  the  district,  the  local  authority  may  require  the 
dairyman  supplying  the  milk  to  furnish  the  medical  officer  of  health 
within  a  reasonable  time  a  complete  list  of  all  the  farms,  dairies,  or  places 
from  which  his  supply  is  derived  or  has  been  derived  during  the  past  six 
weeks;  and  if  the  supply,  or  any  part  of  it,  is  obtained  through  any  other 
dairyman,  may  make  a  similar  requisition  upon  that  dairyman.  The  sum 
of  6d.  is  to  b2  paid  for  every  twenty-five  names  in  the  list.     The  dairyman 


SANITARY   LAW   AND    ADMINISTRATION  695 

is  also  required  to  notify  to  the  medical  officer  of  health  of  the  district 
which  he  supplies  with  milk  all  cases  of  notifiable  infectious  disease 
imongst  his  employes,  as  soon  as  he  has  reason  to  suspect  that  such 
infectious  disease  exists. 

No  person  may  knowingly  send  to  a  wash-house  or  laundry  any  bedding 
or  clothes  which  have  been  exposed  to  infection  from  a  notifiable  infectious 
disease,  unless  previously  disinfected,  or  sent  with  proper  precautions 
and  a  notice  to  the  effect  that  they  have  been  exposed  to  infection.  Local 
authorities  may  cleanse,  purify,  or  destroy  any  ftlthy  articles  in  a  house, 
and  compensate  the  owner. 

Children  who  are,  or  have  been,  suffering  from  a  notifiable  infectious 
disease  are  not  to  be  sent  to  school,  after  notice  from  the  medical  officer 
of  health,  and  the  same  applies  to  children  who  have  been  exposed  to 
infection  from  a  notifiable  infectious  disease.  The  medical  officer  of 
health  is  to  give  a  certificate  when  it  is  safe  for  the  child  to  return  to 
school.  The  principal  of  any  school  in  which  any  child  is  suffering  from 
a  notifiable  infectious  disease  shall,  if  required,  furnish  to  the  local 
authority  within  a  reasonable  time,  a  complete  list  of  names  and  addresses 
of  scholars  attending  the  school  or  any  specified  department  of  it.  A 
sum  of  6d.  is  to  be  paid  for  every  twenty-five  names  on  the  list.  The  Act 
also  contains  provisions  as  to  the  use  of  library  books  by  persons  who  are 
in  an  infective  condition,  and  their  being  handed  over  to  the  local  authority 
for  disinfection. 

A  local  authority  is  excused  from  recovering  the  cost  of  maintenance 
of  infectious  patients  in  hospital,  if  satisfied  that  the  debt  should  be  re- 
mitted. The  local  authority  may  provide  temporary  shelter  or  house 
accommodation  for  the  occupants  of  a  house,  where  infectious  disease  has 
appeared,  and  also  attendants  at  the  shelter.  If  the  occupants  decline 
to  leave  the  house,  a  justice's  order  may  be  obtained  for  their  compulsory 
removal  to  the  shelter. 

The  Act  also  contains  provisions  as  to  the  conveyance  of  infected 
persons  in  public  vehicles,  and  the  disinfection,  where  necessary,  of  such 
vehicles ;  the  cleansing  and  disinfection  of  premises  or  of  any  infected 
articles  therein  contained;  and  prohibits  the  holding  of  "wakes"  over 
the  bodies  of  persons  who  have  died  of  a  notifiable  infectious  disease. 

The  local  authority  may  provide  nurses  for  attendance  on  infectious 
persons,  who  cannot  be  removed  to  an  isolation  hospital,  because  too  ill 
to  be  removed,  or  from  want  of  accommodation  at  the  hospital. 

Public  Health  {London)  Act,   1891. 

The  infectious  diseases  sections  of  this  Act  incorporate  the  various 
sections  of  the  Acts  already  mentioned  as  dealing  with  this  subject.  The 
London  notification  certificate  differs  from  that  required  by  the  Infectious 
Disease  (Notification)  Act,  1889,  in  that  the  age  and  sex  of  the  patient 
must  be  inserted,  and  also  whether  the  case  notified  by  the  practitioner 
occurs  in  his  private  practice  or  in  his  practice  as  medical  officer  of  any 
public  body  or  institution.  The  fees  are  the  same  under  this  Act  as  under 
the  Notification  Act — -namely,  25.  6d.  for  a  private  case  notified,  and  is.  for 
a  public  case. 

Everv  municipal  borough  has  power  to  extend  compulsory  notification 
to  diseases  other  than  those  in  the  scheduled  list  (see  p.  691)  in  its  own 
district,  whilst  the  London  County  Council  has  similar  powers  for  the  whole 
county  of  London.  There  is  no  power  conferred  on  provincial  County 
Councils  to  extend  the  Act  to  other  diseases,  as  has  been  done  for  the 
London  County  Council. 

In  London  the  "  dangerous  infectious  diseases  "  to  which  the  provisions 
penalizing  concealment  and  negligence  refer,  are  those  scheduled  in  the 


696  HYGIENE    AND    PUBLIC    HEALTH 

compulsorily  notifiable  list.  In  consequence  of  this  in  London  it  is  not 
compulsory  to  take  any  precautions  with  regard  to  the  sufferers  from 
mumps,  whooping-cough,  or  other  non-notifiable  disease,  with  the  excep- 
tion of  measles,  which  is  now  specially  scheduled  as  a  "  dangerous  infectious 
disease."  As  in  the  Infectious  Diseases  (Prevention)  Act,  each  sanitary 
authority  has  a  discretionary  power  as  to  applying  the  penalizing  sections 
to  diseases  ordinarily  non-notifiable,  but  which  have  been  rendered  com- 
pulsorily notifiable  by  resolution.  The  provision  of  disinfecting  stations 
and  goods  removal  vans  by  sanitary  authorities  is  compulsory,  and  the 
disinfection  is  gratuitous,  no  costs  or  expenses  incurred  being  recoverable 
by  the  sanitary  authority.  By  section  70  no  case  of  dangerous  infectious 
disease  may  be  conveyed  in  a  cab,  tram,  omnibus,  or  other  public  con- 
veyance. The  use  of  all  public  conveyances  for  such  purposes  is  absolutely 
prohibited  in  London.  An  ambulance  carriage  must  be  obtained  from  the 
Metropolitan  Asylums  Board  whenever  it  is  desired  to  convey  a  person 
suffering  from  a  notifiable  infectious  disease  from  one  place  to  another, 
for  which  a  charge  of  55.  is  made. 

The  fever  hospitals  of  the  Metropolis  are  under  the  control  of  the  Metro- 
politan Asylums  Board,  and  so  is  the  removal  of  patients  in  ambulance 
carriages  to  or  from  the  hospitals.  The  cases  admitted  to  the  Board's 
hospitals  are  small-pox,  diphtheria,  scarlet  fever,  enteric  fever,  and  typhus. 
Recently,  cases  of  measles,  whooping-cough,  and  puerperal  fever  have 
been  admitted.  The  Board  is  unable  to  acquire  sites  for  the  erection 
of  hospitals  unless  with  the  consent  of  the  Local  Government  Board. 

Isolation  Hospitals  Act,   1893. 

This  is  an  Act  to  enable  County  Councils,  etc.,  to  promote  the  establish- 
ment of  fever  hospitals. 

The  Act  does  not  apply  to  London,  Scotland,  or  Ireland,  nor  to  any 
English  county  borough.  It  applies,  with  the  consent  of  the  Town  Council, 
to  boroughs  having  a  population  of  10,000  or  over,  and  without  such 
consent  to  boroughs  of  less  than  10,000  population,  if  the  Local  Govern- 
ment Board  by  order  direct  that  the  Act  shall  apply  to  such  borough. 

Applications  may  be  made  to  a  County  Council  for  the  establishment 
of  an  isolation  hospital  for  infectious  diseases  by  a  local  authority  within 
the  county,  or  by  twenty-five  or  more  ratepayers  in  any  contributory  place 
— a  contributory  place  having  the  same  meaning  as  in  section  229  of  the 
Public  Health  Act,  1875.  If  the  County  Council  is  satisfied  that  a  prima 
facie  case  is  made  out  for  a  local  inquiry  as  to  the  necessity  for  the  establish- 
ment of  an  isolation  hospital,  they  may  direct  such  inquiry  to  be  made. 
The  County  Council  may  also  direct  the  medical  officer  of  health  of  the 
county  to  make  an  inquiry  as  to  the  necessity  of  an  isolation  hospital 
being  established  in  any  particular  district  in  the  county;  and  in  the 
event  of  the  medical  officer  reporting  that  such  a  hospital  ought  to  be 
established  in  any  district,  they  may  take  the  same  proceedings  for  the 
establishment  of  such  hospital  as  if  a  petition  had  been  presented  for  the 
establishment  of  such  a  hospital  by  the  local  authority  of  the  district  in 
question. 

After  the  local  inquiry  the  County  Council  may  make  an  order  dismissing 
the  petition,  or  constituting  "  a  hospital  district  "  out  of  one  or  more  local 
areas ,  and  directing  an  isolation  hospital  to  be  established  for  such  district. 
A  local  area  under  the  Act  means  an  urban  or  rural  sanitary  district,  or  a 
contributory  place.  The  County  Council  then  forms  a  hospital  committee, 
which  is  given  powers  to  acquire  a  site,  and  to  erect,  manage  and  maintain 
an  isolation  hosoital.  Power  is  given  to  make  a  scale  of  charges  for  the 
patients  in  the  hospital,  and  no  patient  is  to  suffer  any  disqualification 
or  loss  of  franchise  by  reason  of  his  treatment. 


SANITARY   LAW    AND    ADMINISTRATION  697 

MoRTt'ARIES,    AND    DISPOSAL    OF    THE    DeAD. 

Public  Health  Act.   1875. 

Any  local  authority  may,  and  ij  required  by  the  I-ocal  Government 
Board  shall,  provide  a  mortuary. 

The  body  of  any  dead  person  may,  by  order  of  a  justice,  on  the  pro- 
duction of  a  medical  certificate,  be  removed  to  a  mortuary,  if  it  is  in  such 
a  state  as  to  endanger  the  health  of  the  inmates  of  the  house  in  which  it  is 
kept.  The  same  power  of  removal  appHes  to  the  body  of  a  person  dead 
of  an  infectious  disease,  if  kept  in  a  room  where  persons  live  or  sleep. 

Infections  Disease  {Prevention)  Act,   1890. 

No  infectious  corpse  is  to  be  retained  for  more  than  forty-eight  hours 
in  a  dwelling  place,  sleeping  place,  or  workroom  without  the  sanction  of  a 
medical  practitioner.  Section  9  gives  power  to  prevent  the  removal  of  an 
infectious  corpse  from  a  hospital  to  the  home  of  relations,  or  to  any  place 
except  a  mortuary.  Section  10  enables  a  justice  to  order  the  removal  of 
a  dead  body  to  a  mortuary,  and  its  immediate  burial,  if  considered  advis- 
able, on  the  application  of  the  medical  officer  of  health ;  and  section  1 1 
provides  for  the  case  of  removal  of  an  infectious  corpse  in  a  public  con- 
veyance, which  is  unprovided  for  in  the  Act  of  1875. 

London. 

The  London  Act  contains  almost  identical  provisions  to  the  abovci 
but  the  provisions  for  the  most  part  relate  to  the  bodies  of  persons  who 
have  died  not  of  "  any  infectious  disease,"  but  of  a  "  dangerous  infectious 
disease." 

Cemeteries  and  Burial  Grounds. 

Information  of  a  death  must  be  given  to  the  Registrar  of  Births  and 
Deaths  within  five  days ;  or,  when  a  notice  is  sent  along  with  a  medical 
certificate,  within  fourteen  days. 

By  the  Public  Health  (Interments)  Acts,  1879,  both  urban  and  rural 
authorities  may  provide  cemeteries  for  their  districts,  and  must  do  so  if 
required  by  the  Local  Government  Board  on  the  ground  of  inadequacy  of 
existing  burial  places,  or  of  these  being  a  danger  to  the  public  health. 

The  Act  forbids  the  construction  and  laj-ing  out  of  a  cemetery  within 
200  yards  of  any  dwelling  house,  unless  with  the  consent  of  the  owner  and 
the  occupier  of  such  house. 

An  existing  burial  ground  may  be  closed  by  the  Home  Secretary  by  Order 
in  Council  under  the  provisions  of  the  Burial  Act,  1853.  Interments 
within  the  walls  of  churches  built  after  1848  are  forbidden  by  the  Public 
Health  Act,  1875. 

The  Regulations  for  Burial  Grounds  issued  by  the  Home  Secretary  in 
1863  provide  inter  alia — (i)  For  the  fencing  and  under-draining  of  the  site, 
to  prevent  water  rising  into  any  grave;  (2)  grave  spaces  to  be  laid  out,  and 
a  corresponding  plan  kept,  such  spaces  to  be  9  feet  by  4  feet  for  adults,  and 
4j  feet  by  4  feet  for  children  under  twelve  years;  (3)  a  register  of  graves 
is  to  be  kept;  (4)  a  bodv  buried  in  a  walled  vault  is  to  be  cemented  in,  and 
never  afterwards  disturbed;  (5)  only  one  body  to  be  buried  in  a  grave  at 
one  time,  unless  members  of  the  same  family;  (6)  no  grave  to  be  reopened 
until  fourteen  years  have  elapsed  for  an  adult,  or  eight  years  for  a  child, 
unless  to  bury  another  member  of  the  same  family,  in  which  case  at  least 
1  foot  of  earth  is  to  be  left  undisturbed  over  the  previously  buried  coffin; 
(7)  no  adult  body  to  hz  buried  within  less  than  4  feet  of  the  level  of  the 
ground ;  a  child  under  twelve  may  be  buried  within  3  feet. 


698  HYGIENE    AND   PUBLIC    HEALTH 

By  section  141  of  the  Public  Health  Act,  1875,  local  authorities  may 
make  by-laws  for  the  management  of  cemeteries. 

The  Cremation  Act,  1902,  gives  powers  to  burial  authorities  to  provide 
and  maintain  crematoria.  The  site  and  plans  of  the  crematorium  must 
be  approved  by  the  Local  Government  Board,  and  the  crematorium  must 
be  certified  by  the  burial  authority  to  the  Secretary  of  State  to  be  complete 
and  properly  equipped,  and  built  in  accordance  with  the  plans.  No  crema- 
torium may  be  constructed  nearer  than  200  yards  to  any  dwelling  house, 
except  with  the  consent  of  the  owner  and  occupier  of  such  house ;  nor  may 
it  be  within  50  yards  of  any  public  highway,  nor  within  the  consecrated 
part  of  the  burial  ground  of  any  burial  authority.  The  Secretary  of  State 
makes  regulations  as  to  the  maintenance  and  inspection  of  crematoria, 
and  as  to  the  practical  working  of  the  cremations. 

The  Cleansing  of  Persons  Act,    1897. 

By  this  permissive  Act  any  local  authority  has  the  power  of  cleansing 
persons  and  their  clothing  from  vermin,  when  an  application  is  made  to 
them;  and  local  authorities  may  expend  any  reasonable  sum  on  buildings, 
appliances,  and  attendants  that  may  be  required  for  the  carrying  out  of 
the  Act. 

The  Rag  Flock  Regulations,   191 2. 

The  Rag  Flock  Act,  191 1,  prohibits  any  person  selling  or  having  in  his 
possession  for  sale  any  flock  manufactured  from  rags,  or  using  for  the 
purpose  of  making  upholstery,  cushions,  or  bedding,  any  flock  manufac- 
tured from  rags,  unless  the  flock  conforms  to  such  standard  of  cleanliness 
as  may  be  prescribed  by  Local  Government  Board  Regulations.  The 
penalty  for  a  first  ofience  is  ;^io,  and  for  a  second  or  subsequent  offence  ;^so. 

The  Regulations  provide  that  flock  shall  be  deemed  to  conform  to  the 
standard  of  cleanliness  required  by  the  Act,  when  the  amount  of  soluble 
chlorine,  in  the  form  of  chlorides,  removed  by  thorough  washing  with 
distilled  water  at  a  temperature  not  exceeding  25°  C,  from  not  less  than 
40  grammes  of  a  well-mixed  sample  of  flock,  does  not  exceed  30  parts  of 
chlorine  in  100,000  parts  of  the  flock. 

The  London  County  Council  (General  Powers)  Act,   1904. 

By  Part  IV.  (Sanitary)  of  this  Act,  on  the  certificate  of  the  medical  officer 
of  health  that  any  articles  in  any  house  or  part  thereof  are  in  such  a  filthy, 
dangerous,  or  unwholesome  condition  that  health  is  affected  or  endangered 
thereby,  or  that  the  cleansing  or  purifying,  or  destroying  of  any  such  article 
is  requisite  to  prevent  risk  of,  or  to  check  infectious  disease,  the  sanitary 
authority  may  cause  any  such  articles  to  be  at  their  own  expense  cleansed 
or  purified  or  destroyed,  compensation  being  given  to  the  owner  for  un- 
necessary damage  or  for  articles  destroyed. 

On  the  certificate  of  the  medical  officer  of  health  that  any  house  or  part 
thereof  is  infested  with  vermin,  the  sanitary  authority  must  give  notice 
to  the  owner  or  occupier  requiring  him  within  a  specified  time  to  cleanse 
such  house  or  portion  thereof,  and  if  so  required  in  the  notice  to  remove  the 
wall  papers,  and  to  take  such  other  steps  for  the  purpose  of  destroying 
and  removing  vermin  as  the  case  may  require.  A  fine  not  exceeding  los. 
a  day  may  be  inflicted  for  every  day  during  which  default  is  made  in  con- 
plying  with  the  requirements  of  the  notice;  and  after  the  expiration  of 
the  period  specified  in  the  notice  the  sanitary  authority  may  themselves 
do  the  work  and  recover  summarily  as  a  civil  debt  all  reasonable  costs 
and  expenses. 

Section  22  enables  any  sanitary  authority  to  require  the  removal  of  any 


SANITARY   LAW    AND    ADMINISTRATION  6q9 

sanitary  convenience  erected  in  or  accessible  from  any  street  which  is  a 
nuisance  or  ofiensive  to  public  decency,  and  to  require  the  reconstruction 
of  the  same  so  as  to  abate  the  nuisance  and  remove  the  offence  against 
public  decency.  Section  23  enables  sanitary  authorities  to  cause  fixed 
ashpits  to  be  removed  and  their  site  cleared,  wherever  movable  ashpits 
have  been  provided.  Section  24  gives  powers  for  the  entry  and  inspection 
of  premises  for  the  purposes  of  the  Act. 

By  Part  V.  (Tuberculosis  of  the  Udder  in  Cows) ,  if  a  veterinary  surgeon 
appointed  by  the  London  County  Council  for  the  purposes  of  the  Dairies, 
Cowsheds,  and  Milkshops  Order,  1899,  suspects  that  any  cow  in  any  dairy, 
farm  or  cowshed  situate  in  the  county  (exclusive  of  the  City)  is  suffering 
from  tuberculosis  of  the  udder,  he  may  cause  such  cow  to  be  removed  from 
the  farm  or  cowshed.  The  value  of  the  cow  must  then  be  agreed  between 
the  Council  and  the  owner,  and  the  Council  shall  cause  the  cow  to  be 
slaughtered  and  its  carcass  to  be  examined  by  a  qualified  veterinary  sur- 
geon. If  the  cow  is  found  to  have  suffered  from  tuberculosis  of  the  udder, 
three-fourths  the  value  as  agreed  must  be  paid  by  the  Council  to  the  owner, 
the  sum,  however,  not  to  exceed  £22  10s.,  and  one  half  the  costs  of  any 
independent  veterinary  surgeon  who  may  have  been  employed  as  valuer. 
If  the  cow  was  found  to  be  free  from  tuberculosis  of  the  udder,  the  whole 
value  of  the  cow  must  be  paid,  the  sum  not  to  exceed  £^0,  and  a  further 
sum  of  ;^i,  and  the  costs  of  any  independent  valuer. 

The  Prevention  of  Epidemic  Dise.\ses. 

Public  Health  Act,    1875. 

Section  130  enables  the  Local  Government  Board  to  make  regulations 
for  the  treatment  of  persons  infected  with  cholera  or  other  epidemic  disease, 
and  for  preventing  the  spread  of  these  diseases  on  land,  and  on  sea  up  to 
the  three  mile  coast  Umit.  By  section  134,  whenever  any  part  of  England 
appears  to  be  threatened  with  or  is  affected  by  any  formidable  epidemic, 
endemic,  or  infectious  disease,  the  Local  Government  Board  may  make 
regulations  for  (i)  the  speedy  interment  of  the  dead;  (2)  house  to  house 
visitation;  (3)  medical  aid  and  accommodation;  (4)  for  the  promotion  of 
cleansing,  ventilation,  and  disinfection,  and  for  preventing  the  spread  of 
disease.  The  local  authority  of  any  district  within  which  such  regulations 
are  declared  to  be  in  force  is  charged  with  the  execution  and  enforcement 
of  the  regulations.  By  the  Public  Health  Act  of  1889,  regulations  made 
by  the  Local  Government  Board  in  relation  to  cholera  or  choleraic  diarrhcea 
may  be  put  in  force  by  officers  of  Customs,  and  may  provide  for  the  deten- 
tion of  vessels  and  of  persons  on  board  vessels. 

The  same  provisions  are  in  force  in  London. 

The  Notific.\tion  of  Births  Act,   1907. 

The  Act  requires  that,  if  adopted,  the  local  authority  shall  bring  the 
provisions  of  the  Act  to  the  attention  of  all  medical  practitioners  and 
midwives  practising  in  their  area. 

These  provisions  may  be  briefly  summarized  as  follows: 
Primarily,  the  "  duty  "  of  notifying  a  birth  to  the  medical  officer  of 
health  devolves  upon  the  father  of  the  child,  if  he  be  resident  in  the  house 
at  the  time  of  its  occurrence;  secondarily,  upon  "  any  person  in  attendance 
upon  the  mother  at  the  time  of,  or  within  si.x  hours  after  the  birth." 
The  notice  must  be  "  given  by  posting  a  prepaid  letter  or  postcard  .  .  . 
within  thirty-six  hours  after  the  birth,"  or  by  delivery  of  a  "  written 
notice  of  the  birth  (in  either  case)  at  the  office  of  the  medical  officer  within 
the  same  time."     The  local  authority  are  required  to  "  supply  without 


700  HYGIENE    AND    PUBLIC    HEALTH 

charge  addressed  and  stamped  postcards,  containing  the  form  of  notice, 
to  any  medical  practitioner  or  midwife,  residing  or  practising  in  their  area, 
who  applies  for  the  same."  The  notification  is  "in  addition  to,  and  not 
in  substitution  for,  the  requirements  "  of  the  Act  "  relating  to  the  registra- 
tion of  births,"  and  it  applies  to  any  child  born  "  after  the  expiration  of 
the  twenty-eighth  week  of  pregnancy,  whether  alive  or  dead."  Liability 
to  a  penalty  not  exceeding  20s.  is  incurred  by  any  person  who  fails  to  give 
notice  of  a  birth.  The  Local  Government  Board  may,  by  Order,  put  this 
Act  in  force  in  any  district. 

The  Children  Act,   1908. 

Many  of  the  provisions  of  this  Act  are  designed  either  to  promote  the 
moral  and  physical  health  of  children  or  to  reduce  infantile  mortalit}'. 
The  Act  came  into  operation  on  April  i,  1909.  It  consolidates  and  amends 
the  law  relating  to  the  protection  of  children  and  young  persons,  reformatory 
and  industrial  schools,  and  juvenile  offenders;  and  otherwise  amends  the 
law  with  respect  to  children  and  young  persons. 

Part  I.  deals  with  infant  life  protection,  and  requires  that  anyone  under- 
taking, for  reward,  the  nursing  and  maintenance,  for  more  than  forty- 
eight  hours,  of  one  or  more  infants  under  the  age  of  seven  years  apart  from 
their  parents  shall  notify  the  local  authority  of  the  fact  within  forty-eight 
hours,  and  shall  repeat  the  notification  on  change  of  residence;  notification 
must  also  be  given  within  forty-eight  hours  of  the  death  of  any  such  infant, 
and  within  twenty-four  hours  a  notification  must  be  sent  to  the  coroner. 
Such  person  must  have  no  interest  in  any  life  assurance  policy  with  refer- 
ence to  a  child  in  their  charge.  Every  local  authority  must  prosecute 
inquiries  to  ascertain  whether  any  persons  liable  to  notification  are  residing 
in  the  district,  and  if  so,  shall  provide  infant  protection  visitors.  Local 
authorities  may  combine  for  the  purpose  of  executing  the  above  provisions 
of  the  Act,  and  they  may  exempt  any  particular  premises  from  visitation; 
they  may  fix  the  number  of  infants  which  may  be  kept  in  a  dwelling,  and 
may  obtain  the  removal  of  any  infant  from  overcrowded,  dangerous,  or 
insanitary  premises,  or  from  the  custody  of  any  negligent,  ignorant, 
drunken,  immoral,  or  criminal  individual.  Offenders  under  this  part  of 
the  Act  are  liable  to  six  months'  imprisonment  or  a  fine,  and  the  above 
provisions  do  not  extend  to  a.ny  relative  or  legal  guardian  of  an  infant. 
The  local  authority  in  London  is  the  County  Council  and  elsewhere  the 
guardians  of  the  poor. 

Part  XL  deals  with  the  prevention  of  cruelty  to  children  and  young 
persons.  When  the  death  of  an  infant  under  three  years  of  age  is  caused 
bv  suffocation  in  a  bed  occupied  by  another  person  of  over  sixteen  years  of 
age,  and  the  other  person  at  the  time  of  going  to  bad  was  under  the  influence 
of  drink,  such  other  person  is  liable,  on  conviction  of  neglect,  to  imprison- 
ment or  fine.  It  is  an  offence  to  cause  any  child  or  young  person  to  beg,  or 
to  fail  to  protect  a  child  under  seven  years  of  age  against  the  risks  from 
burning  in  a  room  where  there  is  an  open  fireplace  grate;  to  allow  children 
or  young  persons  to  be  in  brothels;  or  to  cause  or  favour  the  seduction  or 
prostitution  of  a  girl  under  the  age  of  sixteen.  Where  there  is  an  ofience 
under  this  Act,  a  child  or  young  person  may  be  removed  to  a  "  place  of 
s^fety  "^and  taken  out  of  the  custody  of  a  convicted  person,  and  the  parent 
or  person  liable  to  maintain  the  child  may  bi  made  to  contribute  to  the 
cost  of  maintenance. 

Part  III.  deals  with  juvenile  smoking,  and  imposes  a  penalty  for  selling 
cigarettes  to  children  and  young  persons.     A  constable  or  park-keeper  may 

'  A  workhouse,  hospital,  police  station,  or  other  suitable  place. 


SANITARY   LAW    AND    ADMINISTRATION  70I 

seize  cigarettes  in  the  possession  of  children  and  young  persons,  and  steps 
may  be  taken  to  prevent  cigarettes  being  obtained  from  automatic 
machines,  where  any  such  machine  is  being  extensively  used  by  children 
or  young  persons. 

Part  IV.  deals  with  reformatory  and  industrial  schools;  the  certification, 
inspection,  and  management  of  such  schools;  the  children  liable  to  be  sent 
to  them;  the  power  to  subsequently  apprentice  or  dispose  of  such  children  ; 
the  expenses  of  the  school;  the  establishment  of  day  industrial  schools,  etc. 
Part  V.  deals  with  juvenile  offenders,  and  requires,  inter  alia,  that  a  child 
or  young  person  shall  be  kept  apart  from  adults  during  detention  in  a  police 
station ;  certain  restrictions  are  imposed  as  to  the  punishment  of  children 
and  young  persons,  including  the  abolition  of  the  death  sentence.  The 
provision  of  places  of  detention  is  also  dealt  with. 

Part  VI.  contains  miscellaneous  and  general  clauses.  A  person  giving 
intoxicating  liquor  to  any  child  under  five,  except  in  sickness ;  or  a  publican 
allowing  a  child  to  be  in  the  bar  of  licensed  premises,  except  during  the 
hours  of  closing,  render  themselves  liable  to  a  fine. 

A  very  important  section  (122)  is  the  following:  i.  A  local  education 
authority  may  direct  their  medical  officer,  or  any  person  provided  with,  and, 
if  required,  exhibiting  the  authority  in  writing  of  their  medical  officer,  to 
examine  in  any  public  elementary  school,  provided  or  maintained  by  the 
authority,  the  person  and  clothing  of  any  child  attending  the  school,  and 
if,  on  examination,  the  medical  officer,  or  any  such  authorized  person  as 
aforesaid,  is  of  the  opinion  that  the  person  or  clothing  of  any  such  child  is 
infected  with  vermin,  or  is  in  a  foul  or  filthy  condition,  the  local  education 
authority  may  give  notice  in  writing  to  the  parent  or  guardian  of  or  other 
person  liable  to  maintain,  the  child,  requiring  him  to  cleanse  properly  the 
person  and  clothing  of  the  child  within  twenty-four  hours  after  the  receipt 
of  the  notice. 

2.  If  the  person  to  whom  any  such  notice  as  aforesaid  is  given  fails  to 
comply  therewith  within  such  twenty-four  hours,  the  medical  officer,  or 
some  person  provided  with  and,  if  required,  exhibiting  the  authority  in 
writing  of  the  medical  officer,  may  remove  the  child  referred  to  in  the  notice 
from  any  such  school,  and  may  cause  the  person  and  clothing  of  the  child 
to  be  properly  cleansed  in  suitable  premises  and  with  suitable  appliances, 
and  may,  if  necessary  for  ttiat  purpose,  without  any  warrant  other  than 
this  section,  convey  to  such  premises,  and  there  detain  the  child  until  the 
cleansing  is  effected. 

3.  Where  any  sanitary  authority  within  the  district  of  a  local  education 
authority  have  provided,  or  are  entitled  to  the  use  of,  any  premises  or 
appliances  for  cleansing  the  person  or  clothing  of  persons  infested  with 
vermin,  the  sanitary  authority  shall,  if  so  required  by  the  local  education 
authority,  allow  the  local  education  authority  to  use  such  premises  and 
appliances  for  the  purpose  of  this  section  upon  such  payment  (if  any)  as 
may  be  agreed  upon  between  them,  or,  in  default  of  agreement,  settled  by 
the  Local  Government  Board. 

4.  WTiere,  after  the  person  or  clothing  of  a  child  has  been  cleansed  by  a 
local  education  authority  under  this  section,  the  parent  or  guardian  of, 
or  other  person  liable  to  maintain,  the  child  allows  him  to  get  into  such 
a  condition  that  it  is  again  necessary  to  proceed  under  this  section,  the 
parent,  guardian,  or  other  person  shall,  on  summary  conviction,  be  liable 
to  a  fine  not  exceeding  los. 

5.  Where  a  local  education  authority  give  notice  under  this  section  to 
the  parent  or  guardian  of,  or  other  person  liable  to  maintain,  a  child,  re- 
quiring him  to  cleanse  the  person  and  clothing  of  the  child,  the  authority 
shall  also  furnish  him  with  written  instructions  describing  the  manner  in 
which  the  cleansing  may  best  be  effected. 


702  HYGIENE   AND   PUBLIC    HEALTH 

6.  The  examination  and  cleansing  of  girls  under  this  section  shall  only 
be  effected  by  a  duly  qualified  medical  practitioner,  or  by  a  woman  duly 
authorized,  as  hereinbefore  provided. 

7.  For  the  purpose  of  this  section,  "  medical  officer  "  means  any  officer 
appointed  for  the  purpose  of  Section  1 3  of  the  Education  (Administrative 
Provisions)  Act,  1907. 

For  the  purposes  of  this  Act,  the  expression  "  child  "  means  a  person 
under  the  age  of  fourteen  years,  and  "  young  person  "  one  who  is  between 
fourteen  and  sixteen  years  of  age. 

The  Vaccination  Acts. 

The  Principal  Acts  are  those  of  1867,  1871,  and  1898.  The  Act  of  1867 
required  that  the  parents  or  custodians  of  every  child  born  in  England 
should,  within  three  months  after  its  birth,  take  it  or  cause  it  to  be  taken  to 
the  public  vaccinator  of  the  vaccination  district,  in  which  the  child  resides , 
to  be  vaccinated ;  or  should  within  the  same  period  cause  it  to  be  vaccinated 
by  some  medical  practitioner.  Defaulting  parents  or  custodians  are  liable 
to  prosecution  by  the  vaccination  officer,  who  is  required  to  be  appointed 
by  the  guardians  of  every  union  or  parish  (Act  of  1871).  On  summons, 
magistrates  can  make  an  order  directing  the  child  to  be  vaccinated ;  and 
in  the  event  of  this  order  being  disregarded  the  vaccination  officer  can 
proceed  for  penalties  against  the  defaulter.  The  Act  of  1871  also  rendered 
it  an  offence  for  any  person  to  refuse  to  allow  a  public  vaccinator  to  take 
lymph  from  any  child  that  he  has  vaccinated;  and  also  re-enacted  the 
prohibition  of  inoculating  any  person  with  small-pox. 

The  Act  of  1 898  extends  the  period  within  which  an  infant  may  remain 
unvaccinated  from  three  months  to  six;  nor  need  the  child  be  taken  to  the 
pubhc  vaccinator.  The  public  vaccinator  of  the  district  must  visit  the  home 
of  the  child  for  the  purpose  of  vaccinating  it,  if  the  parent  or  custodian 
so  requires.  If  a  child  is  not  vaccinated  within  four  months  of  its  birth, 
the  public  vaccinator  must,  after  at  least  twenty-four  hours'  notice  to  the 
parent,  visit  the  home  of  the  child,  and  offer  to  vaccinate  the  child  with 
glycerinated  calf  lymph,  or  such  other  lymph  as  may  be  issued  by  the 
Local  Government  Board.  No  child  is  to  be  vaccinated  if,  in  the  opinion 
of  the  public  vaccinator,  the  operation  cannot  be  safely  done,  owing  to  the 
insanitary  condition  of  the  house,  or  the  recent  prevalence  of  infectious 
disease  in  the  district.  In  such  cases  a  certificate  of  postponement  is  to 
be  given,  and  notice  is  to  be  sent  to  the  medical  officer  of  health.  No 
parent  or  custodian  shall  be  liable  to  any  penalty  under  the  Act  of  1867, 
if  within  four  months  from  the  birth  of  the  child  he  satisfies  two  justices  or 
a  stipendiary  magistrate  in  petty  sessions  that  he  conscientiously  believes 
that  vaccination  would  be  prejudicial  to  the  health  of  the  child,  and  within 
seven  days  thereafter  delivers  to  the  vaccination  officer  a  certificate  by  such 
justices  or  magistrate  of  such  conscientious  objection.  The  Act  prohibits 
the  making  of  a  second  order,  directing  that  a  child  shall  be  vaccinated, 
in  the  case  of  any  person  who  has  been  previously  convicted  of  non  com- 
pliance with  a  similar  order  relating  to  the  same  child,  unless  the  child  has 
reached  the  age  of  four  years.  The  Act  also  empowers  the  Local  Govern- 
ment Board  by  Order,  in  the  event  of  serious  risk  of  outbreak  of  small-pox, 
to  require  the  guardians  of  any  poor-law  union  to  provide  vaccination 
stations;  and  to  modify  the  provisions  of  the  Act  as  to  the  visitation  of  the 
child  in  its  own  home  by  the  public  vaccinator. 

The   Vaccination  Act,   1907. 
The  Vaccination  Act  of  1907  has  so  amended  the  Act  of  1898  as  to  sub- 
stitute  a   statutory    "  declaration    of   conscientious    belief "    before   any 
magistrate  for  the  proyjsjon  as  to  satisfying  two  justices,  or  a  stipendiary 


SANITARY    LAW    AND    ADMINISTRATION  703 

magistrate,  of  such  belief  which  formerly  obtained,  and  the  modification 
in  question  came  into  operation  at  the  beginning  of  1908.  The  exemption 
certificate  must  be  sent  within  seven  days  to  the  vaccination  officer. 

The  chief  anomalies  of  the  present  vaccination  law  are  that  the  Acts 
are  administered  by  the  poor-law  guardians,  and  not  by  the  sanitary 
authorities,  who  are  otherwise  charged  with  all  public  health  matters; 
and  that  the  vaccination  officer  is  appointed  by  the  guardians,  but  is 
required  by  the  Local  Government  Board  to  administer  the  Acts  inde- 
pendently of  the  persons  or  board  appointing  him. 

MiDwivES  Act,   1902. 

This  is  an  Act  to  secure  the  better  training  of  midwives  and  to  regulate 
their  practice.  It  prohibits  women,  who  are  not  certified  under  the  Act, 
from  taking  or  using  the  name  or  title  of  midwife,  or  any  name,  title,  or 
description  implying  that  they  are  certified  under  the  Act,  or  specially 
qualified  to  practise  midwifery,  or  recognized  by  law  as  midwives.  Any 
person  so  offending  is  liable  on  summary  conviction  to  a  fine  oi  £s.  After 
April  I,  1910,  no  woman  may  habitually  and  for  gain  attend  women  in 
childbirth  otherwise  than  under  the  direction  of  a  qualified  medical  prac- 
titioner, unless  she  is  certified  under  the  Act.  The  penalty  is  ^10.  For 
two  years  subsequent  to  April  i,  1905,  a  woman  may  claim  to  be  certified 
under  the  Act  if  she  holds  a  certificate  in  midwifery  approved  by  the 
Central  Midwives  Board,  or  produces  satisfactory  proof  that  at  the  passing 
of  the  Act  in  1902,  she  had  been  at  least  one  year  in  bona  fide  practice 
as  a  midwife,  and  bears  a  good  character.  The  Central  Midwives  Board 
consists  of  four  medical  practitioners  and  five  other  persons,  whose  duties 
and  powers  provide  for  the  framing  of  rules  regulating  the  issue  of  certifi- 
cates, the  courses  of  training,  the  conduct  of  examinations  for  certificates, 
and  the  practice  of  midwives,  including  their  suspension  and  the  removal 
of  their  names  from  the  roll  for  disobedience  of  rules. 

The  councils  of  counties  and  county  boroughs  in  England  and  Wales 
are  appointed  as  local  supervising  authorities  over  midwives  within  their 
areas  of  jurisdiction.  These  powers  may  be  delegated  to  any  district 
council  within  the  area  of  the  country.  Besides  a  general  supervision, 
the  supervising  authority  may  investigate  charges  of  malpractice,  or  mis- 
conduct, and  report  to  the  Central  Midwives  Board ;  they  may  suspend 
a  midwife  from  practice,  to  prevent  the  spread  of  infection;  and  keep  a 
current  copy  of  the  roll  of  midwives  accessible  to  public  inspection. 
Prosecutions  for  offences  under  the  Act  may  be  undertaken  by  the  local 
supervising  authority. 

Housing  of  the  Working  Classes. 

The  principal  Act  dealing  with  the  displacement  of  working  class  popu- 
lations from  unhealthy  areas  and  houses,  and  the  rehousing  of  the  displaced 
people,  is  the  Housing  of  the  Working  Classes  Act,  1890. 

Unhealthy  Areas. 

Part  T.  of  the  Act  is  concerned  with  unhealthy  areas.  The  authorities 
for  this  part  of  the  Act  are  the  urban  sanitary  authorities,  and  in  London 
the  London  County  Council  and  the  Corporation  for  the  City. 

A  medical  officer  of  health  is  empowered  to  make  an  official  represen- 
tation to  his  authority — {a)  that  any  houses,  courts,  or  alleys,  are  unfit  for 
human  habitation;  {b)  that  the  narrowness,  closeness,  and  bad  arrange- 
ment, or  the  bad  condition,  of  the  streets  and  houses  or  groups  of  houses 
within  such  area,  or  the  want  of  light,  air,  ventilation,  and  proper  con- 
veniences, or  any  other  sanitary  defects,  or  one  or  more  of  such  causes, 


704  HYGIENE   AND   PUBLIC    HEALTH 

are  dangerous  or  injurious  to  the  health  of  the  inhabitants,  either  of  the 
buildings  in  the  said  area  or  of  the  neighbouring  buildings;  and  that  the 
evils  connected  with  such  houses,  courts  or  alleys,  and  the  sanitary  defects 
in  such  area  cannot  be  effectually  remedied  otherwise  than  by  an  "  im- 
provement "  scheme  for  the  rearrangement  and  reconstruction  of  the 
streets  and  houses  within  such  area. 

The  medical  officer  of  health  may  make  a  representation  on  his  own 
initiative,  or  he  may  be  required  to  make  it  on  the  complaint  of  two  or 
more  justices  of  the  peace  of  the  district,  or  of  twelve  or  more  ratepayers. 
The  local  authority,  on  receiving  the  official  representation,  may  pass  a 
resolution  to  the  effect  that  such  area  is  an  unhealthy  area,  and  that  an 
improvement  scheme  ought  to  be  made  in  respect  of  it.  After  passing 
such  resolution,  they  shall  forthwith  proceed  to  make  a  scheme. 

The  scheme  may  provide  for  the  reconstruction  and  rearrangement  of 
the  streets  and  houses  in  the  area,  and  generally  for  the  opening  out  of  the 
area,  and  the  widening  of  approaches  in  order  to  improve  the  ventilation. 
The  scheme  must  provide  for  proper  sanitary  arrangements,  and  for  such 
dwelling  accommodation  for  the  working  classes  displaced  as  the  Act 
directs.  Due  publicity  must  be  given  to  the  scheme,  and  notices  must  be 
served  on  all  persons  interested.  Application  is  then  made  by  the  sanitary 
authority  to  the  Local  Government  Board  for  a  provisional  order  con- 
lirming  the  scheme.  A  local  inquiry  is  then  held  by  the  Board,  as  to  the 
correctness  of  the  official  representation  and  as  to  the  sufficiency  of  the 
scheme.  A  provisional  order  may  then  be  made  by  the  Board  authorizing 
the  scheme,  and  this  is  subject  to  confirmation  by  Act  of  Parliament. 

In  London,  representation  may  be  made  to  the  London  County  Council 
by  any  medical  officer  of  health  of  a  district,  as  well  as  by  the  county 
medical  officer.  The  confirming  body  is  the  Local  Government  Board, 
and  accommodation  must  be  provided  in  or  near  the  scheduled  area  for 
the  whole  number  of  the  working  classes  displaced.  The  Local  Government 
Board,  however,  if  satisfied  that  there  is  no  necessity  to  rehouse  all  the 
working  classes  on  the  cleared  area,  may  accept  in  substitution  equally 
convenient  accommodation  not  in  or  near  the  area,  and  may  dispense 
with  the  obligation  to  rehouse  to  the  extent  of  one-half  the  number 
displaced. 

Both  in  the  country  and  in  London  this  part  of  the  Act  is  practically 
unworkable.  The  cost  is  prohibitive,  and  the  delays  ensuing  from  the 
complexity  of  procedure  often  allow  of  a  lapse  of  many  years  between 
the  condemnation  of  the  area  and  rebuilding  on  the  cleared  sites. 

Unhealthy  Dwelling  Houses. 

Part  II.  relates  to  individual  unhealthy  dwellings  or  to  small  groups  of 
dwellings.  The  medical  officer  of  health,  on  his  own  initiative,  or  on  the 
requisition  of  four  inhabitant  householders,  makes  an  official  representation 
to  his  authority  that  a  dwelling  house  or  houses  are  in  a  state  so  dangerous 
or  injurious  to  health  as  to  be  unfit  for  human  habitation.  The  authority 
may  then  direct  proceedings  to  be  taken  against  the  owner  before  a  court 
of  summary  jurisdiction  for  the  closure  of  the  houses  so  represented.  The 
court,  on  the  hearing  of  the  summons,  may  make  a  closing  order  for  the 
houses,  and  may  inflict  a  penalty  upon  the  owner  of  ;£2o. 

Under  the  Housing  of  the  Working  Classes  Act,  rqo3,  if  in  the  opinion 
of  the  local  authority  any  dwelling  house  is  not  reasonably  capable  of  being 
made  fit  for  human  habitation,  or  is  in  such  a  state  that  the  occupation 
thereof  should  be  immediately  discontinued,  it  is  not  necessary  to  serve 
notices  on  the  owner  or  occupier  of  the  premises  to  abate  the  nuisance  before 
applying  for  a  summons  for  a  closing  order  (Sec.  8). 

The  owner,   under  this   Act,  of  leasehold  premises,  of  which  less  than 


SANITARY   LAW    AND    ADMINISTRATION  705 

twcnty-onc  ye;irs  is  unexpired,  is  not  tiic  lessee,  but  tlie  yiuuud  kiudioid. 
Consequently  the  ground  landlord  by  this  Act  is  made  responsible  for  the 
condition  of  premises  over  which  he  may  have  no  control  whatever. 

Notice  of  the  closing  order  is  then  served  upon  the  occupying  tenants 
of  the  houses,  with  notice  to  quit.  Defaulting  tenants  who  do  not  vacate 
the  premises  are  liable  to  a  penalty  of  20s.  a  day  during  disobedience; 
but  as  such  tenants  have  seldom  any  goods  to  distrain  upon,  and  magis- 
trates are  reluctant  to  send  them  to  prison,  it  is  usually  exceedingly  difficult 
to  get  rid  of  the  tenants,  who  continue  to  inhabit  the  premises  until  the 
houses  are  pulled  down  around  them. 

If  nothing  has  been  or  is  being  done  to  render  the  closed  dwelling  houses 
lit  for  human  habitation,  and  it  is  represented  to  the  authority  that  the 
continuance  of  the  buildings  is  dangerous  or  injurious  to  the  health  of  the 
public  or  of  the  inhabitants  of  neighbouring  dwelling  houses,  the  authority 
must  pass  a  resolution  that  it  is  expedient  to  order  the  demolition  of  the 
buildings.  Notice  of  this  must  be  served  upon  the  owner,  who  is  entitled 
to  attend  a  meeting  of  the  authority,  to  be  held  not  less  than  one  month 
after  the  service  of  the  notice,  for  the  further  consideration  of  the  resolution, 
when  he  may  state  his  objections  to  the  demolition.  At  this  meeting  an 
order  must  be  made  for  the  demolition  of  the  buildings,  unless  the  owner 
undertakes  to  execute  forthwith  the  works  necessary  to  render  the  houses 
fit  for  human  habitation.  If  the  houses  have  not  been  demolished  within 
three  months  of  the  making  of  the  order,  the  local  authority  may  proceed 
to  demolish  them  themselves. 

Any  person  aggrieved  by  an  order  of  the  local  authority  under  this  part 
(II.)  of  this  Act  may  appeal  against  the  same  to  a  Court  of  Quarter  Sessions. 
Until  this  appeal  has  been  heard  or  ceases  to  be  prosecuted,  the  whole 
procedure  under  the  Act  has  to  stand  still.  This  power  of  appeal  by  any 
aggrieved  person  practically  makes  the  Act  unworkable  if  opposition  is 
encountered.     The  cost  and  the  delays  ensuing  are  prohibitive. 

Under  Part  II.  representation  may  be  made  as  to  "  obstructive  "  build- 
ings— that  is  to  say,  buildings  which  stop  or  interfere  with  the  light  and 
air  about  neighbouring  buildings,  or  which  prevent  measures  being  carried 
into  effect  for  remedying  sanitary  evils  attaching  to  such  buildings.  The 
owner  of  the  obstructive  buildings  is  entitled  to  be  heard  by  the  local 
authority  before  an  order  is  made  for  the  demolition  of  the  buildings.  The 
site  of  the  buildings  may  either  be  purchased  under  compulsory  powers 
or  by  agreement,  and  compensation  is  settled  by  arbitration. 

Improvement  or  reconstruction  schemes  may  be  made  under  this  part 
(II.)  of  the  Act — {a)  in  respect  of  unhealthy  dwelhng  houses  for  which 
demolition  orders  have  been  raade;  {b)  in  the  case  of  unhealthy  areas 
which  are  too  small  to  be  dealt  with  under  Part  I.  The  improvement 
scheme  may  provide  for  the  opening  up  of  the  area,  the  widening  of  streets 
and  approaches,  and  the  reconstruction  and  rearrangement  of  the  buildings 
with  the  erection  of  dwellings  for  the  working  classes. 

The  procedure  is  then  very  much  the  same  as  under  Part  I. — the  appli- 
cation to  the  Local  Government  Board  for  a  provisional  order,  the  holding 
a  local  inquiry,  and  the  making  of  a  provisional  order.  This  order  requires 
no  confirmation  if  the  area  is  purchased  by  agreement.  If  the  land  is  to 
be  acquired  by  compulsory  purchase,  the  order  must  be  published  and 
notice  served  upon  the  owners.  If  within  two  months  after  publication 
there  is  no  petition  by  the  owners,  the  order  may  be  confirmed  by  the 
Board;  but  if  there  is  a  petition,  the  order  is  not  valid  until  confirmed  by 
Act  of  Parliament. 

In  London  it  has  been  customary  for  lengthy  disputes  to  take  place 
between  the  local  district  authorities  and  the  London  County  Council,  as 
to  whether  schemes  of  improvement  oi  unhealthy  areas  should  be  under 

45 


706  HYGIENE   AND   PUBLIC   HEALTH 

Part  I.  or  Part  II.  of  the  Act.  In  the  former  case  the  cost  is  borne  by  all 
ratepayers  of  London  as  a  Metropohtan  improvement,  wliilst  in  the  latter 
the  greater  portion  of  the  cost  becomes  a  local  debt.  In  the  event  of  the 
representation  relating  to  only  ten  houses,  it  must  be  made  under  Part  II. 
In  case  of  dispute  the  Local  Government  Board  has  power  to  appoint  an 
arbitrator  to  decide  as  to  wliether  the  scheme  is  to  be  under  Part  I.  or 
under  Part  II.  In  the  latter  event  the  County  Council  may  be  required 
to  contribute  to  the  expenses  of  the  scheme.  In  consequence  of  the 
disputes,  the  great  cost,  and  the  complexity  of  procedure  and  resulting 
delays,  the  Act  has  been  practically  a  failure. 

Working  Class  Lodging  Houses. 

Part  III.  of  the  Act  relates  to  the  provision  of  working  class  dweUings. 
This  part  of  the  Act  is  now  entrusted  to  the  municipal  boroughs  in  London. 
Prior  to  November,  1900,  the  London  County  Council  was  the  authority. 
In  other  urban  sanitary  districts  Part  III.  may  be  adopted  with  the 
sanction  of  the  Local  Government  Board;  in  rural  sanitary  districts,  it 
may  be  adopted  after  inquiry  by  the  County  Council  as  to  the  necessity 
of  providing  working  class  accommodation  by  parochial  means. 

Land  may  be  acquired  by  a  local  authority  either  by  agreement  or  by 
compulsory  purchase,  as  provided  by  sections  175  to  17S  of  the  Public 
Health  Act,  1875.  On  the  land,  buildings  suitable  for  lodging  houses 
for  the  working  classes  may  be  erected,  fitted,  and  furnished.  The  local 
authority  may  purchase  or  lease  lodging  houses  already  erected  or  to  be 
built. 

The  general  management,  regulation,  and  control  of  the  lodging  houses 
vests  in  the  local  authority,  who  may  make  by-laws  for  this  purpose.  Any 
tenant  in  receipt  of  poor-law  relief  is  disqualilied  from  remaining  a  tenant, 
except  in  case  of  accident  or  temporary  illness. 

Under  the  Housing  of  the  Working  Classes  Act,  1903,  a  local  authority, 
with  the  consent  of  the  Local  Government  Board,  may  provide  a  workshop, 
recreation  ground,  or  other  amenities  for  persons  occupying  a  lodging  house. 

The  Housing  Act  also  contains  the  following  important  provision:  "  In 
any  contract  for  letting  by  habitation  by  persons  of  the  working  classes  a 
house  or  part  of  a  house,  there  shall  be  implied  a  condition  that  the  house 
is  at  the  commencement  of  the  holding  in  all  respects  reasonably  lit  for 
human  habitation."  This  section  applies  to  houses  let  at  a  rental  at  which 
the  rates  may  be  compounded  for — namely,  ;^20  per  annum  in  London, 
and  ;^io  in  the  provinces. 

By  the  Housing  of  the  Working  Classes  Act,  1900,  local  authorities  are 
now  empowered  to  acquire  land  outside  their  own  districts  for  the  purpose 
of  erecting  lodging  houses  for  the  working  classes. 

The  Housing,  Town  Planning,  etc..  Act,   1909. 

Under  this  Act,  Part  III.  of  the  Housing  of  the  Working  Classes  Act, 
1890,  is  extended  to  and  takes  effect  in  every  urban  and  rural  district 
in  which  it  has  not  so  far  been  adopted.  Section  10  provides  that  where 
a  complaint  is  made  to  the  Local  Government  Board  (a)  as  respects  any 
rural  district  by  the  Council  of  the  county,  by  the  Parish  Council,  or  by 
any  four  inhabitant  householders;  or  (b)  as  respects  any  county  district, 
not  being  a  rural  district,  by  the  Council  of  the  county,  or  by  four  in- 
habitant householders;  or  (c)  as  respects  the  area  of  any  other  local 
authority  by  lour  inhabitant  householders  of  the  area,  that  the  local 
authority  have  failed  to  exercise  their  powers  under  Part  II.  or  Part  III. 
of  the  Housing  of  the  Working  Classes  Act,  1890,  in  cases  where  those 
powers  ought  to  have  been  exercised,  the  Local  Government  Board  may 


SANITARY   LAW   AND   ADMINISTRATION 


707 


cause  a  public  local  inquiry  to  be  Iielil,  and,  if  salislicd  that  there  lias 
been  such  a  failure  on  the  part  of  the  local  authority,  may  make  an  order 
directing  that  authority,  within  a  limited  time,  to  carry  out  such  works 
and  do  such  other  things  as  may  be  mentioned  in  the  order  for  the  j)ur- 
pose  of  remedying  tlie  default.  The  Local  Government  Board  must  take 
into  consideration  the  necessity  for  further  accommodation  for  the  housing 
of  the  working  classes  in  the  district,  the  probability  that  the  required 
accommodation  will  not  be  otherwise  provided,  and  the  other  circum- 
stances of  the  case,  and  whether,  having  regard  to  the  liability  whicli  will 
be  incurred  by  the  rates,  it  is  prudent  for  the  local  authority  to  undertake 
the  provision  of  such  accommodation.  Where  the  order  of  the  Lccal 
Government  Board  is  not  complied  with  by  a  District  Council,  the  Local 
Government  Board,  with  the  consent  of  the  County  Council,  instead  of 
enforcing  the  order  against  the  District  Council,  may  make  an  order 
directing  the  County  Council  to  carry  out  the  required  works.  An  order 
naade  by  the  Local  Government  Board  must  be  laid  before  both  Houses 
of  Parliament,  and  may  be  enforced  by  mandamus. 

By  Section  11,  where  it  appears  to  the  Local  Government  Board  that  a 
local  authority  has  failed  to  perform  its  duty  under  the  Housing  Acts  of 
carrying  out  an  improvement  scheme  under  Part  I.  of  the  Act  of  1890  or 
has  failed  to  give  effect  to  any  order  as  respects  an  obstructive  building, 
or  to  a  reconstruction  scheme  under  Part  II.,  or  has  failed  to  cause  to  be 
made  the  inspection  of  its  district  required  by  the  1909  Act,  the  Local 
Government  Board  may  make  an  order  requiring  the  local  authority  to 
remedy  the  default  and  to  carry  out  any  required  works  within  a  fixed 
time.     The  order  also  is  enforceable  by  mandamus. 

Section  1 2  enacts  that  on  complaint  by  a  Parish  Council  or  four  inhabitant 
householders,  a  County  Council  may  hold  an  inquiry  into  the  alleged 
negligence  of  a  Rural  District  Council  to  exercise  its  powers  under  Part  III. 
of  the  1890  Act.  If  satisfied  oi  the  default,  the  County  Council  may 
resolve  that  the  District  Council's  powers  under  Part  III.  be  transferred 
to  itself,  and  such  powers  are  accordingly  transierred.  Under  section  13, 
a  County  Council  may,  after  notice  to  a  Rural  District  Council,  apply  to 
the  Local  Government  Board  for  an  order  conferring  upon  it  the  powers 
conferred  upon  district  councils  by  Part  III.  of  the  1890  Act,  and  the 
Board  may  make  such  an  order. 

Section  14  provides  that  in  any  contract  made  after  the  passing  of  the 
Act  for  letting  for  habitation  a  house  or  part  of  a  house  at  a  rent  not 
exceeding  [a)  in  London  £^0,  [b)  in  a  borough  or  urban  district  with  a 
population  of  50,000  or  upwards  ;/|26,  (f)  elsewhere  £16,  there  shall  be 
implied  a  condition  that  the  house  is  in  all  respects  reasonably  fit  for  human 
habitation,  unless  the  premises  are  let  for  a  term  of  not  less  than  three 
years,  not  determinable  by  either  party  before  the  expiration  of  the  term, 
and  the  lessee  undertakes  to  put  the  premises  into  a  condition  reasonably 
fit  for  occupation. 

Section  15  provides  that  section  14  shall,  as  respects  contracts  to  which 
section  14  applies,  take  effect  as  if  the  condition  implied  by  that  section 
included  an  undertaking  that  the  house  shall,  during  the  holding,  be  kept 
by  the  landlord  in  all  respects  reasonably  fit  for  human  occupation.  If 
it  appears  to  the  local  authority  within  the  meaning  of  Part  II.  of  the  Act 
of  1890  that  the  undertaking  implied  by  virtue  of  this  section  is  not  com- 
plied with,  the  authority  shall,  if  a  closing  order  is  not  made  with  respect 
to  the  house,  by  written  notice  require  the  landlord  within  twent3'-one 
days  to  execute  such  works  as  may  be  necessary  to  make  the  house  in  all 
respects  reasonably  fit  for  human  habitation.  Within  twenty-one  days  after 
the  receipt  of  such  notice  the  landlord  may  by  written  notice  to  the  local 
authority  declare   his   intention   of   closing   the   house,   and   thereupon   a 


708  HYGIENE   AND   PUBLIC   HEALTH 

closing  order  shall  be  deemed  to  have  become  operative  in  respect  of  such 
house.  If  the  notice  given  by  the  local  authority  is  not  complied  with, 
the  authority  may  do  the  work  and  recover  the  expenses  as  a  civil  debt, 
or  the  authority  may  by  order  declare  the  expenses  payable  by  annual 
instalments  in  five  years,  with  5  per  cent,  interest.  The  landlord  is  given 
power  of  appeal  to  the  Local  Government  Board  against  any  notice  requir- 
ing the  execution  of  works,  and  also  against  any  demand  or  order  for  the 
recovery  of  expenses. 

Sections  1 7  and  1 8  amend  the  procedure  of  the  1 890  Act  with  regard  to 
closing  and  demolition  orders.  It  now  becomes  the  duty  of  a  sanitary 
authority,  on  the  representation  of  its  medical  oiKicer  of  health,  that  a 
dwelling  house  is  in  a  state  so  dangerous  or  injurious  to  health  as  to  be 
vmfit  for  human  habitation,  to  make  an  order  prohibiting  the  use  of  the 
dwelling  house  for  human  habitation  until  in  the  judgment  of  the  local 
authority  the  dwelling  house  is  rendered  fit  for  that  purpose.  Notice  of 
a  closing  order  must  be  served  forthwith  on  every  owner  of  the  dwelling 
house,  and  any  owner  aggrieved  by  the  order  may  appeal  to  the  Local 
Government  Board  within  fourteen  days  after  the  order  is  served.  By 
section  49  the  expression  "  owner"  includes  all  lessees  or  mortgagees  of 
any  premises  except  persons  who  are  lessees,  the  original  term  of  whose 
leases  is  less  than  twenty-one  years.  The  local  authority  must  serve  notice 
of  the  closing  order  on  every  occupying  tenant  of  the  dwelling  house,  and 
the  tenant  is  required  to  quit  within  fourteen  days  after  the  service  of  the 
notice.  In  default  of  leaving  the  house,  the  tenant  is  liable  on  summary 
conviction  to  be  ordered  to  quit  the  house  within  a  specilied  time.  The 
local  authority  may  make  to  every  tenant  who  quits  a  reasonable  allow- 
ance for  removal  expenses,  such  sum  to  be  recoverable  from  the  owner. 
If  the  owner  does  not  consent  to  the  amount  determined  by  the  local 
authority,  a  court  of  summary  jurisdiction  may  fix  the  amount.  The 
local  authority  shall  determine  a  closing  order  made  by  them,  if  satisfied 
that  the  dwelling  house  has  been  rendered  fit  for  human  habitation.  If, 
on  the  application  of  any  owner  of  a  dwelling  house  the  local  authority 
refuse  to  determine  a  closing  order,  the  owner  may  appeal  to  the  Local 
Government  Board  within  fourteen  days  of  the  refusal.  A  room  habitu- 
ally used  as  a  sleeping  place,  the  surface  of  the  floor  of  which  is  more  than 
3  feet  below  the  street  adjoining,  shall  be  deemed  to  be  a  dwelling  house 
so  dangerous  or  injurious  to  health  as  to  be  unfit  for  human  habitation  if 
it  is  not  on  an  average  at  least  7  feet  in  height,  or  does  not  comply  with 
regulations  made  by  the  local  authority  or  by  the  Local  Government 
Board  for  securing  the  proper  ventilation  and  lighting  of  such  rooms,  and 
their  protection  from  dampness,  effluvia,  or  exhalation.  The  closing  order 
made  in  respect  of  such  a  room  shall  not  prevent  the  room  being  used  for 
purposes  other  than  those  of  a  sleeping  place. 

Where  a  closing  order  in  respect  of  any  dwelling  house  has  remained 
operative  for  three  months,  the  local  authority  shall  consider  the  question 
of  the  demolition  of  the  house.  Every  owner  of  the  house  must  be  given 
a  month's  notice,  and  is  entitled  to  be  heard  when  the  question  is  con- 
sidered. The  local  authority  ma)'  make  a  demolition  order  if  of  opinion 
that  the  house  has  not  been  rendered  lit  for  human  habitation,  or  that 
the  necessary  steps  are  not  being  taken  to  render  it  fit,  or  that  the  con- 
tinuance of  the  building  is  a  nuisance  or  dangerous  or  injurious  to  the 
health  of  the  public  or  of  neighbouring  inhabitants.  The  operation  of 
the  demolition  order  may  be  postponed  for  six  months  if  the  owner  under- 
takes the  execution  of  the  necessary  works  to  render  the  house  lit  for 
habitation.  Notice  of  a  demolition  order  must  be  forthwith  served  on 
every  owner  of  the  house,  and  any  owner  aggrieved  may  appeal  to  the 
Local  Government  Board  within  twenty-one  days. 


SANITARY   LAW   AND   ADMINISTRATION  709 

Sections  32  and  33  of  the  Act  of  1890  are  repealed,  but  sections  34  and 
35  are  not  repealed.  Section  34  requires  the  owner  to  demolish  a  building 
within  three  months  after  the  demolition  order  becomes  operative;  whilst 
section  35  allows  any  person  aggrieved  by  an  order  of  the  local  authority, 
if  he  is  not  entitled  to  appeal  to  the  Local  Government  Board,  to  appeal 
to  a  court  of  quarter  sessions,  when  all  further  work  and  proceedings  are 
stopped  until  the  appeal  is  determined.  In  the  case  of  owners  of  con- 
demned property  whose  original  leases  are  for  a  less  term  than  twenty-one 
years,  there  is  still  the  same  ability  to  resort  to  appeals,  which  not  only 
may  unduly  prolong  the  proceedings,  but  ma}-  also  involve  heavy  law 
costs. 

Section  43  provides  that  notwithstanding  any  local  Act  or  by-law  in 
force  in  any  borough  or  district,  it  shall  not  be  lawful  to  erect  any  back-to- 
back  houses  intended  to  be  used  as  dwellings  for  the  working  classes,  and 
any  such  house  commenced  to  be  erected  after  the  passing  of  the  Act  shall 
be  deemed  to  be  unfit  for  human  habitation.  Provided  that  nothing  in 
the  section  shall  prevent  the  erection  or  use  of  a  house  containing  several 
tenements  placed  back  to  back,  if  the  medical  officer  of  health  for  the 
district  certifies  that  the  several  tenements  are  so  constructed  and  arranged 
as  to  secure  effective  ventilation  of  all  habitable  rooms  in  every  tenement ; 
nor  does  the  section  apply  to  houses  abutting  on  any  streets  the  plans 
whereof  were  approved  before  iMay  i,  190Q,  in  any  district  in  which  any 
local  Act  or  by-law  permitting  the  erection  of  back-to-back  houses  was 
in  force. 

Part  II.  of  the  Act  deals  with  town  planning.  Section  54  provides  that 
a  town-planning  scheme  may  be  made  in  accordance  with  the  provisions 
of  the  Act  as  respects  any  land  which  is  in  course  of  development,  or 
appears  likely  to  be  used  for  building  purposes,  with  the  general  object 
of  securing  proper  sanitary  conditions,  amenity,  and  convenience  in  con- 
nection with  the  laying  out  and  use  of  the  land,  and  of  any  neighbouring 
lands.  The  Local  Government  Board  may  authorize  a  local  authority 
to  prepare  a  town-planning  scheme  in  respect  of  any  land  within  or  in  the 
neighbourhood  of  their  area,  or  to  adopt,  with  or  without  modifications, 
any  such  scheme  proposed  by  all  or  any  of  the  owners  of  any  land  in- 
volved. A  piece  of  land  already  built  upon,  or  a  piece  of  land  not  likely 
to  be  used  for  building  purposes  may  be  included  in  the  scheme.  A  town- 
planning  scheme  prepared  or  adopted  by  a  local  authority  must  be  ap- 
proved by  an  order  of  the  Local  Government  Board,  and  when  approved, 
it  has  effect  as  if  it  were  enacted  in  the  Act.  In  London  local  authorities 
can  only  prepare  town-planning  schemes  with  the  consent  of  the  London 
County  Council.  The  Local  Government  Board  ma}^  make  regulations 
for  regulating  generally  the  procedure  to  be  adopted  with  reference  to 
town-planning  schemes.  The  Act  includes  provisions  for  compensation 
in  respect  of  property  injuriously  affected  by  a  scheme,  and  where  any 
property  is  increased  in  value  for  the  recovery  by  the  local  authority  of 
one-half  of  the  increase  (betterment).  Local  authorities  are  authorized 
to  purchase  compulsorily  or  by  agreement  any  land  comprised  in  a  town- 
planning  scheme.  If  the  Local  Government  Board  are  .satished  on  any 
representation,  after  holding  a  public  inquiry,  that  a  local  authority  has 
failed  to  take  the  requisite  steps  for  having  a  satisfactory  town-planning 
scheme  prepared  and  approved  in  a  case  where  a  town-planning  scheme 
ought  to  be  made;  or  has  failed  to  adopt  any  scheme  proposed  by  owners 
of  land  in  a  case  where  the  scheme  ought  to  be  adopted ;  or  has  unreason- 
ably refused  to  consent  to  any  modifications  or  conditions  imposed  by 
the  Local  Government  Board,  the  Board  may  order  the  local  authority 
to  prepare  and  submit  for  its  approval  such  a  scheme,  or  to  adopt  the 
scheme,  or  to  consent  to  the  niodifications  or  conditions.     Or  the  Local 


710  HYGIENE    AND    PUBLIC    HEALTH 

Government  Board  may  itself  approve  the  proposed  scheme,  and  there- 
upon the  scheme  shall  have  efEect  as  if  it  had  been  adopted  by  the  local 
authority  and  approved  by  the  Local  Government  Board.  If  a  local 
authority  fails  to  enforce  effectively  the  observance  of  a  scheme  which  has 
been  confirmed,  the  Local  Government  Board  may  order  the  local  authority 
to  enforce  the  scheme  or  any  of  its  provisions,  and  execute  any  works 
required  under  the  scheme.  Any  order  under  this  section  may  be  enforced 
by  mandamus. 

Part  III.  of  the  Act  requires  that  every  County  Council  shall  appoint 
a  medical  officer  of  health  under  section  17  of  the  Local  Government  Act, 
the  duties  to  be  such  as  may  be  prescribed  by  general  order  of  the  Local 
Government  Board,  or  may  be  assigned  by  the  County  Council.  Such 
officer  shall  only  be  removable  with  the  consent  of  the  Local  Government 
Board.  He  shall  have  the  same  powers  of  entrj'  on  premises  as  are  con- 
ferred on  a  medical  officer  of  health  of  a  district.  He  shall  not  be  appointed 
for  a  limited  period  only,  shall  not  engage  in  private  practice,  nor  hold 
any  other  appointment  without  the  express  written  consent  of  the  Local 
Government  Board.  Every  Coimty  Council  in  England,  except  that  of 
London,  must  establish  a  public  health  and  housing  committee,  and  all 
matters  relating  to  public  health  and  the  housing  of  the  working  classes 
must  be  referred  to  that  committee.  The  County  Council  may  delegate 
any  of  its  powers  in  respect  of  public  health  and  housing  to  the  committee, 
except  the  power  of  raising  a  rate  or  borrowing  money,  or  resolving  that 
the  powers  of  a  District  Council  in  default  be  transferred  to  the  County 
Council. 

Customs  and  Inland  Revenue  Act,   1890. 

Section  26  (2)  provides  that  the  assessment  under  the  inhabited  house 
duty  of  any  house  originally  built  or  adapted  by  additions  or  alterations 
and  used  for  the  sole  purpose  of  providing  separate  dwellings  at  rents  not 
exceeding  ys.  6d.  per  week  shall  be  discharged  by  the  Commissioners, 
provided  that  a  certificate  of  the  medical  officer  of  health  of  the  district 
in  which  the  house  is  situate  shall  be  produced  to  them  to  the  efEect  that 
the  house  is  so  constructed  as  to  afford  suitable  accommodation  for  each 
of  the  families  or  persons  inhabiting  it,  and  that  due  provision  is  made 
for  their  sanitary  requirements.  The  medical  officer  of  health  is  required 
to  examine  any  such  house  in  his  district  on  the  request  of  the  person  liable 
to  pay  the  house  duty,  and  if  the  certificate  can  be  properly  given  he  shall 
certify  the  same  accordingly. 

Revenue  Act,   1903. 

The  Revenue  Act,  1903,  exempts  from  inhabited  house  duty  dwelling 
liouses  used  for  the  sole  purpose  of  providing  separate  dwellings  of  an  annual 
value  below  ;^2t).  In  the  case  of  dwelling  houses  of  an  annual  value 
between  ;^2o  and  £40  the  inhabited  house  duty  is  reduced  to  3d.;  and  in 
the  case  of  dwelling  houses  of  ;^40  to  £6v  annual  value,  the  rate  is  reduced 
to  6d.  For  dwelling  houses  of  an  annual  value  below  £40  the  certificate 
of  the  medical  officer  of  health  of  the  district  must  be  produced,  as  pro- 
vided by  section  2O  (2)  of  the  Customs  and  Inland  Revenue  Act,  189(1. 

Movable  Dwellings. 

Under  the  Public  Health  Act,  1875  (section  314)  local  authorities  are 
given  power  to  make  by-laws  for  securing  the  decent  lodging  and  accom- 
modation of  hop  pickers  within  their  district.  By  the  Public  Health 
(I<"ruit  Pickers'  Lodgings)  Act,  18S2,  such  by-laws  may  be  made  applicable 
to  persons  engaged  in  fruit  and  vegetable  picking.     The  Local  Government 


SANITARY    LAW    AND    ADMINISTRATION  711 

Board  has  framed  model  by-laws  suitable  for  tents,  sheds,  barns,  vans,  and 
other  places  occui)ied  as  temporary  dwellin^js.  Under  these  by-laws  the 
habitations  must  be  clean,  dry,  weather  proof,  lighted,  and  ventilated. 
Sixteen  square  feet  of  floor  space  must  be  allowed  for  each  adult,  and  for 
every  two  children  under  ten  years.  There  must  be  arrangements  of 
screens  for  privacy  where  different  sexes  are  accommodated.  Cooking 
places,  adequate  water  supply,  and  privy  accommodation  must  be  pro- 
vided. There  must  be  a  sufficient  supply  of  dry,  clean  straw,  or  other 
bedding.  The  premises  must  be  kept  in  a  cleanly  condition  at  all  times, 
and  limewashed  once  a  year. 

Sections  g  and  10  of  the  Housing  of  the  Working  Classes  Act,  1885,  are 
not  repealed,  and  give  local  authorities  power  to  deal  with  movable  or 
temporary  dwellings  in  their  districts  as  regards  nuisances,  overcrowding, 
etc.,  with  right  of  entry  of  officers,  as  if  they  were  hou.ses  within  the  district. 

Canal  Bo.\ts. 

Under  the  Canal  Boats  Acts  of  1S77  and  1884,  every  canal  boat  used  as 
a  dwelling  must  be  registered  with  the  local  authority  as  a  dwelling  for  a 
certain  number  of  persons  of  specified  age  and  sex,  by  whom  alone  it  is  to 
be  occupied.  The  registration  authorities  are  one  or  more  of  the  sanitary 
authorities  abutting  on  the  canal  on  which  the  canal  boat  plies,  as  may  be 
prescribed  by  the  Local  Government  Board.  Ever}'  canal  boat  when 
registered  must  be  lettered,  marked  "  registered,"  and  numbered  in  a 
conspicuous  manner,  and  must  show  the  name  of  the  place  to  which,  as 
registered,  she  belongs.  On  the  appearance  of  infectious  disease  on  board 
a  canal  boat,  the  boat  maybe  detained  to  be  cleansed  and  disinfected  after 
removal  of  the  case  to  hospital. 

The  Local  Government  Board  is  empowered  to  make  regulations  for 
canal  boats,  which  the  local  authorities  are  required  to  enforce.  These 
regulations  provide  that — There  must  be  at  least  one  dry  and  clean  cabin. 
An  after  cabin  must  contain  not  less  than  i8n  cubic  feet  of  free  air  space, 
and  a  fore  cabin  80  cubic  feet.  There  must  be  ventilation  and  sleeping 
accommodation.  One  cabin  must  contain  a  stove  and  chimney.  There 
must  be  storage  for  3  gallons  of  water.  If  the  boat  carries  foul  cargoes, 
the  hold  must  be  separated  from  an  inhabited  cabin  by  a  double  bulkhead, 
with  an  interspace  of  4  inches,  the  bulkhead  next  the  cargo  being  water- 
tight; the  space  must  be  open  throughout  to  the  external  air  and  provided 
with  a  pump  for  the  removal  of  any  liquid  from  such  space.  There  must 
be  60  cubic  feet  of  air  space  per  head  for  persons  over  twelve  years,  and 
40  cubic  feet  for  children  under  twelve.  No  boy  above  fourteen  or  girl 
above  twelve  may  sleep  in  a  cabin  occupied  by  a  married  couple ;  and  males 
over  fourteen  and  females  over  twelve  must  not  sleep  in  the  same  cabin 
imless  married.  The  interior  of  the  cabin  must  be  repainted  every  three 
years  and  kept  clean.  Bilge  water  must  be  pumped  out  daily.  The  master 
of  the  boat  must  notify  the  occurrence  of  infectious  disease  to  the  sanitary 
authority  of  the  district  he  may  be  in,  and  to  the  sanitary  authority  of 
the  district  of  his  destination;  and  if  his  boat  is  detained  for  disinfection, 
he  may  not  proceed  until  he  has  obtained  a  medical  certificate  of  cleansing 
and  disinfection. 

Factories  and  Workshops. 

Generally  speaking,  factories  are  places  where  mechanical  power  is 
used — that  is  to  say,  where  engines  are  employed  worked  by  steam,  gas, 
water,  or  electricity.  These  are  under  the  control  of  the  Secretary  of 
State  for  the  Home  Department,  and  are  inspected  by  factory  -inspectors 
appointed  by  him. 

Workshops  are  places  where  mechanical  power  is  not  used,  and,  so  far 


712  HYGIENE    AND   PUBLIC   HEALTH 

as  regards  sanitation,  are  supervised  by  ol'ticers  of  the  local  sanitarj' 
authorities.  There  are,  however,  a  large  nmnber  of  non-textile  factories 
which  are  controlled  by  the  Home  Secretary  whether  mechanical  power  is 
employed  in  them  or  not.  These  are  blast  furnaces,  copper  mills,  iron 
mills,  foundries,  manufactories  of  earthenware,  lucifer  matches,  percussion 
caps,  cartridges,  tobacco,  paper,  glass,  print  works,  fustian  cutting, 
printing,  bookbinding,  and  flax  scutch  mills. 

Piihlic  Health  Act,  1875. 

Section  qi  defines  as  a  nuisance  any  factory,  workshop,  or  work-place — 
not  already  imder  the  operation  of  any  general  Act  (Factory  and  ^^'ork- 
shops  Acts,  1878,  1883,  1891,  and  1895^)  for  the  regulation  of  factories 
or  bakehouses — not  kept  in  a  cleanly  state,  or  not  ventilated  in  such  a 
manner  as  to  render  harmless,  as  far  as  practicable,  any  gases,  vapours, 
dust,  or  other  impurities  generated  in  the  course  of  the  work  carried  on 
therein  that  are  a  nuisance  or  injurious  to  health,  or  so  overcrowded  while 
work  is  carried  on  as  to  be  dangerous  or  injurious  to  the  health  of  those 
employed  therein. 

By  section  38  local  authorities  may  require  in  factories  or  workshops  a 
sufficient  number  of  water-closets,  earth-closets,  or  privies  and  ashpits, 
for  the  separate  use  of  each  sex. 

Private  houses  which  are  work-places,  and  in  which  no  mechanical 
power  is  used,  and  in  which  the  workers  are  members  of  the  same  family 
inhabiting  the  house,  are  exempt. 

Similar  provisions  are  in  force  in  the  Metropolis. 

Factory  and  Workshop  Act,  1901. 

This  Act  repeals  the  Factory  and  Workshop  Acts  of  1878  and  1883. 
It  also  repeals  the  Act  of  1891  except  sections  8,  9,  10,  and  12,  and  the  first 
schedule,  and  the  Act  of  1895  except  section  12,  sub-section  3  of  section  24, 
and  section  28. 

The  Act  is  divided  into  Parts.  Part  I.  deals  with  health,  safet}^,  and 
accidents.  Part  II.  deals  with  employment  (hours,  holidays,  overtime, 
night  work,  fitness  for  employment,  etc.) ;  Part  III.  with  the  education 
of  children;  Part  IV.  with  dangerous  and  unhealthy  trades;  Part  V. 
with  tenement  factories,  cotton  cloth  and  other  humid  factories,  bake- 
houses and  laundries;  Part  VI.  with  home  work;  Part  VII.  with  work 
and  wages;  Part  VIII.  with  administration;  Part  IX.  with  legal  pro- 
ceedings; and  Part  X.  is  supplementary. 

The  term  "  owner  "  carries  the  same  interpretation  as  that  given  in 
the  Public  Health  Act,  1875. 

Every  factory  as  defined  by  the  Act,  except  a  domestic  factory,  (a)  must 
be  kept  in  a  cleanly  state;  [b)  must  be  kept  free  from  effluvia  arising  from 
any  drain,  water-closet,  earth-closet,  privy,  or  urinal,  or  other  nuisance; 
(c)  must  not  be  so  overcrowded  while  work  is  carried  on  therein  as  to  be 
dangerous  or  injurious  to  the  health  of  the  persons  employed  therein; 
{d)  must  be  ventilated  in  such  a  manner  as  to  render  harmless,  so  far  as  is 
practicable,  all  the  gases,  vapours,  dust,  or  other  impurities  generated  in 
the  course  of  the  manufacturing  process  or  handicraft  carried  on  therein, 
that  may  be  injurious  to  health.  All  the  walls  and  ceilings  of  rooms, 
passages,  and  staircases  in  a  factory  must  be  limewashed  every  fourteen 
months,  but  painted  or  varnished  surfaces  may  at  similar  intervals  be 
washed  instead  with  hot  water  and  soap,  if  the  paint  or  varnish  is  renewed 
every  seven  years. 

1  Now  repealed  by  the  Act  of  1901. 


SANITARY    LAW    AND    ADMINISTRATION  713 

Workshops  and  \vork-j)lnccs'  must  be  kcjit  in  a  cleanly  state  and  venti- 
lated, and  must  not  be  overcrowded,  and  they  must  be  kept  free  from 
drain,  etc.,  eflluvia.  A  medical  ofiiccr  of  health  or  inspector  of  nuisances 
may  certify  that  the  cleansing  of  a  workshop  is  necessary  for  the  health 
of  the  workers,  and  the  sanitary  authority  must  then  give  notice  to  the 
owner  or  occupier  to  carry  out  the  necessary  works. 

A  factory  or  workshop  is  overcrowded  if  there  is  less  than  250  cubic 
feet  of  space  per  head,  and  less  than  400  cubic  feet  if  overtime  is  being 
worked.  A  notice  must  be  fixed  in  every  factory  and  workshop  specifying 
the  number  of  persons  who  may  be  employed  in  each  room.  The  Secretary 
of  State  may  supersede  the  local  sanitary  authority,  if  default  has  been 
made  by  the  latter  in  carrying  out  any  of  the  provisions  of  the  Act,  which 
it  is  its  duty  to  enforce,  and  may  recover  from  the  authority  all  expenses 
so  incurred.  If  a  factory  inspector  deems  that  there  is  any  act  or  default 
or  neglect  in  relation  to  the  sanitary  arrangements  of  a  factory  or  workshop 
remediable  under  the  Public  >Iealth  Act,  he  must  give  notice  of  the  same 
to  the  sanitary  authority  of  the  district.  It  then  becomes  the  duty  of 
the  sanitary  authority  to  make  such  inquiry,  and  to  take  such  action, 
within  one  month  of  the  receipt  of  the  notice,  as  may  be  necessary  to 
enforce  the  law,  and  also  to  inform  the  factory  inspector  of  the  proceedings 
taken.  In  case  of  default  by  the  sanitary  authority,  the  factory  inspector 
may  himself  take  the  necessary  proceedings,  and  recover  the  expenses 
incurred  from  the  sanitary  authority. 

In  every  factory  and  workshop  adequate  measures  must  be  taken  for 
securing  and  maintaining  a  reasonable  temperature-  in  each  room  in  which 
any  person  is  employed,  but  the  measures  so  taken  must  not  interfere 
with  the  purity  of  the  air  of  the  room.  By  special  order  of  the  Secretary 
of  State,  thermometers  may  be  required  to  be  provided,  and  maintained  in 
working  order,  in  such  places  as  may  be  specified  in  the  order.  In  every 
room  in  any  factory  or  workshop  sufficient  means  of  ventilation  must  be 
provided,  and  sufficient  ventilation  must  be  niaintained.  A  standard  of 
sufficient  ventilation  may  be  prescribed  for  any  class  of  factories  or  work- 
shops by  the  Secretary  of  State.  A  workshop  which  is  not  ventilated 
in  accordance  with  this  section  is  deemed  a  nuisance  under  the  Public 
Health  Act. 

Factories  or  workshops  in  which  the  floors  are  wet  must  be  provided  with 
means  of  drainage.  Workshops  with  undrained  wet  floors  are  a  nuisance 
under  the  Public  Health  Act. 

Every  factory  and  workshop  miist  be  provided  with  sufficient  and 
suitable  sanitary  conveniences  for  the  workers,  and  with  separate  accom- 
modation where  both  sexes  are  employed.  The  Secretary  of  State  by 
special  order  may  determine  what  is  sufficient  and  suitable  accommo- 
dation. 

By  the  Sanitary  Accommodation  Order  of  4th  February,  1903,  it  is 
provided  (i)  That  in  factories  or  workshops  where  females  are  employed 
there  shall  be  one  sanitary  convenience  for  every  25  females.  Where  males 
are  employed  there  shall  be  one  sanitary  convenience  for  every  25  males, 
but  where  the  number  of  males  exceeds  100,  and  sufficient  urinal  accom- 
modation is  also  provided,  there  may  be  one  sanitary  convenience  for 
every  25  males  up  to  the  first  100,  and  one  for  every  40  after.  Where 
the  number  of  males  employed  exceeds  500,  and  the  District  Inspector 
of  Factories  certifies  that  there  is  proper  super\'ision  and  control  in  regard 


1  A  "  work-place  "  has  been  held  to  include  stable-yards,  kitchens  of 

restaurants,  etc. 

-  This  is  not  defined  in  the  Act,  but  it  has  been  held  bv  the  Courts  that 
the  minimum  temperature  should  be  60°  F. 


714  HYGIENE    AND   PUBLIC    HEALTH 

to  the  use  of  the  conveniences  exercised  by  officers  specially  appointed 
for  that  purpose,  one  sanitary  convenience  for  every  60  males  is  sufficient 
in  afldition  to  sufficient  urinal  accommodation.  Any  number  of  persons 
less  than  25,  40,  or  60,  as  the  case  may  be,  must  be  reckoned  as  25,  40,  or  60. 

(2)  Every  sanitary  convenience  must  be  kept  in  a  cleanly  state,  suffi- 
cienth'  lighted  and  ventilated,  and  must  not  commimicate  with  any 
workroom  except  through  the  open  air  or  through  an  intervening  ventilated 
space.  This  latter  provision  need  not  apply  to  workrooms  in  use  prior 
to  January  i,  iqoj,  which  are  mechanically  ventilated  in  such  manner 
that  air  cannot  be  drawn  into  the  workroom  through  the  sanitary  con- 
venience. 

(5)  Every  sanitary  convenience  must  be  under  cover,  and  so  partitioned 
off  as  to  secure  privacy,  and  if  for  the  use  of  females  must  have  a  proper 
door  and  fastenings. 

(4)  The  sanitary  conveniences  must  be  conveniently  accessible  to  all  the 
persons  employed  in  the  factor}'  or  workshop. 

(t)  Where  persons  of  both  sexes  are  employed,  the  conveniences  for 
each  sex  must  be  so  placed  or  so  secured  that  the  interior  shall  not  be 
visible  when  the  door  is  open,  from  any  place  where  persons  of  the  other 
sex  have  to  work  or  pass.  If  the  conveniences  for  one  sex  adjoin  those  of 
the  other  sex,  the  approaches  must  be  separate. 

Factories  and  ^vorkshops  in  which  there  is  an  infringement  of  the  above- 
mentioned  provisions  of  the  Act  are  deemed  not  to  be  kept  in  conformity 
with  the  Act,  and  the  occupier  is  liable  to  a  /lo  fine. 

The  Secretary  of  State  has  power  by  special  order  to  modify  many  of 
the  above-mentioned  provisions,  where  he  deems  it  necessary. 

The  Sanitary  Accommodation  Order  does  not  apply  to  London. 

Every  local  authority  is  required  to  keep  a  register  of  the  workshops 
within  its  district,  and  the  factory  inspector  is  required  to  forward  to  a 
local  authority  any  notice  received  by  him  of  the  commencement  of  any 
workshop  within  the  district  of  such  authority. 

The  medical  officer  of  health  of  every  district  council  and  metropolitan 
borough  must,  in  his  annual  report,  report  specificall}'  on  the  adminis- 
tration of  the  Act  in  workshops  and  workplaces,  and  send  a  copy  of  such 
report  to  the  Secretary  of  State. 

A  medical  officer  of  health  who  becomes  aware  that  any  child  imder  14, 
young  person  between  14  and  18,  or  woman  over  18,  is  employed  in  a 
workshop  or  bakehouse,  must  give  written  notice  of  the  fact  to  the  factory 
inspector. 

The  Act  applies  to  the  Metropolis  as  well  as  to  England  generally,  and 
came  into  operation  on  January  i,  1902. 

Dangerous  and  Uniiealthy  Industries. 

By  the  Act  of  iqoi  every  medical  practitioner  attending  on,  or  called  in 
to  visit  a  patient  whom  he  believes  to  be  suffering  from  lead,  phosphorus, 
arsenical  or  mercurial  poisoning  or  anthrax,  contracted  in  any  factory 
or  workshop,  must  send  to  the  Chief  Inspector  of  Factories  in  London 
a  notice  stating  the  name  and  address  of  the  patient,  and  the  disease  from 
which  he  is  suffering. 

In  any  factory  or  workshop  where  grinding,  glazing  or  polishing  on  a 
wheel,  or  any  process  is  carried  on,  by  which  dust  or  impurities  are  gener- 
ated and  inhaled  by  the  workers  to  an  injurious  extent,  the  factory  in- 
spector may  require  the  use  of  fans  or  other  mechanical  means  to  prevent 
such  inhalation. 

In  every  factory  or  workshop  where  lead,  arsenic,  or  other  poisonous 
substance  is  used,  suitable  washing  conveniences  must  be  provided  for 
the  use  of  the  workers,  and  the  latter  must  not  be  allowed  to  take  their 


SANITARY    LAW    AND    AnMINISTRATION  715 

meals,  or  to  remain  during  meal  lime^^,  in  any  room  where  snch  substances 
are  used. 

The  following  industries  have  been  scheduled  by  the  Secretary  of  State 
as  dangerous  to  life  and  health.  The  manufacture  of  white  lead,  paints, 
and  colours ;  the  extraction  of  arsenic ;  the  enamelling  of  iron  ]>lates  ; 
the  manufacture  of  lucifer  matches  except  such  as  are  made  with  red  or 
amorphous  phosphorus;  the  manufacture  of  earthenware;  the  manu- 
facture of  explosives  in  which  di-nitro-benzole  is  used;  chemical  works; 
quarries;  the  making  of  red,  orange,  or  yellow  lead;  lead  smelting;  tinning 
or  enamelling  of  iron  hollow  ware;  electric  accumulator  works;  flax  mills 
and  linen  factories. 

Power  is  given  to  the  Secretary  of  State  to  make  regulations  in  respect  of 
an}'  dangerous  or  unhealthy  trade,  such  regulations  requiring  the  adoption 
of  special  precautionary  measures  as  regards  cleanliness,  ventilation, 
extraction  of  dust,  etc. 

Cotton  Cloth  and  Other  Humid  Factories. 

The  amount  of  moisture  that  is  permissible  in  these  factories  is  regulated 
by  the  4th  schedule  of  the  Act  of  iqoi,  which  states  the  maximum  humitlity 
permissible  at  temperatures  (dry  bulb)  ranging  from  35°  F.  to  U)f)°  F. 
The  Act  also  requires  dry  and  wet  bulb  thermometers  to  be  provided  and 
maintained  in  all  factories  where  artificial  humidity  is  produced,  and  the 
readings  of  such  thermometers  to  be  recorded  three  times  a  day.  In 
such  factories  the  arrangements  for  ventilation  shall  be  such  that  during 
working  hours  the  CO,  in  the  air  in  any  part  of  the  factory  must  not 
exceed  9  parts  per  10,000  of  air;  nor  must  the  temperature  of  any  room 
in  the  factory  be  raised  by  artificial  means  above  70°  F.,  except  in  so  far 
as  may  be  necessary  in  the  process  of  giving  artificial  humidity  to  the 
atmosphere. 

Outworkers. 

Ill  certain  special  industries  specified  by  order  of  the  Secretary  of  State, 
the  occupiers  of  factories  and  workshops  and  contractors  employed  by 
them,  are  required  to  keep  lists  of  outworkers,  i.e.,  persons  who  do  work 
for  their  employers  outside  the  factory  or  workshop,  and  generally  in  their 
own  homes.  Copies  of  these  lists  must  be  sent  twice  a  year  to  the  sanitary 
authority  of  the  district  in  which  the  factory  or  workshop  is  situate. 
These  lists  must  be  examined  by  the  sanitary  authority,  and  the  names 
and  addresses  of  outworkers  not  residing  in  the  district  of  the  sanitary 
authority  must  be  sent  to  the  sanitary  authority  of  the  district  in  which 
they  do  reside.  These  lists  of  outworkers  kept  by  the  occupier  or  con- 
tractor must  be  open  to  inspection  by  any  factory  inspector  or  officer  of 
the  sanitary  authority.  A  sanitary  authority  may  give  notice  to  the 
occupier  or  contractor  that  the  place  where  the  work  is  carried  on  by  an 
outworker  is  injurious  to  the  health  of  the  persons  employed  therein.  The 
occupier  or  contractor  must  then  cease,  within  one  month  of  the  notice, 
to  give  out  work  to  be  done  in  that  place.  No  wearing  apparel  may 
knowingly  be  given  out  by  any  occupier  or  contractor  to  be  made,  cleaned, 
or  repaired,  by  an  outworker  who  lives  in  a  house  where  there  is  a  case  of 
small-pox  or  scarlet  fever.  The  sanitary  authority  may  make  an  order 
forbidding  any  work  to  be  given  to  an  outworker  residing  in  a  house  of 
which  any  inmate  is  suffering  from  a  notifiable  infectious  disease.  This 
applies  cliiefl}'^  to  the  making,  mending,  cleaning,  etc.,  of  wearing  apparel. 

Domestic  workshops  are  private  houses  or  rooms,  which  are  used  also  as 
dwellings,  and  in  which  the  only  persons  employed  are  members  of  the 
same  familv  dwelling  there.  They  are  exempt  from  the  great  majority 
of  the  provisions  of  the  Factory  and  Workshop  Act,  1901. 


7l6  HYGIENE    AND    PUBLIC    HEALTH 


Bakehouses. 

The  law  (Factory  and  Workshops  Act,  1901)  as  regards  retail  bake- 
houses is  administered  by  the  sanitary  authorities.  A  retail  bakehouse 
is  a  place  in  which  bread  is  baked,  and  is  sold  by  retail  in  a  shop  occupied 
with  the  bakehouse.  The  officers  of  a  sanitary  authority  have  right  of 
access  to  a  retail  bakehouse  at  any  hour  of  the  day  or  night.  All  the  walls 
and  ceilings  of  a  bakehouse,  and  all  passages  and  staircases,  must  be  lime- 
washed  twice  a  year,  or  if  painted  must  be  repainted  every  seven  years, 
and  washed  with  hot  soap  and  water  every  six  months.  Ko  room  on  the 
same  floor  may  be  occupied  as  a  sleeping  room,  unless  completely  separated 
by  a  partition  from  the  bakehouse,  and  provided  with  a  window  at  least 
9  square  feet  in  area,  half  of  which  is  made  to  open.  No  water-closet  or 
privy  is  to  be  within  the  bakehouse,  or  to  communicate  directly  with  it. 
The  cistern  supplying  water  to  a  bakehouse  must  not  supply  a  water-closet. 
No  soil  drain  or  drain  inlet  to  a  soil  drain  may  be  within  the  bakehouse. 
An  underground  bakehouse  shall  not  be  used  unless  it  was  in  use  at  the 
passing  of  the  Act  of  1901.  An  underground  bakehouse  is  one  of  which 
the  floor  surface  is  more  than  3  feet  below  the  footway  of  the  adjoining 
street  or  ground.  Since  January  i,  1904,  an  underground  bakehouse  shall 
not  be  used  unless  certified  by  the  sanitary  authority  to  be  suitable  for 
the  purpose.  No  certificate  may  be  given  unless  the  sanitary  aiithority 
is  satisfied  that  the  bakehouse  is  suitable  as  regards  construction,  light, 
ventilation,  etc.  In  London  no  underground  bakehouses  can  be  used 
unless  so  used  prior  to  January  i,  1S96. 

By  an  order  of  the  Secretary  of  State  of  December  30,  1903,  in  under- 
ground bakehouses  500  cubic  feet  of  space  are  required  for  every  person, 
whilst  in  above-ground  bakehouses,  where  work  is  carried  on  at  night  by 
artificial  light  other  than  electric  light,  between  9  p.m.  and  6  a.m.,  400  cubic 
feet  of  space  are  required  for  every  person. 

I-uundnes. 

The  provisions  of  the  Factory  and  \\'orkshop  Act  of  1901  apply  to 
laundries  carried  on  by  way  of  trade,  or  for  purposes  of  gain.  The  ex- 
emptions are  laundries  worked  by  the  inmates  of  prisons,  reformatories, 
industrial  schools,  or  institutions  conducted  in  good  faith  for  religious 
or  charitable  purposes,  or  worked  by  members  of  the  same  family  dwelling 
in  the  laundry,  in  which  not  more  than  two  persons  dwelling  elsewhere  are 
employed.  Laundries  in  which  steam,  water,  or  other  mechanical  power 
is  used  in  aid  of  the  laundrj-  process  are  factories.  All  other  laundries  are 
workshops. 

In  steam  laundries  (factories),  fans  or  other  means  must  be  provided 
and  used  for  regulating  the  temperature  in  every  ironing  room,  and  for 
carrying  away  the  steam  in  every  washhouse.  All  stoves  for  heating  irons 
must  be  sufficiently  separated  from  any  ironing  room,  and  gas  irons  emitting 
noxious  fumes  must  not  be  used.  The  floors  must  be  kept  in  good  con- 
dition and  drained  so  as  to  allow  water  to  flow  off  freeh'. 

The  Factory  and  Workshops  Act,  1907. 

This  Act  amends  the  Factory  and  Workshops  Act  of  1901  with  respect 
to  laundries,  and  it  extends  that  Act  to  certain  institutions.  Some 
further  conditions  as  to  the  hours  of  employment  of  women  and  young 
persons  in  laundries  are  included.  The  provisions  of  the  principal  Act 
are  made  to  apply  to  institutions  carried  on  for  charitable  or  reformatory 
purposes,  and  not  being  premises  subjected  to  inspection  by  Government 


SANITARY   LAW   AND   ADMINISTRATION  717 

olficials.  If,  lunvevcT,  any  institution  can  satisfy  tlic  Secit-tary  of  State 
that  the  only  persons  working  tlierein  arc  inmates  of  and  su])])orted  by 
the  institution  or  persons  engaged  in  the  supervision  of  the  work  or  manage- 
ment of  machinery,  and  that  such  laundry  work  is  carried  on  in  j^ood  faith 
with  the  purpose  of  the  support,  education,  training  or  reformation  of 
persons  engaged  in  it,  the  Secretary  of  State  may,  by  Order,  direct  that 
the  principal  Act  shall  apply  to  the  institution  subject  to  certain  modifi- 
cations. 

The  Secretary  of  State  may  arrange  that  premises  which  are  subject  to 
inspection  under  any  Government  department,  and  which  are  not  factories 
or  worksliops  (because  the  work  carried  on  tlierein  is  not  with  the  object 
of  trade  or  gain),  shall,  as  respects  matters  dealt  with  by  the  iirincijuil 
Act,  be  inspected  by  a  factory  inspector,  and  that  the  latter  shall  have  the 
usual  rights  of  entry. 

The  White  Phosphorus  Matches  Prohibition  Act,  1908. 

By  this  useful  piece  of  public  health  legislation  no  person  may  use  white 
phosphorus  in  the  manufacture  of  matches,  nor  sell,  offer  for  sale,  or  import 
such  matches. 

Alkali,  Chemical,  and  Other  Works. 

I'lie  works  which  are  subject  to  the  Alkali,  etc.,  Works  Regulation  Acts, 
1891  and  1882,  include  alkali  works  in  which  muriatic  gas  (HCl)  is  evolved, 
sulphuric  acid,  chemical  manure,  gas  liquor,  nitric  acid,  ammonia, 
chlorine,  arsenic,  muriatic  acid,  nitrate  and  chloride  of  iron,  tar,  and 
zinc  works;  also  the  following,  imless  no  H2S  is  evolved,  namely,  alkali 
waste,  barium,  strontium,  antimony  sulphide,  and  bisulphide  of  carbon 
works. 

All  these  works  must  be  registered  by  the  Local  Government  Board. 
In  alkali  works  95  per  cent,  of  the  HCl  gas  evolved  must  be  condensed,  and 
not  more  than  I  grain  of  HCl  gas  per  cubic  foot  of  air,  smoke,  or  chimney 
gases  must  escape  from  the  works.  Sulphurous  acid  and  nitrous  gases 
must  not  be  present  in  escaping  air  or  smoke  to  a  greater  amount  than  the 
equivalent  of  4  grains  of  SOo  per  cubic  foot,  at  a  temperature  of  60°  F., 
and  at  30  inches  barometric  pressure.  Acid  drainage  must  not  be  allowed 
to  mix  with  alkali  waste  so  as  to  cause  a  nuisance,  and  means  must  be 
taken  to  prevent  nuisance  from  alkali  waste.  Similar  regulations  apply 
to  the  sulphuric  acid  and  other  works  enumerated  above;  and  in  all  cases 
the  best  available  means  must  be  adopted  to  prevent  the  escape  of  noxious 
gases  and  to  render  them  harmless  and  inoffensive. 


Adulteration  of  Food  and  Drugs. 

There  are  three  Acts  now  in  force  relating  to  this  subject,  namely,  the 
Sale  of  Food  and  Drugs  Act,  1875;  the  Sale  of  Food  and  Drugs  Act 
Amendment  Act,  1879;  and  the  Sale  of  Food  and  Drugs  Act,  1899. 

For  the  purposes  of  these  Acts,  the  term  "  food  "  includes  every  article 
used  for  food  or  drink  by  man,  other  than  drugs  or  water,  and  any  article 
which  ordinarily  enters  into  or  is  used  in  the  composition  or  preparation 
of  human  food,  and  also  includes  flavouring  matters  and  condiments. 
The  term  "  drugs  "  includes  medicines  for  internal  or  external  use. 

These  Acts  prohibit:  (i)  The  mixing,  colouring,  staining,  or  powdering 
any  article  of  food  with  any  ingredient  or  material  so  as  to  render  the 
article  injurious  to  health,  with  the  intent  that  the  same  may  be  sold  in 
that  state;  and  no  article  so  mixed  may  be.  sold ;  penalty  for  contraven- 
tion, £50   (section  3,   1875  Act).      (2)   The  mixing,  colouring,  staining,  or 


yi8  HYGIENE    AND    PUBLIC    HEALTH 

powdering  any  drug  with  any  ingredient  or  material  so  as  to  atfect  in- 
juriously the  quality  or  potency  of  such  drug;  and  no  drug  so  mixed  may 
be  sold;  penalty,  £s<J-  provided  that  no  person  shall  be  liable  to  be  con- 
victed if  he  proves  that  he  was  unaware  at  the  tinie  of  sale  of  the  food  or 
drug  that  these  were  so  mixed  or  coloured  (section  4,  1875  Act).  (3)  The 
sale,  to  the  prejudice  of  the  purchaser,  of  any  article  of  food  or  any  drug 
which  is  not  of  the  nature,  substance,  and  quality  of  the  article  demanded 
by  such  purchaser;  penalty,  £-0.  Where  any  matter  has  been  added  to 
the  food  or  drug,  thei^e  is  no  offence  if  the  same  has  not  been  fraudu- 
lently used,  but  is  required  tor  preparing  the  food  or  drug  as  an  article  of 
commerce;  neither  does  this  section  apply  to  proprietary  or  patented 
medicines  or  foods  (section  6,  1875  Act).  Under  this  section  a  great 
majority  of  the  prosecutions  for  adulteration  are  instituted.  By  the 
1879  Act  it  is  provided  that  it  shall  be  no  defence  to  a  prosecution  that 
the  purchaser,  having  bought  only  for  analysis,  was  not  prejudiced  by 
the  sale;  neither  is  it  a  valid  defence  to  prove  that  the  food  or  drug  pur- 
chased, though  defective  in  nature,  or  in  substance,  or  in  quality,  was  not 
defective  in  all  three  respects. 

Section  7  of  the  1875  Act  prohibits  the  sale  of  any  compoimd,  article 
of  food,  or  compounded  drug  which  is  not  composed  of  ingredients  in 
accordance  with  the  demand  of  the  purchaser;  penalty,  £20.  By  this 
section,  the  making  up  of  medicines  in  accordance  with  prescription  can 
be  insisted  upon,  and  the  section  is  chiefly  of  value  for  that  purpose. 
With  regard  to  the  sale  of  drugs  and  medicines,  these  articles  must  be  in 
accordance  with  the  requirements  of  the  last  published  edition  of  the 
British  l-'liarmacopoeia,  both  as  regards  the  presence  of  particular  in- 
gredients, their  relative  proportions,  and  their  strengths. 

By  section  8  of  the  1875  Act,  in  the  sale  of  articles  of  food  or  drugs  which 
are  mixed  with  other  ingredients  which  are  not  injurious  to  health  and 
not  fraudulently  added,  there  is  no  offence  if  the  article  sold  has  a  label 
on  it  distinctly  and  legibly  written  or  printed  to  the  effect  that  the  same 
is  "  mixed."  This  label  must  not  be  obscured  b)'  other  matter  on  it 
(section  12,  1899  Act). 

By  section  9  of  the  1875  Act,  no  person  shall,  with  the  intent  that  the 
same  may  be  sold  in  its  altered  state,  without  notice,  abstract  from  an 
article  of  food  any  part  of  it  so  as  to  afEect  injuriously  its  quality,  substance, 
or  nature;  and  no  person  shall  sell  any  article  so  altered  without  making 
disclosure  of  the  alteration;  penalty,  ;/^2o.  This  section  is  invoked  in  cases 
of  prosecution  for  selling  skimmed  or  separated  milk. 

The  1875  Act  provides  for  the  appointment  of  public  analysts  by  local 
authorities,  and  for  the  analysis  of  articles  of  food  and  drugs  submitted 
to  them  by  private  purchasers  (on  payment  of  a  fee  of  los.  6d.),  as  well  as 
by  inspectors  appointed  under  the  Act  to  purchase  samples  for  analysis. 
The  form  of  certificate  to  be  given  bj'  the  public  anah'st  is  set  out  in  the 
schedule  to  the  Act.  In  this  certificate,  in  the  case  of  adulterated  articles 
containing  foreign  ingredients,  the  public  analyst  is  required  to  state  the 
parts  or  percentages  of  foreign  ingredients  in  relation  to  the  bulk  or  total 
weight  of  the  article;  and  in  the  case  of  foods  liable  to  decompose,  he 
must  certify  that  no  change  had  taken  place  in  the  constitution  of  the 
article  that  would  interfere  with  the  analysis. 

By  section  14  of  the  1875  Act  and  section  13  of  the  1899  Act,  the  person 
]:)urchasing  for  analysis  must,  after  the  purchase  has  been  completed,  forth- 
with notify  to  the  seller  his  intention  to  have  the  same  analyzed  by  the 
public  analyst,  and  must  divide  the  article  into  three  parts,  to  be  then 
and  there  separated,  and  each  part  to  be  marked,  sealed,  or  fastened  up 
as  its  nature  will  permit,  and  shall,  if  required  to  do  so,  deliver  one  of 
the  })arts  to  the  seller.     One  of  the  parts  is  to  be  retained  for  future  com- 


SANITARY    LAW    AND    ADMINISTRATION  719 

]);ii  isdii,  ;iiul  ])i'()tliicfil  in  court  in  tlic  event  ol  ;i  ])i(iscciiti(ii'.  1  he  tliircl 
part  is  to  be  taken  to  tlii'  public  anahst,  or  scut  to  liini  by  registered 
parcel  post. 

If  llie  offer  to  divide  is  refused,  the  analyst  must  divide  the  sample 
into  two  parts,  and  remit  one  part  to  the  purchaser  for  producti(jn  in  case 
proceedings  sliall  afterwards  be  taken. 

Any  person  refusing  to  sell  to  an  inspector  or  officer  is  liable  to  a  £i<.> 
jienalty. 

All  proceedings  under  these  Acts  must  be  instituted  within  twenty-eight 
days  of  the  date  of  purchase.  The  summons  must  state  tlie  j)articulars  of 
the  offence  alleged,  must  not  be  made  returnable  in  less  time  than  fourteen 
days  from  the  day  on  which  it  is  served  upon  the  defendant,  and  must  be 
served  with  a  copy  of  the  certificate  of  the  public  analyst  obtained  on 
behalf  of  the  prosecutor  (section  ig,  1899  Act).  At  the  hearing  of  the 
summons,  the  certificate  of  the  public  analyst  is  sufficient  evidence  for 
the  prosecution,  unless  the  defendant  requires  him  to  be  called  (section  21, 
1875  Act);  and  on  behalf  of  the  defendant  a  public  analyst's  certificate 
is  sufficient  evidence,  if  a  copy  has  been  sent  to  the  prosecutor  three  clear 
days  before  the  summons  is  heard.  The  justices  may  order  the  sample 
produced  in  court  by  the  prosecutor  to  be  sent  to  the  Commissioners  of 
Inland  Revenue  to  be  analyzed  by  the  chemical  officers  at  Somerset  House, 
and  may  adjourn  the  hearing  to  obtain  the  Somerset  House  certificate 
(section  22,  1875  Act).  They  must  do  so  at  the  request  of  either  party 
(section  21  of  the  1899  Act). 

By  section  25  of  the  1875  Act,  if  the  defendant  prove  that  he  had  pur- 
cliased  the  article  as  the  same  in  nature,  substance,  and  quality  as  that 
demanded  by  the  prosecutor,  and  with  a  written  warranty  to  that  effect, 
that  he  had  no  reason  to  disbelieve  the  warranty,  and  that  he  sold  the 
article  in  the  same  state  as  when  he  purchased  it,  he  is  not  guilty.  By 
section  20  of  the  1899  Act  the  warranty  defence  is  not  available,  unless  a 
copy  of  it  has  been  sent  to  the  prosecutor  within  seven  days  after  the 
service  of  the  summons,  with  the  statement  that  the  warranty  will  be  relied 
on,  and  specifying  the  name  and  address  of  the  person  from  whom  the 
warranty  or  invoice  was  received.  This  person  must  also  be  informed  of 
the  defendant's  intention  to  rely  on  the  warranty,  and  he  is  entitled  to 
give  evidence  at  the  hearing.  Any  person  giving  a  false  warranty  is  liable 
to  heavy  penalties,  unless  he  prove  that  when  he  gave  the  warranty  he 
had  reason  to  believe  that  it  was  true. 

The  system  of  warranties  in  the  milk  trade  of  towns  has  had  the  practical 
effect  of  rendering  the  Acts  valueless.  The  retailer  obtains  his  milk  from 
the  wholesale  dealer  under  a  six  months'  or  one  year's  agreement,  which  is 
a  continuing  warranty  for  the  period  covered;  the  wholesale  dealer  is 
jirotected  by  a  warranty  from  the  farmer.  The  Acts  did  not  contemplate 
the  case  of  successive  warranties,  with  the  result  that  the  farmer's  warranty 
is  held  to  exonerate  the  wholesale  dealer  in  the  case  of  the  latter  being 
prosecuted  for  giving  a  false  warranty  to  the  retail  dealer. 

Milk. — By  section  3  of  the  1879  Act,  an  inspector  may  take  a  sample 
of  milk  for  analysis  which  is  consigned  from  one  person  to  another  in  pur- 
suance of  any  contract.  The  sample  must  be  taken  at  the  place  of  delivery, 
which  in  towns  is  usually  a  railway  station,  where  the  milk  i)asses  into  the 
hands  of  the  consignee  or  his  servants. 

By  section  14  of  the  Sale  of  Food  and  Drugs  Act,  1899,  any  other  article 
of  food  may  be  sampled  in  course  of  delivery  at  the  request  or  with  the 
consent  of  the  consignee. 

By  section  4  of  the  1899  Act  the  Board  of  Agriculture  can  frame  stan- 
dards, for  the  composition  of  genuine  milk,  .including  condensed  milk, 
cream,  butter,  and  cheese,  departures  from  which  standard  raise  a  pre. 


720  HYGIENE    AND   PUBLIC    HEALTH 

sumption,  until  the  contrary  is  proved,  that  the  article  is  adulterated. ^ 
Analysts  must  have  regard  to  these  standards.  Any  person  selling  milk 
or  cream  in  any  street  or  public  place  must  have  conspicuously  inscribed  on 
his  vehicle  or  can  or  churn  his  name  and  address  (section  9).  Every  tin  of 
condensed  "  separated  "  or  "  skimmed  "  milk  must  bear  a  label  clearly 
visible  to  the  purchaser — "  Machine-skimmed  Milk  "  or  "  Skimmed  IMilk  " 
— in  large  and  legible  type.  No  tin  unless  so  labelled  may  be  sold  or 
exposed  or  offered  for  sale. 

The  Public  Health  [Milk  and  Cream)  Regulations,  1912. — These  are 
Regulations  made  by  the  Local  Government  Board  under  the  powers 
conferred  by  the  Public  Health  Act,  1896,  and  the  Public  Health  (Regu- 
lations as  to  Food)  Act,  1907.  In  these  Regulations  the  expression 
"  preservative  substance "  means  any  substance,  preparation,  or 
solution,  which,  when  added  to  milk  or  cream,  is  capable  of  retarding 
the  onset  of  sourness  or  decomposition,  or  is  capable  of  neutralizing 
acidity  (sourness)  in  milk  or  cream.  The  expression  "  thickening  sub- 
stance "  means  sucrate  of  lime,  gelatine,  starch  paste,  or  any  other  sub- 
stance, which,  when  added  to  cream,  is  capable  of  increasing  its  thickness. 
Neither  cane-  nor  beet-sugar  are  to  be  regarded  as  preservatives  or  thicken- 
ing substances.  The  expression  "  milk "  includes  separated,  skimmed, 
condensed,  and  dried  milk;  and  the  expression  "cream"  means  that 
portion  of  milk  rich  in  milk-fat  which  has  risen  to  the  surface  of  milk  on 
standing,  and  has  then  been  removed,  or  which  has  been  separated  from 
milk  by  centrifugal  force.  The  expression  "  preserved  cream  "  means 
cream  containing  35  per  cent,  or  more  by  weight  of  milk-fat  to  which  has 
been  added  boric  acid,  borax,  or  a  mixture  of  these,  or  hydrogen  peroxide. 

Under  the  Regulations  no  person  may  add  any  preservative  substance  to 
milk  intended  for  sale  for  human  consumption,  and  no  person  may  sell, 
or  expose  or  ofier  for  sale,  or  have  in  his  possession  for  the  purpose  of  sale, 
any  milk  to  which  any  preservative  substance  has  been  added.  No  person 
may  add  {a)  any  thickening  substance  to  cream  or  preserved  cream,  or 
ib)  any  preservative  substance  to  cream  containing  less  than  35  per  cent, 
by  weight  of  milk-fat,  or  (c)  any  preservative  substance  to  cream  contain- 
ing 35  per  cent,  or  more  by  weight  of  milk-fat,  other  than  boric  acid,  or 
borax,  or  a  mixture  of  these,  or  hydrogen  peroxide,  in  any  case  in  which 
the  cream  is  intended  for  sale  for  human  consumption.  No  person  may 
sell,  or  expose  or  offer  for  sale,  or  have  in  his  possession  for  the  purpose  of 
sale,  any  cream  to  which  any  thickening  substance  or  any  preservative 
substance  has  been  added,  except  in  so  far  as  above  provided. 

Sellers  of  preserved  cream  must  describe  the  article  as  such  in  their 


1  Under  the  Sale  of  Milk  Regulations,  1901,  of  the  Board  of  Agriculture, 
it  is  provided  that  where  a  sample  of  milk  (not  being  skimmed,  separated, 
or  condensed  milk)  contains  less  than  3  per  cent,  of  milk-fat,  or  less  than 
8*5  per  cent,  of  milk  solids  other  than  milk-fat,  it  shall  be  presumed  for 
the  purposes  of  the  Sale  of  Food  and  Drugs  Acts,  1875  to  1899,  until  the 
contrary  is  proved,  that  the  milk  is  not  genuine,  bj^  reason  of  the  abstrac- 
tion of  milk-fat  or  milk-solids  other  than  milk-fat,  or  the  addition  thereto 
of  water,  as  the  case  may  be.  Under  the  Sale  of  Milk  Regulations,  191 2, 
where  a  sample  of  skimmed  or  separated  milk  contains  less  than  8-7  per 
cent,  of  milk-solids  other  than  milk-fat,  it  shall  also  be  presumed  that  the 
sample  is  not  genuine. 

Under  the  Sale  of  Milk  Regulations,  1902,  the  Board  of  Agriculture  has 
stated  that  where  the  proportion  of  water  in  a  sample  of  butter  exceeds 
16  per  cent,  it  shall  be  presumed  for  the  purposes  of  the  Acts,  until  the 
contrary  is  proved,  that  the  butter  is  not  genuine  by  reason  of  excess  of 
water. 


SANITARY    LAW    AND    ADMINISTRATION  72 1 

advertisements,  price  or  trade  lists ;  and  receptacles  containing  preserved 
cream  intended  for  human  consumption  must  be  labelled  "  Preserved 
Cream  containing  Boric  Acid  not  exceeding  per  cent.,"  or  "  Preserved 

Cream  (Peroxide),"  as  the  case  may  be.  Where  cream  is  consumed  on 
the  premises  of  a  public  restaurant,  the  receptacle  for  preserved  cream 
need  not  be  labelled,  if  a  notice  is  displayed  in  a  conspicuous  position 
in  every  room  in  which  customers  are  served,  that  the  cream  sujiplied  is 
"  preserved  cream,"  or  if  by  some  other  adequate  means  similar  intimation 
is  publicly  given. 

The  Regulations  are  to  be  enforced  and  executed  by  local  sanitary 
authorities;  but  before  proceedings  are  instituted  against  any  person  for 
contravention,  opportunity  must  be  afforded  him  of  furnishing  an  ex- 
planation in  writing  or  otherwise,  as  the  local  authority  may  appoint, 
and  the  local  authority  shall  duly  consider  any  such  explanation  and 
all  the  circumstances  of  the  case.  Samples  may  be  taken  by  the  olTicers 
named  in  section  13  of  the  Sale  of  Food  and  Drugs  Act,  1875,  in  accordance 
with  the  provisions  of  section  14  of  the  Act. 

The  Regulations  also  prohibit  the  importation  into  England  and  Wales 
of  any  foreign  milk  or  foreign  cream  not  in  accordance  with  the  pro- 
visions of  the  Regulations  already  referred  to. 

The  penalt)'  for  a  contravention  of  the  Regulations  is  a  fine  not  exceeding 
£100,  and,  in  the  case  of  a  continuing  offence,  a  further  penalty  not  exceed- 
ing 5^50  for  every  day  during  which  the  offence  continues  (Public  Health 
Act,  ^  896). 

Butter  and  Margarine.  —  By  the  Margarine  Act,  1887,  butter  is 
defined  as  made  exclusively  from  milk  or  cream,  or  both,  with  or  without 
salt  or  other  preservative,  and  with  or  without  added  colouring  matter. 
Margarine  includes  all  substances,  whether  compounds  or  otherwise, 
prepared  in  imitation  of  butter,  and  whether  mixed  with  butter  or  not. 
Every  package  of  margarine  must  be  so  marked  in  printed  capital  letters 
not  less  than  J  inch  square;  if  exposed  for  sale  by  retail,  the  label  must 
be  printed  "  Margarine  "  in  letters  U  inches  square.  When  margarine  is 
sold  retail,  it  must  be  delivered  to  the  purchaser  in  a  paper  wrapper  on 
which  "  Margarine  "  is  printed  in  capital  block  letters  not  less  than  4  inch 
long  and  distinctly  legible,  and  no  other  printed  matter  must  appear  on 
the  wrapper  (Sale  of  Food  and  Drugs  Act,  1899,  section  6).  An  officer 
taking  samples  under  this  Act  is  not  required  to  go  through  the  form  of 
purchase,  but  otherwise  the  procedure  is  the  same  as  under  the  Sale  of 
Food  and  Drugs  Acts.  Any  substance  not  marked  as  margarine  is  pre- 
sumed to  be  exposed  for  sale  as  butter.  By  the  Sale  of  Food  and  Drugs 
Act,  1899,  "Margarine"  and  "Margarine-cheese"  must  be  branded  on 
the  package  itself,  and  not  solely  on  an  attached  label  or  ticket,  in  capital 
block  letters  1  inch  long.  By  this  Act  also  margarine-cheese  is  included 
in  all  provisions  relating  to  margarine,  and  the  same  measures  must  be 
taken  to  differentiate  margarine-cheese  and  cheese  as  are  necessary  to 
differentiate  margarine  and  butter.  Manufactories  of  margarine  and  of 
margarine-cheese  must  be  registered  with  the  local  authorities  of  the  district 
in  which  they  are  situate,  and  notice  of  registration  must  be  sent  to  the 
Board  of  Agriculture.  No  margarine  imported,  manufactured,  or  sold 
may  contain  more  than  10  per  cent,  of  butter  fat  (Sale  of  Food  and  Drugs 
Act,  1899,  section  8). 

The  Butter  and  Margarine  Act,  1907. — By  this  Act,  which  came  into 
force  on  January  i,  1908,  a  statutory  maximum  limit  of  i6per  cent,  of  water 
is  imposed  in  the  case  of  all  butters,  with  the  exception  of  "  milk-blended 
butter,"  which  is  to  be  allowed  to  have  as  much  as  24  per  cent.,  so  long  as 
it  is  sold  by  a  name  which  is  approved  by  the  Board  of  Agriculture  and 
one  which  is  not  "  suggestive  of  butter  or  anything  connected  with  the 

46 


722  HYGIENE    AND    PUBLIC    HEALTH 

dairy  interest."  The  names  under  which  margarine  is  sold  are  to  be  sub- 
ject to  the  same  restrictions.  The  principal  advantage  of  the  Act  is  the 
substitution  of  a  system  of  control  at  the  port  of  importation  (through 
the  Customs  authorities  and  the  Government  laboratory),  and  in  this 
country  .at  the  place  of  manufacture,  for  the  present  methods,  which  are 
based  almost  wholly  on  analysis  of  purchased  samples.  Places  where 
butter  is  blended  "  by  way  of  trade  "  will  now  have  to  be  registered,  and 
no  foreign  fats  are  to  be  kept  on  such  premises.  Wholesale  "  blending  " 
of  butter  and  margarine  making  are  not  to  be  carried  out  on  the  same 
premises,  although  exceptions  may  be  made  for  existing  factories.  Another 
considerable  advantage  of  the  Act  is  that  it  empowers  the  Local  Govern- 
ment Board  to  schediile  and  to  regulate  the  use  of  preservatives  in  butter, 
milk-blended  butter  and  margarine,  and  it  may  be  hoped  that  this  will 
speedily  be  done.  A  circular  has  been  issued  by  the  Board  of  Agriculture 
as  to  the  action  which  local  authorities  are  recommended  to  take  under 
the  new  Act.  Apparently  the  principal  duty  required  of  them  is  to  see 
that  butter-blending,  milk-blending,  and  margarine-making  premises  are 
all  duly  registered,  and  to  report  to  the  Board  of  Agricultvire  cases  where 
in  course  of  ordinary  sampling  it  is  found  that  the  permitted  limits  of 
moisture  have  been  exceeded.  It  may  be  gathered  from  the  circular  that 
routine  inspection  of  the  registered  factories  will  be  made  by  officers  of  the 
Board  of  Agriculture.  The  circular  points  out,  however,  that  under 
section  2  of  the  new  Act  local  authorities  have  power  to  authorize  any 
officer  who  is  authorized  to  procure  samples  under  the  Sale  of  Food  and 
Drugs  Act  to  enter  any  registered  butter  factory  for  the  purpose  of 
inspection  of  processes  and  of  taking  samples. 

Spirits. — By  section  6  of  the  Sale  of  Food  and  Drugs  Act  Amendment 
Act,  1879,  brandy,  whisky,  and  rum  may  be  sold  25  degrees  under  proof 
and  gin  35  degrees  under  proof.  Spirits  may  be  sold  diluted  to  a  greater 
extent,  if  a  customer's  attention  is  called  to  the  fact  of  greater  dilution 
being  practised  in  the  establishment  in  which  he  is  being  served,  but  not 
otherwise. 

The  chief  provisions  of  the  Sale  of  Food  and  Drugs  Act,  1899,  have 
been  alluded  to  above.  In  addition,  it  may  be  noted  that  importers  of 
margarine,  margarine-cheese,  skimmed  or  separated  condensed  milk,  and  of 
other  adulterated  or  inipoverished  articles  of  food,  unless  such  articles  are 
conspicuously  labelled  or  described,  are  liable  to  a  penalty.  The  Local 
Governm.ent  Board  and  the  Board  of  Agriculture  may  direct  their  officers  to 
procure  for  analysis  any  article  of  food  in  any  district.  Such  officer  divides 
his  sample  into  four  parts,  sending  one  part  to  his  board  and  one  to  the 
public  analyst  of  the  district,  whose  fee  is  payable  by  the  local  authority 
of  the  district.  If  the  sample  is  adulterated,  the  analyst's  certificate  is 
to  be  sent  to  the  local  authority,  who  are  required  to  prosecute.  By  this 
Act  also  every  local  authority  is  now  required  to  appoint  a  public  analyst 
and  to  administer  the  Acts.  In  case  of  failure  to  do  so,  either  the  Local 
Government  Board  or  the  Board  of  Agriculture  may  empower  an  officer 
to  execute  and  enforce  the  provisions  of  the  Acts,  and  the  expenses  so 
incurred  must  be  paid  by  the  local  authority  to  the  Board  on  demand. 
Public  analysts  to  be  ap})ointed  must  furnish  such  proof  of  competency 
as  the  regulations  of  the  Local  Government  Board  may  require. 

The  Tuberculosis  Order  of  1913. 

This  Order,  which  has  been  issued  by  tlie  Board  of  Agriculture  and 
Fisheries,  came  into  operation  on  May  i,  191 3.  It  is  an  Order  issued  in 
the  interests  of  the  public  health  as  well  as  of  agriculture,  for  the  relation 
between  tuberculosis  in  human  beings  and  in  animals  has  been  the  subject 


SANITARY    LAW   AND    ADMINISTRATION  723 

of  careful  investigation  by  several  Royal  Commissions,  and  it  is  now 
accepted  as  a  fact  that  this  disease  is  transmissible  by  the  agency  of  milk 
used  for  human  consumption. 

This  Order  aims,  therefore,  at  securing  the  destruction  of  every  cow 
foimd  to  be  sufEering  from  tuberculosis  of  the  udder  or  to  be  giving  tuber- 
culous milk,  as  well  as  of  all  bovine  animals  which  are  suffering  from 
tuberculosis  with  emaciation,  since  these  are  known  to  disseminate  freely 
the  germs  of  the  disease.  Local  autliorities  are  required,  with  all  prac- 
ticable speed,  to  investigate  reports  received  under  the  Order  or  otherwise, 
with  the  assistance  of  a  veterinary  surgeon,  with  a  view  to  causing  the 
slaughter  of  any  animal  in  their  district  shown  to  be  sufEering  from  either 
of  these  specified  forms  of  tuberculosis. 

The  Order  gives  power  to  the  veterinary  inspector  to  examine  anj' 
bovine  animals  upon  premises  that  have  been  associated  with  a  sus- 
pected animal,  and  for  the  purpose  of  diagnosis  he  may  apply  the  tuber- 
culin test,  with  the  written  consent  of  the  owner  of  the  suspected  animal, 
but  not  otherwise.  He  may  also  take  samples  of  milk,  fa'ces,  urine,  and 
abnormal  discharges  for  bacteriological  examination. 

The  Order  requires  every  person  having  in  his  possession  any  cow  which 
appears  to  be  sufiering  from  tuberculosis  or  other  disease  of  the  udder,  or 
any  bovine  animal  suspected  to  be  sufiering  from  tuberculosis,  to  notify 
the  fact  to  a  police  constable  or  to  an  inspector  of  the  local  authority. 
A  veterinary  surgeon  is  required  to  notify  in  a  similar  way  any  such  case 
in  connection  with  his  private  practice. 

The  local  authority  are  required  by  Article  5  of  the  Order  to  cause  every 
animal  found  by  them  to  be  suffering  from  one  of  the  specified  forms  of 
tuberculosis  to  be  slaughtered.  The  animal  to  be  slaughtered  is  to  be 
valued  in  its  condition  at  the  time  of  valuation.  Inasmuch,  however,  as 
the  clinical  diagnosis  made  by  the  veterinary  inspector  prior  to  slaughter 
may  not  be  confirmed  on  post-mortem  examination,  it  is  provided  in 
paragraph  (3)  of  Article  6  of  the  Order  that  there  shall  be  separate  valua- 
tions on  the  basis  both  of  the  animal  proving  to  be  afiected  with  tuber- 
culosis and  of  its  proving  to  be  not  so  afiected,  and  the  amount  of  the  com- 
pensation will  depend  on  the  result  of  the  examination. 

The  compensation  payable  by  the  local  authority  for  an  animal 
slaughtered  under  their  direction  in  cases  in  which  the  post-mortem  ex- 
amination does  not  show  tuberculosis  is  a  sum  equal  to  the  full  value  of 
the  animal  and  a  further  sum  of  twenty  shillings. 

Where  tuberculosis  is  found,  the  proportion  of  the  value  of  the 
animal  payable  by  way  of  compensation  to  the  owner  is  made  to  depend 
upon  the  extent  of  the  disease  which  is  present.  The  Board  have 
adopted  the  classification  of  the  Royal  Commission  as  a  basis  on  which 
the  proportion  of  compensation  payable  under  their  Order  is  to  be 
determined. 

The  degrees  of  tuberculosis  described  in  Article  8  (4)  of  the  Order  are 
those  which  indicate  a  generalized  infection  of  the  carcass.  WTierever 
such  conditions  are  certified  to  exist,  the  compensation  is  fixed  at  a  sum 
equal  to  one-fourth  of  the  value  of  the  animal  valued  as  a  tuberculous 
animal,  or  the  sum  of  thirty  shillings,  whichever  sum  is  greater,  after 
deducting  from  such  sum  one-half  of  the  costs  incurred  by  the  local 
authority  for  any  valuation  of  the  animal  by  a  valuer  appointed  by  the 
Board,  or  for  any  examination  of  its  carcass  by  a  veterinary  surgeon  other 
than  the  veterinary  inspector.  For  convenience,  these  conditions  are 
described  in  the  Order  as  "  advanced  tuberculosis."  In  all  other  cases 
of  tuberculosis — i.e.,  in  cases  where  a  carcass,  if  otherwise  healthy,  need 
not  in  the  opinion  of  the  Commissioners  be  condemned  as  imfit  for  food 
except  as  regards  the  portions  containing  tuberculous  lesions,  the  com- 


724  HYGIENE    AND   PUBLIC   HEALTH 

pensation  is  to  be  a  sum  equal  to  three-fourths  of  the  value  of  the  animal, 
after  deducting  from  such  sum  one-half  of  the  costs  of  valuation  and  ex- 
amination as  in  the  preceding  case. 

The  Order  prescribes  the  precautions  to  be  taken  in  respect  of  the  milk, 
etc.,  of  suspected  animals  (Article  9),  and  their  detention  and  isolation 
whilst  under  suspicion  (Article  10).  Provision  is  also  made  in  Article  11 
of  the  Order  for  dealing  with  suspicious  animals  exposed  at  markets, 
fairs,  or  sales. 

The  Board  of  Agriculture  have  obtained  authority  from  the  Treasury 
to  refund  to  local  authorities  from  monies  provided  by  Parliament  one- 
half  of  the  net  amount  payable  by  way  of  compensation  for  slaughtered 
animals  during  a  period  of  five  years  from  the  coming  into  operation  of 
the  Order.  Local  authorities  will  thus  receive  substantial  pecuniary 
relief  during  the  initial  stages  of  the  operations  now  to  be  undertaken, 
during  which  the  expenditure  involved  in  the  administration  of  the  Order 
may  be  expected  to  be  abnormally  high. 

The  Board  state  that,  although  it  is  inevitable  that  at  the  outset  of  the 
operations  the  expenditure  should  be  comparatively  heavy,  inasmuch  as 
the  first  effects  of  the  Order  will  be  to  bring  within  its  purview  the  cows 
of  all  ages  suffering  from  tuberculosis  of  the  udder  or  giving  tuberculous 
milk, and  bovine  animals  of  all  kinds  which  show  signs  of  tuberculosis 
with  emaciation,  it  is  anticipated  that  when  the  Order  has  been  in  opera 
tion  for  a  few  years  those  animals  only  will  fall  to  be  dealt  with  which  from 
an  outwardly  healthy  condition  develop  these  forms  of  the  disease.  The 
cost  to  the  local  authority  of  the  administration  of  the  Order  after  the 
initial  period  has  elapsed  should  not  be  great,  and  may  properly  be  de- 
frayed in  full  by  local  authorities  in  the  manner  provided  for  in  the  Diseases 
of  Animals  Acts. 

It  is  abundantly  clear,  the  Board  says,  that  any  operations  aiming  at 
the  diminution  or  eradication  of  tuberculosis  in  animals  must  be  com- 
menced with  caution,  and  carried  out  with  due  regard  to  the  extent  to 
which  the  disease  is  believed  to  exist  amongst  cows,  and  to  the  importance 
of  securing  the  continuance  of  an  adequate  milk  supply,  and  of  avoiding 
any  disorganization  of  the  important  industry  concerned. 


THE   DUTIES   OF  A   MEDICAL   OFFICER  OF  HEALTH. 

Extract  from  the  General  Order  of  the  Local  Government  Board 
(December  13,  1910). 

Article  XIX. — The  following  shall  be  the  duties  of  the  medical  officer 
of  health  in  respect  of  the  district  for  which  he  is  appointed;  or  if  he  is 
appointed  for  more  than  one  district,  then  in  respect  of  each  district: 

(14)  He  shall  as  soon  as  practicable  after  December  31  in  each  year 
make  an  annual  report  to  the  Council,  up  to  the  end  of 
December,  on  the  sanitary  circumstances,  the  sanitary  ad- 
ministration, and  the  vital  statistics  of  the  district. 

In  addition  to  any  other  matters  upon  which  he  may  con- 
sider it  desirable  to  report,  his  annual  report  shall  contain 
the  information  indicated  in  the  following  paragraphs;  to- 
getlier  with  such  further  information  as  we  may  from  time  to 
time  require: 

(a)  An  account  of  any  influences  threatening  the  health 
of  the  district,  the  prevalence  of  infectious  or  epidemic 
diseases  therein,  and  the  measures  taken  for  their  preven- 
tion. 


SANITARY   LAW    AND    ADMINISTRATION  7^5 

{b)   An   account   of   all  general   and   special   inquiries   made 

^tr^N^'aSnt  of  the  work  performed  by  the  inspector  of 
nuisances  during  the  year,  including  tl>e  statement  supplied 
in  pursuance  of  Article  XX.  (i6)  of  this  Order 

id)  A  statement  as  to  the  conditions  affecting  the  wholc- 
someness  of  the  milk  produced  or  sold  in  the  ^l\^tnct 

(e)   A  statement  as  to  the  conditions  affecting  the  who  c 
someness  of  foods  for  human  consumption,  other  than  nnlk, 
produced  or  sold  in  the  district.  i;+„  m  the 

if)  A  statement  as  to  the  suUiciency  and  quality  of  the 
water-supply  of  the  district  and  of  its  several  parts,  and  in 
rr'as\rere'the  supply  is  from  waterworks,  information  as  to 
whether  the  supply  is  constant  or  intermittent. 

te)   A  stoternVnt  as  to  the  p<.llution  of  rivers  or  streams  in 

*^'*(/rA  Statement  as  to  the  character  and  sull.ciency  of  the 
arrangements  for  the  drainage,  sewerage,  and  sewage  disposal 
in  all  parts  of  the  district. 

(0  A  statement  as  to  the  privy,  water-c  oset.  and  other 
closet  accommodation  in  the  district,  including  information 
as  to  the  approximate  number  of  each  type  of  privy  and  c  -e  . 
(/)  A  statement  as  to  the  character  and  elftciency  of  the  ar- 
rangements for  the  removal  of  house-refuse,  and  t-  clean  in, 
of  earth-closets,  privies,  ashpits,  and  cesspools  in  the  ^i^tnct 

"k)  A  statement  with  regard  to  the  ^"--8,^^^°"^"^'^;^"  ^^^ 
of  the  district  as  required  by  Article  V.  of  the  Housing  (In- 
spection of  District)  Regulations  1910.  and  an  account  cf 
any  other  action  taken  by  the  Councd  under  the  Housing. 
Town  Planning,  etc..  Act.  1909.  bearing  on  tl-  l-^^^^f  ^^. 
(/)  A  statement  as  to  the  vital  statistics  of  the  district  m 
cludin"  a  tabular  statement,  in  such  form  as  we  may  from  time 
?o  time  direct,  of  the  sickness  and  mortality  within  the  district. 
M  Where  the  Medical  Officer  of  Health  ^^^  appoin  ed  by 
the  Council  of  a  county  borough,  or  by  a  C°unci  having 
delegated  powers  under  the  Midwives  Act.  190^,  a  statement 
as  to  the  administration  of  that  Act  in  the  district : 

Provided  that,  if  the  Medical  Officer  of  Health  sha  1  resign 
or  be  removed  before  December  31  m  any  year  he  shall 
as  soon  aT  practicable  after  going  out  of  office  make  o  the 
CouncU  the'^like  report  for  so  much  of  the  year  as  shall  have 
expired  when  he  ceased  to  hold  office. 
*  *  *  * 

(16)  He  shall  transmit  to  us  three  copies  of  each  annual  report  and 
one  copv  of  any  special  report.  At  the  same  time  that  he 
?rTnS  to  us  t'he'copies  of  his  annual  report  or  of  any  specia 
rpnort  or  that  he  reports  to  us  a  case  of  plague,  cholera  or 
lZn%oVheLll  transmit  a  copy  of  the  report  or  give  the 
iSe  information  to  the  County  Council  or  County  Councils 
of  the  county  or  counties  within  which  the  district  is  situated. 
Where  the  Medical  Officer  of  Health  is  appomted  by  the 
Comrcil  of  a  county  borough,  or  by  a  Counci  ^-ving  delegat  d 
uowcrs  under  the  Midwives  Act,  1902,  he  shall  also  transmit 
to  the  P  vy  Council  and  to  the  Central  Midwives  Board  either 
a  copy  of  his  annual  report  or  of  that  part  of  it  which  contains 
the  Satement  relating  to  the  administration  of  the  Midwives 
Act,  1902. 


726  HYGIENE    AND    PUBLIC   HEALTH 


Extract    i-rom    the    Housing  (Inspection    of  District)  Regulations, 
1 9 10   (September  2). 

Article  V. — -The  Medical  Officer  of  Health  shall  include  in  his  annual 
report  information  and  particulars  in  tabular  form  in  regard  to — 

The  number  of  dwelling-houses  inspected  under  and  for  the  purposes 

of  Section  17  of  the  Act  of  1909; 
The  nunaber  of  dwelling-houses  which  on  inspection  were  considered 

to  be  in  a  state  so  dangerous  or  injurious  to  health  as  to  be  unfit 

for  human  habitation ; 
The  number  of  representations  made  to  the  local  authority  with  a 

view  to  the  making  of  closing  orders ; 
The  number  of  closing  orders  made; 
The  number  of  dwelling-houses  the  defects  in  which  were  remedied 

without  the  making  of  closing  orders ; 
The  number  of  dwelling-houses  which  after  the  making  of  closing 

orders  were  put  into  a  fit  state  for  human  habitation ;  and 
The  general  character  of  the  defects  found  to  exist. 

He  shall  also  include  any  other  information  and  particulars  which  he 
may  consider  desirable  in  regard  to  the  work  of  inspection  under  the  said 
section. 

Extract  from  the  Factory  and  Workshop  Act,   1901. 
Section  132  of  the  above  Act  requires  that — 

The  Medical  Officer  of  Health  of  every  District  Council  shall,  in  his 
annual  report  to  them,  report  specifically  on  the  administration  of  this 
Act  in  workshops  and  work-places,  and  he  shall  send  a  copy  of  his  annual 
report,  or  so  much  of  it  as  deals  with  this  subject,  to  the  Secretary  of 
State. 


County  Councils  as  Sanitary  Authorities. 

County  Councils  were  created  by  the  Local  Government  Act  of  1888, 
but  this  Act  gave  them  little  power  in  sanitary  matters.  County  Councils 
were  empowered  by  that  Act  to  appoint  a  County  Medical  Officer  of 
Health;  they  were  given  powers  of  enforcing  the  provisions  of  the  Rivers 
Pollution  Prevention  Act,  1876,  and  (by  the  amending  Act  of  1893)  even 
against  sanitary  authorities  discharging  sewage  into  streams;  the  Councils 
were  also  given  power  to  make  by-laws  for  the  good  rule  and  government 
of  the  county  and  for  preventing  and  suppressing  nuisances  not  already 
punishable  in  a  summary  manner;  the  duty  of  appointing  public  analysts 
and  putting  in  xorce  the  provisions  of  the  Food  and  Drugs  Acts  was  im- 
posed upon  County  Councils,  in  all  cases  except  for  boroughs  having  a 
population  of  10,000  or  more;  every  District  Medical  Officer  of  Health  was 
required  to  send  a  copy  of  his  annual  or  special  reports  to  the  County 
Council;  and  the  County  Council  could  make  "representations"  to  the 
Local  Government  Board  in  respect  to  defaulting  sanitary  authorities 
within  its  area.  This  was  the  first  provision  conferring  upon  them  super- 
visory powers  upon  matters  affecting  the  public  health.  Later,  under  the 
Housing  of  the  Working  Classes  Act.  1890,  rural  sanitary  authorities 
were  required  to  send  to  the  County  Council  a  copy  of  any  representation, 
complaint,  or  information  made  to  them,  and  also  copies  of  closmg  orders; 
and  if  the  County  Council  finds  a  rural  sanitary  authority  in  default  it 
is  empowered  to  take  over  the  duties  of  the  rural  sanitary  authority.      In 


SANITARY   LAW    AND   ADMINISTRATION  72^ 

the  year  1893  the  Isolation  Hospitals  Act  gave  County  Councils  C(jnsider- 
able  powers  for  establishing  fever  hospitals.  Under  the  Local  Government 
Act  of  1894  a  Parish  Council  may  com])lain  to  the  County  Council  when  a 
Rural  District  Council  fails  to  provide  suOicient  sewers  or  a  sufficient 
and  wholesome  water-supply,  and  the  County  Council  may  by  resolution 
take  over  the  duties  of  any  such  Rural  District  Council.  Under  the 
Hcnising  and  Town  f'lanning  Act  of  1909  there  is  an  alternative  form 
of  procedure  given  in  respect  to  defaulting  Rural  or  Urban  District 
Councils  in  dealing  with  unhealthy  dwellings;  for  the  County  Council 
may  either  take  over  the  powers  of  the  defaulting  authority  or  complain 
to  the  Local  Government  Board.  A  similar  complaint  may  be  made  to 
the  Local  Government  Board  in  case  of  alleged  default  by  the  district 
authority  in  the  supply  of  workmen's  dwellings  under  Part  3  of  the  Act 
of  1890. 

The  Midwives  Act  of  1902  imposed  a  new  duty  upon  County  Councils 
by  constituting  them  the  "  local  supervising  authority  "  over  the  midwives 
within  their  area.  The  Notitication  of  Births  Act,  1907,  may  be  adopted 
by  County  Councils,  and  at  the  time  of  writing  (August.  191 3)  has  been  so 
adopted  by  three  of  them.  Under  the  Education  (Administrative  Pro- 
visions) Act,  1907,  which  provides  for  the  medical  inspection  of  school 
children,  County  Councils  (as  education  authorities)  are  doing  valuable 
work;  and  under  Section  122  of  the  Children  Act,  1908,  they,  as  the  educa- 
tion authority,  have  powers  for  the  cleansing  of  verminous  children,  and 
for  taking  the  necessary  proceedings  to  compel  the  parent  to  keep  the 
child  clean. 

The  duties  of  the  County  Medical  Officer  of  Health  consist  in  advising 
the  County  Council  in  the  administration  of  the  above-mentioned  Acts, 
and  generally  upon  all  matters  of  public  health  importance  coming  within 
their  jurisdiction.  As  the  officer  of  a  supervising  authority  he  keeps  in 
close  touch  with  the  work  of  the  District  Medical  Officers  of  Health,  and 
consults  and  confers  with  them.  For  each  year  a  report  has  to  be  com- 
piled dealing  generally  with  the  sanitary  circumstances  of  the  county  and 
summarizing  the  facts  contained  in  the  annual  reports  of  the  District 
Medical  Officers  of  Health.  In  conclusion,  mention  may  be  made  of  the 
fact  that  the  work  of  County  Councils  embraces  many  matters  which  have 
no  public  health  bearing ;  they  are,  for  instance,  the  local  authorities  which 
deal  with  highways  and  bridges,  the  police,  weights  and  measures,  places 
of  public  amusement,  lunatic  asylums,  fisheries,  explosives,  etc. 


INDEX 


Abattoirs,  public,  351 

"ABC"  process,  140 

Acetylene,  259 

Actinomycosis,  338,  533 

Adulteration  of  food  and  drugs, 
404,  717 

Aerial  spread  of  small-pox,  429 

"  After-flush  "  for  valve  w.c,  93 

Age  and  sex  distribution,  640 

Agglutination  tests,  420,  471 

Agglutinins,  420 

Ague  {see  Malaria) 

Air,  167 

Albo-carbon  light,  259 

Albuminoids,  313 

Alcohol,  effects  of,  395 

Aliens  Act,  667 

Alkali  works,  194,  717 

Alkaloids,  poisonous,  in  sewer  air, 
181;  in  the  body,  316;  in  meat, 
345 ;  produced  by  specific  mi- 
crobes, 416 

Alum,  for  purifying  water,  Ou;  in 
breaa,  385 

Alumina,  sulphate  of,  as  a  sewage 
precipitant,   137 

Amalgaline  joints,  102 

Amboceptors,  421 

Amines  process,  138 

Ammonia  in  water,  69 

Amceba  coli,  507 

Anaphylaxis,  425 

Anderson's  process  of  water  filtra- 
tion, 53 

Anemometers,  239 

— Robinson's  wind,  291 

Aneroid  barometer,  290 

Angus  Smith's  solution,  41 

Aniline  dyes,  310,  398 

Animal  charcoal  for  filters,  60 

Ankylostomiasis,  120,  524 

Anopheles,  514 

Anthrax,  412,  525 

Anti-cyclonic  system,  286 

Anti-D  trap,  95 

Antigen,  422 

Antiseptics,  598;  in  milk,  363 

Antitoxins,  423,  461 

Anti-typhoid  inoculations,  472 

Aqueducts,  1,41 


Areas,     "open"    and     "dry"    for 

houses,  270 
Argand  burner,  258 
Amott's  valve,  225 
Arrowroot,  387 
Arsenic    in    wall    papers,    2u6;    in 

beer,  394 
Arsenical  poisoning,  206,  202,  394 
Artesian  wells,  31 
Artificial  illumination,  257 
— manure  factories,  199 
Ash-closets,  81 

Aspiration,  ventilation  by,  207,  219 
Atmometers,  295 
Atmospheric  electricity,  301 
— pressure,       increase      of,      279  ; 

diminution  of,  278 
Attenuation  of  vira,  417 
Autoclave,  614 
Averages,  632 

Back-to-back  houses,  209,  481 

Bacteria  in  rain,  4;  in  drinking 
water,  69;  in  the  soil,  160;  in 
sewer  air,  181  ;  of  intestinal  type, 
12,  15,  70;  in  digestion,  315 

Bacterial  sewage  filters,  146 

Bacteriolysins,  421 

Bakehouses,  716 

Baking  powders,  382 

Balance  svstem  ot  ventilation.  2t,^ 

Barley,  386 

Barograph,  299 

Barometer,  2 87 

Bath  heaters,  247 

Beans,  387 

Beer,  393 

Beri-beri,  520 

Berkefeld  filter,  62 

Bilharzia  hegmatobia,  341 

Biological  examination  of  water,  O9 ; 
purification  of  sewage,  142 

Birth  rate,  639 

Blackwater  fever,  5 1 7 

Blood -boiling,  195 

Boilers,  5,  256 

Bond's  stove,  248 

Bone-boiling,  196 

Bones,  nourishment  in,  nz 

Books,  disinfection  of,  624 


728 


INDEX 


729 


Boots,  312 

Botliyit)ccphalus  latiis,  334 
Boyle's  valve,  225 
Brain  fatif,uie,  568 
Branch  il rains,  107 
Brandy,  392 

Brass  founder's  ague,  192 
Bread,  382 

Brewery  waste  in  sewage,  152 
Brick  burning,  194 
Bricks,  capacity  for  liokling  mois- 
ture, 269 
Budde  process,  365 
Burial  628 
— grounds,  628,  697 
Burners,  gas,  258 
Butter,  377,  721 
By-laws,  669 

Caisson  disease,  280 

Calf -lymph,  439 

Calories,  324 

Canal  boats,  71 1 

Cancer,  498 

Candles,  261 

Candy's  sprinkler,  154 

Canned  foods,  399 

Carbo-hydrates,  318 

Carbolic  acid,  6iu 

Carbon  block  filters,  61 

— in  diets,  313 

Carbonic  acid,  in  outer  air,  167; 
in  expired  air,  169;  in  crowded 
rooms,  170;  from  combustion  of 
gas,  178;  in  wells,  203 

Carbonic  oxid<",  179,  203,  246 

Carriers,  461,  463,  496 

Catchment  basin,  7 

Cattle,  fever  in,  527 

— tuberculosis  in,  531 

Cellar  dwellings,  682 

Cemeteries,  628,  697 

Cerebro-spinal  fever,  494 

Cesspools,  24,  79;  emptied  by  pneu- 
matic pressure,  80;  fatal  results 
from  opening,  183 

Chalk  fissures,  163 

— soils,  29,  268;  borings,  30 

Channel  pipes,  107 

Charcoal,  wood,  in  sewer  ventila- 
tors, 129 

Cheese,  378,  721 

Chicken-pox,  453 

Chicory,  388 

Chiklhood,  clothing  in,  310 

Children  Act,  the,  71)0 

Chimneys,  use  of,  in  ventilation, 
220 

Chinosol,  61  3 

Chittenden's  experiments,  325 

Chloride  of  lime,  612 

Chloride  of  zinc,  613 


Chlorination  of  water,  53 

Chlorine  as  a  disinfectant,  012,  OiH 

Cholera,  503;  from  polluted  water, 
17.  65 

Cholera  orders,  605 

Chromium  poisoning,  202 

Cisterns,  45 

Clark's  ]>rocess,  51 

Classification  of  causes  of  deaths, 
660 

Clay,  London,  29 

Cleansing  of  I'ersons  Act,  O98 

Climate,  276 

Clothing,  306 

Clouds,  297 

Coal,  177;  combustion  of,  177 

— dust,  190 

Coal  gas,  177;  combustion  of,  178; 
escapes  of,  180 ;  illumination,  257  ; 
manufacture  of,  178;  purification 
of,  178 

— miners,  189 

Cocoa,  390 

Coffee,  388 

Coke  for  filters,  i  5 1 

Cold,  effects  of,  on  body,  276 

Colza  oil,  261 

Common  lodging-houses,  683 

Conrmunicable  diseases,  408;  mi- 
crobial origin  of,  409 

Complement,  421 

Condensed  milks,  361 

Confectionery,  colouring  matters  of, 
398 

Conservancy  systems,  78 

Contacts,  461,  463,  495,  496 

Contagia,  the,  408 

Contagious  Diseases  Acts,  502 

Convection,  heating  by,  247 

Cooking,  342 

Cooper's  ventilator,  zzt, 

Copper  poisoning,  192 

Correlation,  634 

Cotton,  306 

— factories,  715 

County  Councils  as  Sanitary-  Au- 
thorities, 726 

Cowls  for  chimney  tops,  220 

Cow-pox,  416,  441 

Cow's  milk,  358 

Cream,  365,  720 

Creches,  331 

Cremation,  627,  698 

— of  house  refuse,  74 

— of  organic  vapours,  197 

Crops  of  sewage  farms,  104 

Cubic  space  in  inhabited  rooms, 
216;  in  hospitals,  549;  estima- 
tion of,  239 

Curd  of  human  and  cow's  milk,  356 

Customs  and  Inland  Revenue  Act, 
710 


730 


HYGIENE    AND   PUBLIC    HEALTH 


Cyclonic  systems,  283 
Cysticerci,  333 

Dairies,  cowsheds,  and  milkshops, 
689 

Damp-proof  course,  270 

D an jf'sz  bacillus,  512 

Daylight  illumination,  559 

Deacon's  waste-water  meter,  42 

Dead,  disposal  of,  627,  697 

Death  certificates,  660 

Death  rates,  638;  calculation  of, 
639;  significance  of,  640;  rural 
and  urban,  643,  649;  in  relation 
to  density  of  population,  644; 
correction  of,  for  age  distribu- 
tion, 642;  standard,  642;  in- 
fluence of  birth  rate  upon,  647 ; 
of  combined  districts,  639;  at 
special  age  periods,  640;  of 
special  diseases,  645;  fallacies  in 
connection  with,  660 

Deaths,  in  public  institutions,  639 

Dengue,  522 

Deodorants,  598 

Destructor  furnace,  74 

Dew  point,  294 

Diarrhoea,  64,  473 ;  from  meat 
poisoning,  345 

Dibdin's  experiments,  146 

Diets,  321 ;  training,  305 

Diffusion  of  gases,  207 

Digestibility  of  food,  321 

Digestive  processes,  the  influence 
of  bacteria  on,  315 

Diphtheria,  414,  455;  from  milk, 
370 

Disconnection  of  house  drain,  107 

Disinfectants,  liquid,  609;  gaseous, 
614;  solid,  620;  standardizing  of, 
599 

Disinfecting  station.  607 

Disinfection,  598;  by  boihng  water, 
602;  by  burning,  601;  by  dry 
heat,  602  ;  by  steam,  603  ;  of  sick- 
room by  sprays  and  gaseous  air 
purifiers,  621 ;  of  stools  and  sputa 
by  liquid  reagents,  624;  of  ships, 
625 

Disinfcctors,  steam,  603 

Distillation  of  water,  58 

Distributors,  sewage,  154 

Distoma  hepaticum,  339 

Domestic  drj?^  refuse,  removal  of, 
72i  \  disposal  of,  73 

Dortmund  tank,  138 

Drain  sewers,  88,  121 

Drains,  house,  104;  testing  of,  115; 
law  as  to,  671 

Drying  power  of  air,  294 

Ducat's  system,  149 

Durax  paving,  272 


Dust,  in  air,  187;  from  traile  pro- 
cesses, 190,  232;  household,  72, 
204 

Dustbins,  -jt, 

Dwelhngs,  movable,  71U 

Dynamite,  229 

Dysentery,  65,  506 

Karth  system,  Moule's  dry,  83 

— temperatures  in  relation  to  diar- 
rhoea, 475 

Education  Code,  591 

Elastic  force  of  vapour,  295 

Electric  light,  261 

Electricit3^  atmospheric,  301 

Ellison's  conical  brick  ventilators, 
224 

Embalming,  629 

Endemic  diseases,  412 

Energy  obtainable  from  food,  323 

Enteric  fever,  462 ;  from  jiolluted 
water,  13,  49,  65  ;  from  milk,  369; 
relation  of,  to  height  of  ground 
water,  266 

— carriers,  465 

Entozoa,  eggs  of,  in  water,  66 

Entozoic  diseases  on  sewage  farms, 
166 

Epidemic  diseases,  412,  699 

Epizootic  diseases,  525 

Equifex  disinfector,  606 

• — sprayer,  623 

Ergot,  384 

Erysipelas,  413 

Evaporation  of  rainfall,  3,  7,  21 ;  of 
water  on  sewage  farms,  165 

Excreniental  emanations,  181 

Excreta,  human,  76 

Exercise,  303 

Exit  shafts  for  foul  air,  227 

Ex})ectation  of  life  [sec  Wean  dura- 
tion of  life) 

Explosions  of  boilers,  256;  of 
lamps,  261 

Extraction,  ventilation  by,  228 

Extractives,  317 

Extracts  of  meat,  353 

Fabrics,  injury  to,  b}'  disinfection, 
602 

Factories,  ventilation  of,  232;  and 
workshops,  71 1 

Faeces,  composition  of,  76 

Fans,  extraction  by,  233;  propul- 
sion by,  235 

Fat  melting,  1 96 

Fats,  317 

Fatty  acids  of  butter,  ^jj 

Feeding  bottles,  330 

Fellmonger,  196 

Fermentation  of  organic  matters, 
II,  181  ;  vinous.  391  ;  acetous.  393 


INDEX 


731 


l'~uniu'ntcd  liquors,  392 

I'^evcrs,  sym])toms  of,  589 

Ficlclian  Rotary  Distributor,  1 54 

Filariasis,  522 

J""ilti'r  presses  for  sewage  sludge,  141 

Filters,  domestic,  60 

Filtration    of    water,     14,     52;    of 

sewage,  145,  160 
Fireplaces,  improvements  in,  244 
Fish,  352 
Fish  frying,  198 
Flame  illumination,  257 
Mashing  point  of  oils,  260 
Fleas,  509,  626 
I'Uies,  477,  469 
Flock,  "698 

Floor  space,  217;  in  hospital,  549 
tloors,  274;  hospital,  551 
Flour  {sec  Wheat) 
Flush  tanks,  86 
Flushing  gates  for  sewers,  126 
Fogs,  179,  297 
Food,  313;    proximate  constituents 

of,  313;  excess  and  deficiency  of, 

328;  unsound,  344,  686 
— standards,  404 
Foot  and  mouth  disease,  375,  537 
Foot-tons  of  potential  energy,  323; 

of  work,  305 
Formic  aldehyde,  614 
Foundations  of  houses,  269 
Friction,    loss    of    velocity    in    air 

shafts  by,  227 
Frosts,     as     obstacles    to     sewage 

irrigation,  165 
Fume  cremator,  75 
Fungi  in  water,  8;  in  milk,  359;  in 

liour  and  bread,  384 
Fur  in  boilers,  5,  256 
Furnace    chimneys,    connection    of 

sewers  with,  130 
Furnace  smoks,  2  r  i 
Furniture,  house,  205,  275 

Ganister  industry,  193 

Gas  {see  Coal  Gas) 

— cooldng  stoves,  343 

— fires,  245 

— governors,  259 

— pipes,   pressure  in,   259;   testing 

of,  180 
— works,  nuisance  from,  195 
Gelatine,  317 

Genn  theory  of  disease,  408 
Gemaicides,  598 
Gin,  392 
Glanders,  538 
Glossina  palpalis,  523 
—  morsitans,  523 
Glucose,  393 
Glue-making,  T97 
Gluten  of  Hour,  382 


(ioat's  cnilk,  35O,  519 

Goitre,  66 

(ioux  system  at  Halifax,  81 

Grates,  open,  243;  smokeless,  244; 
ventilating,  247 

Gravel  soils,  268 

Graveyards,  ])olUition  of  water  by, 
27;  pollution  of  air  by,  187; 
pollution  of  soil  by,  265,  628 

Grease  guUey,  1 12 

Greensands,  39 

Ground  air,  263 

— water  {sec  Underground  water) 

GuUey,  yard,  1 12 

Gunpowder  blasting,  19U;  substi- 
tutes for,  229 

Gut  scraping,  197 

Haemagglutinins,  422 
Ha^moglobinuria,  5 1 7 
H-,emolysins,  422 

Haffkine's  anti-cholera  vaccine,  417 
Haffkinc's  prophylactic,  513 
Hardness  of  water,  5 
Hawksley's  formula,  7 
Heat,  effects  of,  on  body,  278 
Heating  by  hot  water,  250 
— by  steam,  253 
Hendon  cow  disease,  369 
Hermite  system.  139 
Hinckes-Bird's   window   ventilator, 

222 
Hopper   closets,    89;    supply   from 

water  main,  48 
Hopper  inlet  ventilators,  223 
Horrocks  on  sewer  air,  182 
Horseflesh,  341,  688 
Hospitalfevers,  176,  548 
Hospitals,  548;  isolation,  553,  696; 

temporary' hut,  556;  pavilion,  554 
Hot-water  pipes,  250 
House,  construction  of,  273 
— drains,  104 
House-flies  {see  Fhes) 
Houses  of   ParUament,   ventilation 

of,  235 
Housing  and  Town  Planning  Act, 

706 
Housing  of  the  working  classes,  703 
Humidity,  relative,  254,  294 
Hydraulic  mean  depth,  123 
Hydrocarbons  {sec  Fats) 
Hydrophobia,  534 
Hygrometers,  292 
Hypochlorites,  53,  1^9,  612 

Immunity,  417 
Incubation  period,  409 
Industrial  poisonings,  199 
Infantile  mortality,  331,  657 
Infants,  feeding  of,  329 
— consultations,  331 


732 


HYGIENE  AND  PUBLIC  HEALTH 


Infection,  41  hS,  424 

Infectious  Diseases  (Notification) 
Act,  6gi ;  law  as  to,  692 

Influenza,  491 

Inlet  openings  into  rooms,  222 

Inoculations,  preventive,  417,  425 

Insects,  infection  from,  428 

Intemperance,  effects  of,  395 

Intercepting  sewers,  122 

Intoxication,  395 

Investigation  of  disease,  544 

Iron,  magnetic  carbide  of,  53; 
spongy,  52;  protosulphate  of,  as 
a  sewage  precipitant,  137 

Irrigation,  sewage,  161 

Island  climates,  281 

Isolation  of  infectious  diseases,  547 

Italian  rye  grass,  164 

Joints  of  drains,  104 
Joints,  soldered,  loi 

Kenwood    and    Butler    on    sewage 

treatment,  145 
Kerosene  oil,  260 
Kitson  light,  261 
Knackeries,  198 
Koch  on  water  filtration,  iS 
Koch's  postulates,  410 
Koumiss,  358 

Lactic  acid  bacilli,  360 

Lake  waters,  8 

Lamps,  260 

Latrines,  96 

Laundries,  716 

Lead,  solvent  action  of  water  on, 

43 
—pipes,  43 
— poisoning,  43,  199 
Leather  dressing,  196 
Lemon  and  lime  juice,  398 
Leprosy,  520 
Liemur's  system,  134 
Life  tables,  651 ;  old  and  new,  656; 

construction      of,      by      graphic 

method,  652 
Lime  as  a  sewage  precipitant,  136; 

chloride  of,  612 
— salts  in  water,  5 
Linen,  307 
Liquefaction   of   solids    in   sewage, 

143 

Liver  fluke,  338 

Local  Government  Board,  General 
Order,  1910,  Duties  of  M.O.H., 
724;  model  by-laws  for  privies, 
78  ;  for  cesspools,  79  ;  for  new 
streets  and  buildings,  209  ;  for 
offensive  trades,  195;  provision 
of  isolation  hospitals,  432 

Lodgings,  houses  let  in,  O85 


London,    water-supply    of,     i.     14; 

basin,    geological    formation    ot, 

29;  Building  Act,  210 
Louvre  ventilators,  222 
Lung  diseases,  from  overcrowding, 

1 76 ;  from  inhalation  of  dust,  1 92  ; 

from  dampness  of  soil,  266 

McCarrison,  Major,  on  goitre,  66 

Mackinnell's  ventilator,  226 

"  Made  "  soils,  268 

Magnesium  salts  in  water,  5,  38 

Malaria,  267,  513 

Mallein,  539 

Malta  fever,  5 1 9 

Manhole  chambers  on  house  drains, 
no 

Manholes,  sewer,  126 

Manure,  manufacture  of,  82  ;  earth- 
closet,  83;  sewage,  141 

Margarine,  377,  721 

Marriage  rate,  645 

Marsh  air,  187;  soils,  267 

Martin-Chick  test,  600 

Massachusetts  experiments,  17,  144 

Mean  age  at  death,  6 50 

Mean  duration  of  life,  654 

Means  of  series,  632 

Measles,  448 

Meat,  ^^2  ;  preservation  of,  344 

— condemned,  351 

— effects  of  diseased,  344 

— extracts,  353 

Mechanical  stokers,  212 

Medical  ofiicers  of  health,  668  ; 
duties  of,  724 

Mercurial  poisoning,  202 

Mercury,  bichloride  of,  as  a  disin- 
fectant, 609 

Metallic  poisoning  by  water,  67 

Metchnikoff's  theory,  418 

Metropolitan  sewage  discharge, 
Royal  Commission  on,  132 

Metropolitan  water  supply,  Royal 
Commission  on,  13 

Micro-organisms  [see  Organisms) 

Middens,  78 

Midwives  Act,  703 

Milk  and  Cream  Regulations,  720 

Milk,  355,  719 

— condensed,  361 

— depots,  376 

— dried,  ^76 

— epidemics,  368 

— sterilization  of,  360,  365 

Mineral  salts  in  food,  320 

— -waters,  390 

Miners,  lung  diseases  of,  188 

— nystagmus,  190 

Minas,  ventilation  of,  228 

— disposal  of  excreta  in,  120 

Montgolfier's  fonnula,  220 


INDEX 


733 


Mortality,  occupational,  i8o,  66 1 

-Mortuaries,  697 

Most[ui1()es,  267,  514,  519,  523 

Mountain  cliniatcs,  278 

Mumps,  454 

Musca  domcstica  {see  Flies) 

Mustard,  398 

Nitrates  and  nitrites,  in  well  waters, 
68;  from  oxidation  of  sewage,  1 58 
Nitrifying  organisms,  143,  160 
Nitrogen,  in  fasces  and   urine,   76; 
in   crops  of  sewage  farms,    165; 
in  diets,  323,  326 
Nitrous  acid  as  an  air  purifier,  620 
Notification  of  infectious  iliseases, 
691  ;  of   birtlis,   699;  of  measles, 
449;  of  tuberculosis,  488,  722 
Nuisances,     675;     from     oflensive 
trades,    195,    685;    from    smoke, 
213,  678;  law  as  to,  675,  676 

Oatmeal,  386 

Ocean  climates,  281 

Offensive  trades,  195,  685 

Ogle's,  Dr.,  comparative  mortality 

statistics,   188 
Oidinin  albicans,  368 
Old  age.  clothing  in,  310 
Ophthalmia,  contagious,  494 
Opsonins,  419 
Ordnance  map,  9 
— datum,  10 
Organic   matters   in   water,    69;   in 

air,  171 
Organisms,  aerobic,  143;  anaerobic, 

143;  in  air,  173 
Osier  beds  on  sewage  farms,  165 
Outlets  for  vitiated  air,  226 
Outworkers,  715 
Overflow  pipes,  from  cisterns,  46; 

from  cesspools,  88 
Oxidation  of  sewage  in  rivers,   1 1 ; 

of  sewage  in  the  soil,  160 
Oxychlo ride  process,  139 
Oxygen  in  air,  167,  171 
Oysters,  156,  468 
Ozone,  168 
Ozonization  of  air,  237;  of  water,  54 

Pail  system,  80 

Panel  system  of  heating,  253 

Paper  making,  199 

Paratyphoid  fever,  466 

Parry  Laws  and  Andrewes,  182 

Pasteur-Cham berland  filter,  6z 

Pasteur  treatment,  536 

Paving,  272 

Peas,  387 

Peat  acids,  44 

Pellagra,  386 

Peip^er,  398 


Percolation  of  rain,  2,  20 

Perflation  by  wind,  207 

Petroleum  oils,  260 

Petrolite  lamp,  261 

Phagocytosis,  418 

Phenoloids,  61 1 

Phenols,  610 

Phos])horus  poisoning,  200 

Phthisis,  produced  by  foul  air,  175; 

by  dust,  188  ;  l)y  <lamp  soils,  266; 

climatic   treatment   of,    278    [see 

also  Tuberculosis) 
Pickles,  398 
Pig  keeping,  199 
Pipe  sewers,  125 
Piroplasmosis.  542 
Plague,  507,  666 
Plenum  ventilation,  z^iT, 
Pneumonia,  497 
Poisson's  rule,  631 
Pole's  formula,  7 
Poliomyelitis,  496 
Pollution  of  rivers,  1 1  ;  of  wells,  23 ; 

of  the  soil,  265 
Population,  estimation  of,  636;  law 

of,  636;  census  of,  637 
Port  Regulations,  665 
Port  Sanitary  Authorities,  664 
Porter-Clark's  process,  51 
Portland  cement,  104 
Potassium  pennanganate,  613 
Potatoes,  387 
Poudrette,  82 
Precipitants,  sewage,  136 
Precipitins,  421 
Pressure  filters,  51 
Preventive  inoculations,  417 
Probability,  theory  of,  635 
Probable  duration  of  life,  655 
Propulsion,  ventilation  by,  233 
Proteids,  313 
Pseudo-tuberculosis,  484 
Ptomaines,  315,  345 
Puerperal  fever,  497 
Pulsometers,  36 
Pumps,  34 

Purification  of  sewage,  134 
— of  water,  50 
Putrefaction,   in    river  waters,    11; 

of    sediment    in    sewers,    88;    of 

meat,  345 

Quarantine,  505,  665 

Rabies,  534 

Radiation,  warminj,  by,  243 

Radiators,  255,  252 

Rag-flock  Regulations,  698 

Rain,    evaporation   of,    2;   percola 

tion  of,  2,  21 
Rainfall,  2 
Rain  gauge,  296 


734 


HYGIENE   AND   PUBLIC   HEALTH 


Rainwater  pipes,  1 12 

Rainwater,  3 

Ram,  hydraulic,  36 

Rats,  509,  666 

Reek's  disinfector,  606 

Refuse,  72 

Regulator  valves,  93 

Relapsing  fever,  spiriUum  of,  415 

Relative  values  of  series,  631 

— humidity,  254,  294 

Reservoirs,  water,  7 

Respiratory    impurity,    permissible 

limits  of,  215 
Rest,  after  exercise,  305 
Revenue  Act,  the,  1903,  710 
Rheumatic  fever,  500 
Rice,  387 

Rideal-Walker  test,  599 
Ridge  and  furrow  system,  163 
Rivers,    10;  pollution  of,    11,   682; 

self-purification  of,  1 1 
Road  paving,  272 
Roberts'  rain-water  separator,  5 
Roofing,  275 
Rotheln,  452 
Rye,  386 

Sago,  387 

Sanatoria  for  phthisis,  486 

Sanatorium  Benefit  under  the 
National  Insurance  Act,  489 

Sand  filtration,  15,  16,  17 

Sanitary  authorities,  663 ;  inspec- 
tors, 668 

— law,  663 

Scarlet  fever,  444 ;  from  milk,  369 

Scavenging,  72,  679 

Schizomycetes,  408 

Scholars,  hygiene  of,  566 

School  children,  566;  nervous  sys- 
tem of,  567;  vision  ot,  570;  hear- 
ing of,  573;  exercise  of,  574; 
postures  of,  576;  respiration  of, 
577;  circulation  of,  578;  skins 
of,  579;  clothing  of,  581;  food 
of,  582;  measurements  of,  583; 
infectious  fevers  of,  586;  ex- 
clusion of,  587 

School  cleaning,  566 

School  cloakrooms,  563 

School  desks  and  books,  563,  570 

School  drinking  cups,  565 

School  hygiene,  558 

School  mecJical  inspections,  590; 
schedule  of,  595 

School  w.c.'s  and  lavatories,  564 

Schools,  ventilation  of,  561;  light- 
ing of,  559;  wamiing  of,  561  ; 
closure  of,  586;  infection  in,  586; 
inspection  of,  592 

Scott-Moncricff's  system,  144 

Scurvy,  319;  infantile,  361,  362 


Sea,  discharge  of  sewage  into,  133 

— salts  in  tidal  waters,  i  ^^ 

Seasonal  prevalence  of  disease,  433 

Sedimentation,  14 

Septic  tank  system,  142 

Serum  diagnosis,  422,  428,  471 

Sewage  of  midden  and  water-closet 
towns,  ^y;  average  composition 
of,  134;  sludge,  141;  effluents, 
157;  farms,   i6i;  purilication  of, 

134 

Sewage  disposal,  131;  law  as  to, 
671 ;  Royal  Commission  on,  156 

Sewerage,  combined  system  of,  122; 
separate  system  of,  125 

Sewer  air,  181 ;  poisoning  from,  183  ; 
cremation  of,  130 

— deposits,  88 

— gases,  183 

— men,  health  of,  185 

— ventilators,  129 

Sewers,  121;  gradients  of,  123; 
velocity  of  flow  in,  123;  capacity 
of,  123;  shape  of,  124;  construc- 
tion of,  124;  flushing  of,  126; 
ventilation  of,  127;  movements 
of  air  in,  127;  outfall,  131;  law 
as  to, 670 

Shell-fish  in  tidal  waters,  1 56,  468 

Sheringham's  valve,  223 

Shone's  pneumatic  sewage  ejectors, 

133 
Short -sight  in  children,  570 
Silica  in  water,  44 
Silk,  309 

Simple  continued  fever,  455 
Siphonage,  86,  103 
Siphon  flush  tank  (Field's),  86 
— gulley,  112 

— traps,  90,  95;  disconnecting,  108 
Siphonic  closets,  91 
Sites  of  houses,  267 
Skin,  care  of  the,  309,  579 
Slate  beds  for  sewage  treatment,  148 
Slaughter  houses,  351,  688 
Sleeping  sickness,  523 
Slop  closets,  98 
Slop  sinks,  99 

— waters,  jy;  disposal  of,  84 
Small-pox,  416,  429;  hospitals,  432 
Smoke  nuisances,  678 
Smoke,  prevention  of,  211 
Soap,  309 
Soap-boiling,  196 
Sodium  hypochlorite,  612 
Softening  of  water,  5  1 
Softness  of  water,  5 
Soil  pipes,  100 
Soil  pipe  ventilator,  103 
Soils,  263;  for  filter  beds,   160;  for 

sewage  farms,  162  ;  favourable  to 

diarrhoea,  475 


INDEX 


735 


Specific  diseases,  41 1 

Spirits,  392,  722 

Spirochaite  cUscase,  501 

Spongy  iron,   for  purifying   water, 

52.61 
Spot  maps,  662 
Sprays,  disinfection  by,  621 
Springs,  20 
Stable  manure,  73 
Stables,  1 18 

Standard  deviation,  633 
Standards,  food,  404 
Starches,  318 
Statistical  fallacies,  639,  640,  645, 

660 
Statistics,  631 

Steam  blast  for  ventilation,  231 
— di.:.infection  by,  603 
—pipes,  253 

Steamships,  ventilation  of,  231 
Steining  of  wells,  26 
Sterilization  of  water,  53;  cf  milk, 

360,  365 
Stoddart's  distril)utor,  154 
Stokers,  mechancial,  212 
Storage  reservoirs,  7 
Stonn  overflows  to  sewers,  122 
Storm  waters,  150 
Stoves,  close,  248;  ventilating,  249 
Stream,  definition  of,  under  R.P.P. 

Act,  682 
Streets,  paving  of,  272 
Stuffy  atmospheres,  254 
Sub-irrigation,  85 

Subsoil,  drying  of  the,  265  ;  pollu- 
tion of ,  265  ;  drainage  of ,  125,265 
Sugars,  318,  393 
Sulphurous  acid  in  air,   179;  as  an 

air  purifier,  616 
Sunlight,  absence  of,  168 
Sunshine  recorder,  301 
Surface  waters,  2,^ ,  112 
Susceptibility  to  disease,  412 
Swimming    baths,    purification    of 

water  of,  57 
Sylvester's    system    of    ventilation, 

219 
Syphilis,  50 1 

Tabes  mesenterica,  m 

TcBnia  echinococciis ,  335,  339 

— mediocanellata,  339 

—solium,  333,  339 

Tank  sewer,  133 

Tanks,  sewage,    133;  precipitation, 

13s 
Tanneries,  196 

Taanin,  of  tea,  389;  of  wines,  392 
Tapioca,  387  ~ 

Tea,  389 

Testing  of  dra»  is  ana  soil-pipes,  I'lf 
Tetanus,  414 


Thermometers,  wet  and  dry  bulb, 
293;  maximum  and  minimum, 
298;  solar,  300;  terrestrial  radia- 
tion, 300 

Thresh's  disinfector,  607 

Thrush,  368 

Ticks,  543 

Tidal  rivers,  sewage  in,  132 

Tide  valve  for  sewers,  133 

Tin  miners,  191 

Tinned  foods,  399 

Tobacco,  403 

Tobin's  tube,  224 

Tonsillitis,  acute,  from  foul  <air,  184 

Town  planning,  706 

Toxins,  345,  423,  425 

Trade  effluents,  152 

Trade  nuisances,  194 

Traps,  efficiency  of,  115 

— water  seal  cf ,  95 

Trichina  spiralis,  335,  341 

Tripe  boiling,  196 

Tropical  climates,  276 

Trough  closet,  96 

Trypanosomes,  523 

Tsetse  fly,  524 

Tube  wells,  28 

Tubercle,  bacillus  of,  413;  in  cow's 
milk,  371 

Tubercular   peritonitis    from    milk, 

ill 
Tuberculin,  532 
Tuberculosis,    188,   413,   480,    531, 

722;  from  cow's  milk,  371;  from 

naeat,  347 
— Royal  Commission  on,  347,  483 
— Dispensary,  487 
— Order,  191 3,  722 
— Regulations,  191 2,  488 
— Sanatoria,  486 
Tumbling  bay  and  flap  valve,  1 3c 
Typhoid  fever  [see  Enteric  Fever) 
Typhus,  454 
Tyrotoxicon,  378 

Iltra  violet  rays  as  sterilizers,  55 
Underd rains  for  filter  beds,  160 
Underground  water,  20,  24;  curve 

of,  21,  24;  varying  level  of,  21, 

264 
Unhealthy  areas,  703 
— dwelhng  houses,  704 
— trades,  714 
Unsound  food,  686 
Upland  surface  waters,  6,  2i7 
Urea,  fermentation  of,  yj 
Urinals,  99 
Urinary  calculi,  65 
-^Jrine,  composition  of,  76 

Vaccination,  434-444 
— ^Acts,  702 


736 


HYGIENE    AND   PUBLIC    HEALTH 


Vaccine  Ijoiiph,  441 

Valve  closet,  92 

Vapour  in  air,  295 

Varicella,  453 

Variola  (see  Small-pox) 

Vegetable  acids,  319 

Vegetarianism,   316 

Vegetation,    effect   of,    on    climate, 

282 
Ventilation,      207;      of      inhabited 

rooms,  214 
Vinegar,  397 
\'ital  statistics,  636 

Wall  papers,  206 

Walls  of  houses,  269 

Warming,  243 

Washington  Lyon's  steam  disin- 
fector,  605 

Wash-down  closet,  89 

Wash-ont  closet,  90 

Wassermann  reaction,  422 

Waste-pipes,   1 1 1 

— water  meter  (Deacon's),  42 

— waters,  jj 

Waste -water  closets,  94 

Water,  i ;  sources,  collection,  and 
storage  of,  2;  quantity  required, 
40;  waste  of,  42,  49;  constant 
service  of,  48;  intermittent  ser- 
vice of,  45;  sterilization  of,  53; 
opinion  upon  purity  of,  68;  com- 
position of,  ^y;  purification  of, 
50;  temperature  of,  in  mains,  42 ; 
subsoil,  261 ;  as  food,  321  ;  law  as 
to.  680 

Water-bearing  strata,  29 

Water-carriage  system,  88 

Water-closets,  88;  flushing  of,  91; 
law  as  to,  673 

Water  gas,  246 

Water  mains,  42 

Water  pipes,  49 

W^ateqiroof  materials,  300 


Water  samples,  opinion  upon,  68 

Water  softening  processes,  51 

Water  vapour  in  air,  294 

Water-waste  preventers,  91 

Water-wheels,  36 

Weather  observations,  283 

Weight  of  the  air,  291 

Well  borings,  30 

Wells,  23;  shallow,  23;  deep,  28; 
artesian,  31;  tube,  28;  examina- 
tion of,  27 

Well  waters,  38 

Welsbach  incandescent  gas  burner, 
258 

Wheat  flour,  379;  bleaching  of,  381 

Whey  cream  mixture,  358 

Whisky,  392 

Wholemeal  flour,  379 

Whooping-cough,  452 

Widal's  test,  471 

Wind  pressure,  292 

Windows  as  ventilators,  222 

— in  schoolrooms,  560 

Winds,  as  ventilating  agents,  207, 
219;  effects  of,  on  body,  2yy 

Wines,  392 

Wool,  307 

Wool  sorting,  232 

Woolsorter's  disease  {see  Anthrax) 

Work,  average  day's,  306 

Working  classes,  housing  of  the,  703 

— lodging  houses,  706 

Woniis,  round,  340 

— thread,  340 

Yard,  paving,  271 

Yeast,    in    bread    making,    382 ;    in 

fermenting  liquors,  391 
Yellow  fever,  519 
Yersin's  plague  serum,  513 

Zinc  cisterns,  46 

Zymotic  diseases,  410;  death-rates 
from,  649 


H.    K.    LIWIS,    X36,    (iOWEK   STKF.KT,    LONDON 


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